Orbit student ahc umn edu by mikeholy


									                         Posterior Triangle and Suboccipital Region
Posterior Triangle and Suboccipital Region

Bony landmarks:

       Superior nuchal line of skull
       posterior tubercle of atlas (C1 vertebra)
       spinous process of axis (C2 vertebra)
Posterior Triangle

       1) Trapezius

 Function: extends head if scapula is fixed, raises the arm, elbow forward.
 Innervation: spinal accessory nerve (CN XI)

       2) Sternocleidomastoid

 Origins: medial 1/3 of clavicle and front of manubrium.
 Insertion: mastoid process.
 Function: turns and tilts the head, (and accessory muscle of inspiration).
 Innervation: spinal accessory nerve (CN XI)

       3) Middle Third of Clavicle
       4) Apex: Superior Nuchal line of skull

Muscles in the Posterior Triangle:

       Platysma: Most superficial muscle in the posterior triangle. Think of it as the "Roof" of the posterior
                     Muscles of facial expression
                     Helps depress jaw
                     Aids circulation by relieving pressure on veins
              Innervation: cervical branch of facial nerve.

Muscles forming the floor of the posterior triangle:

  Muscle             Origin                Insertion                    Function                Innervation
             Vertebral spinous
Splenius     processes of C3-T5      Superior nuchal                                        Upper cervical
                                                           extends and rotates head
capitis      (part of erector spinae line                                                   dorsal rami
                                                                                            Ventral ramus (C3-
Levaltor     Transverse processes                          Bends neck when scapula fixed;
                                      Medial scapula                                        C4) and dorsal
scapulae     (C1-C4)                                       elevates and rotates scapula.
                                                                                            scapular nerve.
                                                         Bends neck forward and to the
                                      Upper surface of side. When they both act
Middle       Transverse processes
                                      first rib (behind  together, they fix the neck or if   C4-C8
Scalene      C1-C7
                                      subclavian groove) the neck is fixed, they elevate the
Posterior    Transverse process of Lateral surface of
                                                           Same as middle scalene           C7-C8
Scalene      C5-C6                 second rib


Vasculature of Posterior Triangle:

External jugular vein

       Comes from a union of the posterior auricular and retromandibular veins and then crosses the
   sternocleidomastoid and drains into the subclavian vein. One can distinctly see it pulsate especially under
   high venous pressure.
Bear in mind that there is variability in where these arteries arise from.

       Transverse cervical artery: comes from the thyrocervical trunk OR as a separate trunk with the
   suprascapular artery and supplies the trapezius and levator scapulae. Note that the transverse cervical
   artery does not run with the transverse cervical nerve. The nerve proceeds anteriorly whereas the artery
   proceeds posteriorly.
     Third part of subclavian artery:The longest portion of the subclavian artery. Supplies blood to the
   Upper limb.
       Suprascapular artery: Comes from the thyrocervical trunk OR from a common trunk with the
   transverse cervical artery. Supplies Shoulder.
      Dorsal scapular artery: Comes directly from the subclavian artery (70%) OR the thyrocervical trunk
   (30%) and supplies the Medial shoulder.
Innvervation of Posterior Triangle

       Sensory: From Cervical Plexus
       Motor: Spinal accessory CN XI
Think of the locations of the nerves as if they were hands on a clock...

               Great auricular n. (12:00):supplies innervation to the skin over the parotid gland, the posterior
       aspect of auricle and an area of skin from mandible to mastoid process, runs superficial to
       sternocleidomastoid and in an anteriosuperior direction.
              Lesser occipital n. (1:00): Supplies the skin of neck and scalp posteriosuperior to auricle, and
       runs posterior to sternocleidomastoid.
               Accessory n. (4:00): Supplies SCM from deep aspect, then passes posterior-inferiorly to supply
       the trapezius.
               Supraclavicular n. (6:00): Supplies skin of upper anterior chest wall and adjacent shoulder.
               Transverse cervical n. (9:00): Supplies skin of anterior neck
Note: the clock analogy is of the left side. It would be backwards from the other side.

All of these nerves come out from behind the SCM. You can locate them by palpating along the SC< until you
reach a point that hurts when pressure is applied. You can think of GLAST (sounds like "blast") if that helps
you remember it...

Highlights From the Suboccipital Region:

The four muscles of this triangle serve to anchor the atlas and axis to each other and to the skull.

      Deep Muscles               Nerve Supply                                Function
Obliquus capitis inferior      Suboccipital nerve Ipsilaterally rotates C1 with respect to C2
Obliquus capitis superior      ""                   extends the head
rectus capitis posterior major ""                   extend the head backwards, act as fine-tuners, proprioceptors
rectus capitis posterior minor ""                   ""

You should know insertions and origins for all of the deep muscles, as these form the corners of the suboccipital

Other Important Information About the Suboccipital Triangle

In addition to the contents of the suboccipital triangle, know these too:

       1) Vertebral artery - compression of this artery due to prolonged rotation can cause dizziness.
       2) Suboccipital nerve (dorsal rami of C1)
       3) Greater Occipital nerve: Closely associated with this triangle. It emerges below the inferior border
   (obliquus capitis inferior) and runs superficially to this space to innervate the posterior scalp.
                      Anterior Triangles of Neck and Cervical Viscera

The Anterior triangle (Netter 24)


       Anterior midline of neck
       Inferior edge of mandible

       Omohyoid m.
       Digastric m.
       Hyoid bone

Sub-Triangles of the Anterior Triangle

                           Submandibular Triangle:

                                    mandible (sup.)
                                    digastric (ant.-inf.and post.-inf.)
submandibular ∆

                           Submental Triangle(unpaired)

                                    Anterior bellies of digastric (lateral)
                                    mandible (anterior)
Submental ∆
                           Muscular Triangle

                                  sterocleidomastoid (posterior)
                                  superior belly of omohyoid (posterior - superior)
                                  midline; hyoid bone (superior)
Muscular ∆

                           Carotid Triangle

                                  posterior belly of digastric (anterior - superior)
                                  sternocleidomastoid (posterior)
                                  sup. Belly of omohyoid (anterior - inferior)
Carotid ∆

Hyoid Bone

Hyoid bone (Moore T-8.3)

Characteristics: U-shaped Portions:

       Greater horn
       Lesser horn

       Raises/lowers larynx
       Provides stable platform for the:
              suprahyoid m.’s (primary depressors of mandible)

Superior Attachments                   Inferior Attachments              Other Attachments
Suprahyoid Muscles                     Infrahyoid Muscles                Middle Pharyngeal Constrictor
Other m's of mouth & tongue            Thyrohyoid Membrane
Suprahyoid Muscles

Suprahyoid Muscles (Netter 25)

Digastric Muscles Stylohyoid Mylohyoid Geniohyoid: deeper Table 8.3 in Moore is good reference. However
geniohyoid muscle is mislabeled.

All suprahyoid muscles elevate the larynx and inferior pharynx and all elevate the floor of mouth to propel
contents of mouth into pharynx. All can stabilize hyoid during speech and swallowing.
SUPRAHYOID                                           Stylohyoid                               Geniohyoid
                     Digastric Muscle                                  Mylohyoid Muscle
MUSCLES                                              Muscle                                   Muscle
                     2 bellies:

                            posterior belly:
                         mastoid notch of            styloid process of mylohyoid line of     inferior mental
Origin                   temporal bone               temporal bone      mandible              spine of mandible
                             anterior belly:
                         digastric fossa of
                         posterior mandible
                                                                       onto body of hyoid,
                     intermediate tendon to hyoid body of hyoid
Insertion                                                              and onto itself on     body of hyoid
                     bone                         bone
                     depresses mandible and          elevates &        elevates and protracts
Function                                                                                      protracts hyoid
                     elevates hyoid                  retracts hyoid    hyoid
                     2 bellies:

                            posterior belly: facial cervical branch
Innervation              nerve                                         mylohyoid n. (V3)      C1
                                                    of Facial n.
                             anterior belly: nerve
                         to the mylohyoid (V3)
Muscular Triangle and Infrahyoid Muscles

(Netter 25A, 25B; Moore 8.12)

                                       General observations on the infrahyoid muscles:
                                       Made for mobility of larynx and pharynx

                                       Actions depend on actions of the suprahyoid muscles

                                       Help co-ordinate movements of the head, neck, tongue, larynx and
                                       pharynx They are flexors of the neck in conjunction with the suprahyoid

                                       Contraction of the infrahyoid and suprahyoid muscles simultaneously:

                                              with jaw fixed → fixes hyoid bone, provides firm base for
                                           tongue movement (speech)
                                               with jaw mobile → depresses the jaw (with suprahyoids and
Muscle      Sternohyoid              Sternothyroid                    Thyrohyoid            Omohyoid
                                                                                            superior scapula
            manubrium and medial posterior surface of                                       (just medial to
Origin                                                                thyroid cartilage
            clavicle             manubrium                                                  suprascapular
                                                                      body and greater horn
Insertion   body of hyoid            thyroid cartilage                                      hyoid bone
                                                                      of hyoid
                                                                      depresses hyoid OR
            depresses hyoid, e.g.,   depresses hyoid (indirectly)
                                                                      elevates larynx.      depresses & retracts
            after elevation during   depresses thyroid cartilage
                                                                      Opposes larynx to     hyoid draws hyoid
Function    swallowing stabilizes    (directly) depresses thyroid
                                                                      epiglottis, i.e.,     laterally when
            hyoid, e.g., during      cartilage, i.e., lengthens the
                                                                      shortens the vocal    turning head
            opening of mouth         vocal cords
                                                                      C1, branch from fibers
Innervation C1, C2, and C3           C2 and C3                        running with the       C1, C2, and C3.
                                                                      hypoglossal nerve
Position    superficial              deep to sternohyoid              deep to sternohyoid
Ansa Cervicalis: innervation of infrahyoid muscles (Netter 27, 28A,
Comprised of branches of C1, C2, and C3

Superior root: runs with hypoglossal n.

Inferior root: direct branch of cervical plexus

Not a true loop: no recurring fibers: two descending branches join,
forming a "Y". Supplies infrahyoid muscles more superior roots supply
more superior muscles (and vice versa)

does not supply the thyrohyoid)
Carotid Triangle

(Netter 24)

Separated from the muscular triangle by the superior belly of the omohyoid muscle

Bounded by:

       Posterior belly of digastric
       Superior belly of omohyoid
Contents of carotid triangle: (Netter 27, 28A, 28B)

       Within Carotid sheath
common carotid artery, internal jugular vein, vagus nerve, retromandibular vein, facial vein, superior and
middle thyroid veins, ansa cervicalis; superior root (sometimes)

       Outside Carotid Sheath: (Netter 28A, 28B)
hypoglossal nerve, spinal accessory nerve, ansa cervicalis, branches of vagus nerve: internal and external
branches of superior laryngeal nerve, recurrent laryngeal n., branches of external carotid a.
Branches of the common carotid artery
(Netter 30A, 30B)

       Internal carotid artery
no branches in the neck; supplies structures in skull

       External carotid artery
8 branches; supplies structures external to skull

Branches of External Carotid Artery:
(Netter 30A, 30B)

                                                    Superior thyroid artery: to the thyroid gland gives off superior
                                                    laryngeal artery runs through thyrohyoid membrane runs with
                                                    internal laryngeal nerve

                                                    Ascending pharyngeal artery: small & deep to posteriolateral

                                                    Lingual artery: runs behind posterior belly of the
                                                    digastricsupplies the tongue

                                                    Facial artery: supplies face may be a common linguofacial
                                                    trunk pulse palpable crossing mandible

                                                    Occipital artery:supplies posterior scalp + SCM runs
                                                    posteriorly along post. belly of digastric,to sternocleidomastoid

                                                    Posterior Auricular artery: branch level: superior border of
                                                    posterior belly of digastric supplies the parotid gland, ear, scalp
                                                    and structures in temporal bone

                                                    Maxillary artery:supplies maxillary region

                                                    Superficial temporal artery: supplies temporalis muscle, etc

                                                    Transverse facial artery
Other contents of the carotid sheath

(Moore 8.14)

       Carotid body
               location: bifurcation of common carotid a.
               innervation: glossopharyngeal nerve
               responds to increasing pCO2 or decreasing p02

       Carotid sinus
               dilation of proximal internal carotid artery
               innervation: glossopharyngeal nerve
               responds to decreasing blood pressure

Root of the Neck: Junction of the Neck and Thorax

(Netter 29A, 29B; G.D fig 7.62)

Boundaries (Includes superior thoracic aperture)

       Lateral: first rib
       Posterior: T1 vertebral body
       Anterior: manubrium
Contents: Arteries, veins, lymphatics , nerves, muscles

Arteries of Root of Neck (Netter 29A, 29B; Moore fig 8.19)

       Right - brachiocephalic trunk, right subclavian artery, right common carotid artery, thyroid ima (?)
   artery (found in 4-10% of population, runs in anterior midline, interferes with tracheotomy
       Left-left subclavian, left common carotid

Branches of Subclavian Artery

(Netter 29A, 29B)

                               Subclavian artery: 3 parts: medial, posterior, or lateral to the anterior scalene
                               (Observe brachiocephalic vein branching into subclavian and jugular)\

                               Thyrocervical trunk
                               branches posteriorly to:

                                       inferior thyroid artery
                                       ascending cervical artery
                               variable branches:

                                       transverse cervical a.
                                       suprascapular a.
                                       dorsal scapular a.
                        Vertebral artery

                              ascends through transverse foramena starting with C6 enters skull via
                           foramen magnum characteristic relationship with longus colli and anterior
                        Internal thoracic (mammary) artery

                              branches anteriorly & inferiorly
                        Costocervical trunk

                              branches posteriorly from 1st part on the left
                              branches from 2nd part on the right
                                      1)superior intercostal artery
                                      2)deep cervical artery

Veins of Root of Neck

(Moore 8.8)

                                   Brachiocephalic vein

                                           Internal jugular vein in carotid sheath
                                           Subclavian vein continues as axillary vein
                                           External jugular vein drains face and scalp
                                           Anterior jugular vein may only be 1
                                   Both brachiocephalic veins drain into the superior vena cava
Muscles of the Anterior Neck

(Netter 25) (the obligatory chart)

MUSCLE                INNERVATION                            FUNCTION
Cervical Muscles
                                                             Depresses lower jaw, lip, and angle of the mouth,
Platysma              VII (cervical branch)
                                                             wrinkles skin of neck.
                                                             Singly, turns face toward opposite side.
Sternocleidomastoid XI
                                                             Together, flexes head, raises thorax.

Suprahyoid Muscles
                      2 Bellies:

                              Posterior Belly- VII           Elevates hyoid and floor of mouth, depresses
                              Anterior Belly- Nerve to the
                           mylohyoid (V3)
Mylohyoid             Mylohyoid n. (V3)                      Elevates and protracts hyoid.
Stylohyoid            VII (cervical branch)                  Elevates and retracts hyoid.
Geniohyoid            C1                                     Protracts hyoid.
Infrahyoid Muscles (Strap Muscles)
Sternohyoid           C1, C2, C3 (Ansa cervicalis)           Depresses and stabilizes hyoid.
                                                             3 functions:

Sternothyroid         C2 and C3 (Ansa cervicalis)                   Depresses hyoid (indirectly).
                                                                    Depresses thyroid cartilage (directly).
                                                                    Lengthens vocal cords.
                                                             Depresses hyoid OR elevates larynx.
                      C1 (which runs with the hypoglossal
                      nerve)                                 Shortens vocal cords.

                                                             Depresses and retracts the hyoid.
Omohyoid              C1, C2, C3 (Ansa cervicalis)
                                                             Draws hyoid laterally when turning the head

Important Points:

       Suprahyoid muscles elevate the hyoid bone, infrahyoid muscles depress the hyoid bone.
      The dual innervation of the digastric muscle (due to the embryological origin of the anterior and
   posterior bellies from the 1st and 2nd pharyngeal arches, respectively).
       Landmark: the digastric muscle almost always passes through the middle of the stylohyoid muscle
                                  Face, Scalp, and Parotid Region
Trigeminal Nerve (Cranial Nerve 5)

Has 3 branches

                                                                                 Special                  Cranial
CN#      Name              Sensory                         Motor                         Parasymp.
                                                                                 Sensory                   Exit
                 Cornea, skin of forehead                                                              Superior
V1    Ophthalmic & ant. scalp, eyelids,                                                                orbital
                 nose                                                                                  fissure
                   Skin over maxilla
V2    Maxillary    (includes upper lip),
                   maxillary teeth
                 Skin over mandible, incl.    Muscles of mastication,
                 lower lip mandibular         mylohyoid, ant. belly of                                 Foramen
V3    Mandibular
                 teeth, anterior 2/3 of       digastric, tensor veli palatini,                         ovale
                 tongue                       tensor tympani

Facial Nerve (Cranial Nerve 7)

                                           It emerges from the skull through the stylomastoid foramen and gives
                                           off its posterior auricular branch, which ascends behind the auricle
                                           to supply the auricularis posterior and occipitalis muscles. Here, it also
                                           gives off branches to the posterior belly of the digastric and
                                           stylohyoid, and receives postganglionic parasympathetic secretomotor
                                           fibers for the parotid gland from the otic ganglion via the
                                           auriculotemporal nerve (parasym. hitchhike on this nerve). Gee, that
                                           was a mouthful. It then enters the parotid gland, supplying it with
                                           postganglionic parasympathetic secretomotor fibers as it forms a
                                           plexus within its substance. The temporal, zygomatic, buccal,
                                           marginal mandibular, and cervical branches emerge along the
                                           borders of the parotid gland and innervate the facial muscles.

High Yield

        CN VII is motor to ALL muscles of facial expression
        To be redundant (it helps), CN VII emerges from Stylomastoid Foramen and runs through Parotid
     Gland. Thus, post surgical complications involving the parotid gland may include facial paralysis.
       Branches: ―To Zanzabar By Motor Car, Please‖
               Marginal Mandibular
               Posterior Auricular
      Don’t confuse the buccal branch of CN VII with the buccal n. off of V3 (sensory to buccal mucosa of
       With the use of a permanent marker, you can roughly draw the branches on your friends’ faces as shown

Muscles of Facial Expression

       Lower yield
       These muscles are all innervated by the 7th cranial nerve (facial).
       They all insert into the skin and are derived from the 2nd branchial arch.
       buccinator m.- One of my favorites. Without this m. we would be constantly biting our cheek while

      Muscle               Origin             Insertion         Main Action           Nerve           Notes
Frontal belly of
occipitofrontalis    Epicranial           Skin of forehead Raise eyebrows,                      No bony
                                                                                    branch of
(frontalis) -        aponeurosis          and eyebrows     wrinkle forehead                     attachments
                                                                                    facial n
                     Median plane of                        Oral sphincter –
                     maxilla (superiorly) Mucous            whistling &                         1st sphincter of
Orbicularis oris     and mandible         membrane of       sucking – speech,                   the GI, fibers are
                     (inferiorly), deep   lips              chewing (holding                    in lips
                     skin                                   food against teeth)
Dilator mm:
zygomaticus major,                                          Used to open mouth
levator labii                                               very wide, in
                   Lips                   Various
superioris alaque                                           mimicry (actors,
nasi, buccinator,                                           mimics)
depressor labii
depressor anguli
oris, buccinator,
                                                                                              Divides into 2
                    Frontal process of
Levator labii                            Skin of upper lip Raise lip, flair                   attaching to the
superioris alaque                        and alar          nostril, raise angle               cartilage of nose
nasi                                     cartilage of nose of mouth                           & upper lip to
                                                                                              elevate them
                                                           Elevates and
                    Incisive fossa of    Skin at the angle
Mentalis                                                   protrudes lower lip
                    mandible             of the mouth
                                                           – doubt
                    Mandible,                              Presses cheek
                    pterygomandibular                      against molars for                 Smiling, chewing
Buccinator          raphe, alveolar      Angle of mouth    chewing/ blowing/                  (holds cheeks
                    processes of maxilla                   whistling/ sucking                 against molars
                    and mandible                           facial expression
Depressor anguli                                           Frowns (helped by
                                         Angle of mouth
oris                                                       posterior platysma)
                                                           Raise corners of
Levator anguli oris Infraorbital margin Angle of mouth
Zygomaticus major Zygomatic bone         Angle of mouth Smiling/laughing
Zygomaticus minor Zygomatic bone         Obicularis oris   Contempt/sadness
                                                           Raise and evert
                                                           upper lip, deepen
Levator labii
                    Infraorbital margin Upper lip          nasolabial sulcus
                                                           w/Z. minor -
                                                           Pulls lip              branch of
Depressor labii                                                                               Lateral to
                    Mandible             Obicularis oris   inferolaterally –      facial n
inferioris                                                                                    mentalis
                                                           impatience             (inferior
                                        Fascia over                            Marginal
                    Platysma, fascia of                   Pull mouth laterally
Risorius                                parotid, angle of                      branch of
                    masseter                              – grinning
                                        mouth                                  facial n
                                                           Inferior attachment:
                                         Mandible, skin    depresses mandible
                    Superficial fascia                                          Cervical
                                         of cheek, angle   (grimace), superior
Platysma            off deltoid and                                             branch of
                                         of mouth,         attachment: tenses
                    pectoral region                                             facial n
                                         obicularis oris   skin of lower face
                                                           and neck
                                                                               Zygomatic      Fibers sweep
                                                         Wrinkles forehead, branch of         concentrically
                    Medial orbital
                                        Skin around      closes eyelids:       facial n       around eyelid, 3
                    margin, medial
Orbicularis oculi                       margin of orbit, palpebral does        (inferior      parts: lacrimal
                    palpebral ligament,
                                        tarsal plate     lightly, orbital does part);         (drains lacrimal
                    and lacrimal bone
                                                         tightly               Temporal       fluid – part
                                                                               branch of      of/deep to
                                                                                   facial n      palpebral),
                                                                                   (superior     palpebral (closer
                                                                                   part)         to orbital
                                                                                                 fissure), orbital
                    Orbital part of
supercilii - You’ve                                           Wrinkles medial
                    obicularis oculi,       Skin of eyebrow
got to love the                                               forehead - concern
                    nasal prominence
                                                              Makes transverse     Buccal
                      Continuous with       Bridge of nose
Procerus                                                      wrinkles across      branch of
                      frontalis             (contralaterally)
                                                              nose                 facial n
                                                              Widens nostril       Buccal
                      Maxilla superior to Mobile part of
Depressor septi                                               during deep          branch of
                      incisor             nasal septum
                                                              breathing            facial n
                                                             Draws ala (side) of                 Main muscle of
                      *Superior part of
                                            Nasal cartilage: nose towards the    Buccal          the nose
                      canine ridge of
Nasalis                                     *dorsum **alar septum: *closes       branch of       *Compressor
                      maxilla **Above
                                            cartilage        nostril **flares    facial n        naris **Dilator
                      compressor naris
                                                             nostril                             naris

Glossopharyngeal Nerve (Cranial Nerve 9)

          Parasympathetic Innervation to the Parotid Gland
      Pathway: glossopharyngeal n. (preganglionic fibers) tympanic branch            lesser petrosal n.   otic
   ganglion auriculotemporal n. (V3) (postganglionic fibers) parotid gland

Blood Supply

external         facial a - mm facial    superior and inferior labial a - upper lip,        angular a - superior
carotid        expression              nose side & septum, lower lip and chin (inf)       cheek, lower eyelid
                 superficial temporal - transverse temporal - parotid, facial mm,
               facial mm, skin         skin
                 inferior alveolar       mental - facial mm of chin
internal                                     supraorbital and supratrochlear - forehead
                 opthalmic a
carotid                                   / scalp skin, facial mm

Some extra facts mentioned in your lectures this year:
1. A baby's cranium is disproportionately large when compared to the face. This changes with the development
of the maxilla, mandible, paranasal sinuses, and the eruption of the teeth.
2. As we age, we wrinkle in lines that are perpendicular to the facial mm that are deep to the area. So, be sure to
suture in the wrinkle line!
3. Superficial Scalp wounds do not bleed as much as deep scalp wounds. This is because in a deep scalp wound
the apeuronosis is cut. Further, the frontal and occiptal bellies of the occipitofrontalis mm. pull the wound open
and this allows for heavy bleeding. Be sure to suture deep scalp wounds.
4. Black eyes (Ecchymosis) can arise from injury to the scalp or the forehead. This is because the frontalis
inserts on the skin. The blood can't go towards he neck because that area is protectd by the occipital belly of the
occipital frontalis mm.
5. Emissary Viens" have the potential to spread infection.
6. To Zanzabar By Motor Car. The first letter of each word stands for the 5 branches of the facial nerve:
temporal, zygomatic, buccal, marginal mandibular, and cervical.
7.Blepherospasm- the forceful involuntary contraction of mm around the eye.
8. Hemifacial spasm- the forceful contraction of the facial mm. ipsilaterally.
9. Scalp lacerations- remember that when you see a scalp laceration that all of the vasculature to that area is
ciming up (from the face). If you flap the scalp superiorly then you are removing it from its innervation and
blood supply (don't do this). Instead, flap the skin inferioly.
10. When you speak you are squishing the partoid gland between the ramus of the mandible and the mastoid
processes. Thus, an infection here is painful.
11. The lymphatics of the face, scalp and parotid region all eventually drain into the deep cervical nodes along
the internal jugular vien.
                    Infratemporal Region and Muscles of Mastication
Learning Objective #1

Review bony anatomy of the temporal fossa:

The Temporal Fossa (N4, N12, check out your skull)

      It is bounded superiorly and posteriorly by the temporal lines and anteriorly by the frontal and
   zygomatic bones.
       The temporal fascia stretches over the temporal fossa and the temporalis muscle.
       Inferiorly, the temporalis fascia splits into two layers, superficial and deep.
       The superficial layer is attached to the superior margin of the zygomatic arch.
      The deep layer passes medial to the arch to become continuous with the fascia deep to the masseter
       The floor of the temporal fossa which gives origin to the temporalis muscle, is formed by portions of
   the four bones: parietal, frontal, greater wing of sphenoid, and squamous part of the temporal bone.
       The area where the bones meet is called the pterion.
Clinical Correlation: This is an important landmark because the bone is exceptionally weak and is superior to
the middle meningeal artery and cause an epidural hematoma.

      The temporal fossa contains the fan-shaped temporalis muscle, the "handle" of which passes deep to the
   zygomatic arch.
       The temporal fossa is deepest where the temporalis muscle is thickest (anteroinferiorly).

Learning Objective #2

To be able to define the boundaries and contents of the infratemporal fossa, with special emphasis on the bony
foramina that allow entrance and exit into this region.

The Infratemporal Fossa (N4, N12, your skull)

     This is an irregularly shaped space inferior and deep to the zygomatic arch and posterior to the
      It communicates with the temporal fossa through the interval between the zygomatic arch and the skull,
   which is traversed by the temporalis muscle and the deep temporal nerves and vessels.

Bones and Walls of the Infratemporal Fossa (N4, N12, your skull)

       Lateral wall: ramus of the mandible.
       Medial wall: lateral pterygoid plate of the sphenoid bone.
      Anterior wall: infratemporal surface of the maxilla. This wall is limited superiorly by the inferior
   orbital fissure and medially by the pterygomaxillary fissure.
       Posterior wall: the condylar process of the mandible and the styloid process of the temporal bone.
      Roof (superior): this is formed by the flat inferior surface of the greater wing of the sphenoid bone. It is
   separated from the temporal fossa by a ragged edge called the infratemporal crest.
     The foramen ovale (through which V3 travels) and spinosum (through which the middle
   meningeal artery passes) open into the roof of the infratemporal fossa.
      Inferior boundary: the point where the medial pterygoid muscle attaches to the medial aspect of the
   mandible near the angle.

First word of warning: you will want to know what comes out of each of the small foramen in the base of the
skull for the test; this should be highlighted in the cranial nerves lecture.

Contents of the Infratemporal Fossa

       This fossa contains the inferior part of the temporalis muscle, the medial and lateral pterygoid muscles,
   the maxillary artery, the mandibular and chorda tympani nerves, the otic ganglion, and the inferior alveolar,
   lingual and buccal nerves.

The Maxillary Artery (N36, 30)

       This vessel is the larger of the two terminal branches of the external carotid artery.
      It arises posterior to the neck of the condylar process of the mandible and passes anteriorly, deep to the
   neck, and traverses the infratemporal fossa.
       It passes superficial to the lateral pterygoid muscle and then disappears in the infratemporal fossa.
       The middle meningeal artery, the largest of the meningeal artery, a branch of the maxillary artery,
   ascends between the two roots of the auriculotemporal nerve and enters the skull through the foramen
   spinosum to supply the dura and the interior of the cranium.

The Mandibular Nerve (V3) (N42)

       All nerves in the infratemporal region (auriculotemporal, inferior alveolar, lingual and buccal nerves)
   are branches of the mandibular nerve, except for the chorda tympani which is a branch of the facial nerve
       The mandibular nerve descends from the middle cranial fossa through the foramen ovale into the
   infratemporal fossa.
       The anterior division includes the masseteric n., several deep temporal n., medial and lateral
   pterygoid nn., and the buccal n.
      The posterior division includes the ariculotemporal n., inferior alveolar n., and the lingual n. More to
   come below!

The Otic Ganglion (N128, N125)

       This parasympathetic ganglion is located in the infratemporal fossa, just inferior to the foramen ovale.
       It is medial to the mandibular nerve, and posterior to the medial pterygoid muscle.
       Preganglionic parasympathetic fibers are mainly derived from the glossopharyngeal nerve (CN IX).
      The postganglionic fibers, which are secretory to the parotid gland, pass from this ganglion to the
   auriculotemporal nerve.

Learning Objective #3

Understand the function and innervations of the muscles of mastication.

Muscles of Mastication that act on the Temporomandibular Joint (Learning Objectives 4 and 5 will
further elucidate on the TMJ)

       Movements of the temporomandibular joint are chiefly from the action of the muscles of mastication.
       The temporalis, masseter, and medial pterygoid muscles produce biting movements.
      The lateral pterygoid muscles protrude the mandible with the help from the medial pterygoid muscles
   and retruded largely by the posterior fibers of the temporalis muscle.
      Gravity is sufficient to depress the mandible, but if there is resistance, the lateral pterygoid,
   suprahyoid and infrahyoid, mylohyoid and anterior digastric muscles are activated.
                 Actions                                                    Muscles
Depression (Open mouth)                      Lateral pterygoid, Suprahyoid, and Infrahyoid
Elevation (Close mouth)                      Temporalis, Masseter, and Medial pterygoid
                                             Masseter (superficial fibers), Lateral pterygoid, and Medial
Protrusion (Protrude chin)
Retrusion (Retrude chin)                     Temporalis and Masseter (deep fibers)
Side-to-side movements (grinding and         Temporalis on same side, Pterygoid muscles of opposite side, and
chewing)                                     Masseter

The Temporalis Muscle (N42, N50, N143)

       This is an extensive fan-shaped muscle that covers the temporal region.
       It is a powerful masticatory muscle that can easily be seen and felt during closure of the mandible.
       Origin: floor of temporal fossa and deep surface of temporal fascia.
      Insertion: tip and medial surface of coronoid process and anterior border of ramus of mandible.
      Innervation: deep temporal branches of mandibular nerve (CN V3).
       The temporalis elevates the mandible, closing the jaws; and its posterior fibers retrude the mandible after
The Masseter Muscle (N50, N51)

      This is a quadrangular muscle that covers the lateral aspect of the ramus and the coronoid process of the
      Origin: inferior border and medial surface of zygomatic arch.
      Insertion: lateral surface of ramus of mandible and its coronoid process.
      Innervation: mandibular nerve via masseteric nerve that enters its deep surface.
      It elevates and protrudes the mandible, closes the jaws and the deep fibers retrude it.

The Lateral Pterygoid Muscle (N50, N51) HIGH YIELD!

      This is a short, thick muscle that has two heads or origin.
      It is a conical muscle with its apex pointing posteriorly.
      Origin: superior head—infratemporal surface and infratemporal crest of the greater wing of the sphenoid
   bone, inferior head—lateral surface of lateral pterygoid plate.
      Insertion: neck of mandible, articular disc, and capsule of temporomandibular joint.
       Innervation: mandibular nerve via lateral pterygoid nerve from anterior trunk, which enters it deep
      Acting together, these muscles protrude the mandible and depress the chin.
      Acting alone and alternately, they produce side-to-side movements of the mandible.

The Medial Pterygoid Muscle (N50, N51) HIGH YIELD!

      This is a thick, quadrilateral muscle that also has two heads or origin.
      It embraces the inferior head of the lateral pterygoid muscle.
      It is located deep to the ramus of the mandible.
      Origin: deep head—medial surface of lateral pterygoid plate and pyramidal process of palatine bone,
   superficial head—tuberosity of maxilla.
      Insertion: medial surface of ramus of mandible, inferior to mandibular foramen.
      Innervation: 'mandibular nerve via medial pterygoid nerve.
      It helps to elevate the mandible and closes the jaws.
      Acting together, they help to protrude the mandible.
      Acting alone, it protrudes the side of the jaw.
      Acting alternately, they produce a grinding motion.
Second word of warning: When at lab, make sure you can identify the Lateral and Medial Pterygoid Muscles
at all angles (i.e. lateral view, posterior view, etc.)

Learning Objectives #4 & #5

Understand the bony anatomy of the mandible and temporomandibular joint region. The temporomandibular
joint is very complex. The goal is to understand the articulation at this joint and the movements of this joint.

The Temporomandibular Joint (N14)

        This articulation is a modified hinge type of synovial joint.
       The articular surfaces are: (1) the head or condyle of the mandible inferiorly and (2) the articular
    tubercle and the mandibular fossa of the squamous part of the temporal bone.
       An oval fibrocartilaginous articular disc divides the joint cavity into superior and inferior
    compartments. The disc is fused to the articular capsule surrounding the joint.
       The superior synovial cavity is responsible for protrusion of the mandible and the inferior synovial
    cavity is where jaw depression takes place.
        The articular disc is more firmly bound to the mandible than to the temporal bone.
       Thus, when the head of the mandible slides anterior on the articular tubercle as the mouth is
    opened, the articular disc slides anteriorly against the posterior surface of the articular tubercle.

The Articular Capsule

        The capsule of this joint is loose.
       The thin fibrous capsule is attached to the margins of the articular area on the temporal bone and
    around the neck of the mandible.

Ligaments of the Joint (N14)

        The fibrous capsule is thickened laterally to form the lateral (temporomandibular) ligament. It
    reinforces the lateral part of this capsule.
        The base of this triangular ligament is attached to the zygomatic process of the temporal bone and the
    articular tubercle.
        Its apex is fixed to the lateral side of the neck of the mandible.
        Two other ligaments connect the mandible to the cranium but neither provides much strength.
        The stylomandibular ligament is a thickened band of deep cervical fascia.
      It runs from the styloid process of the temporal bone to the angle of the mandible and separates the
   parotid and submandibular salivary glands.
       The sphenomandibular ligament is a long membranous band that lies medial to the joint.
      This ligament runs from the spine of the sphenoid bone to the lingula on the medial aspect of the

Translation of the Temporomandibular Joint (p. 731)

       The two movements that occur at this joint are anterior gliding and a hinge-like rotation.
       When the mandible is depressed during opening of the mouth, the head of the mandible and articular
   disc move anteriorly on the articular surface until the head lies inferior to the articular tubercle.
       This permits simple chewing or grinding movements over a small range.
       Movements that are seen in this joint are: depression, elevation, protrusion, retraction and grinding.

Learning Objective #6

Start learning the branches off the maxillary artery in this region. The rest of this artery will be learned later.

Study Plate 36 on Netters (3rd Edition) and be able to identify at least the major branches of the maxillary
artery: The inferior alveolar artery, the deep temporal artery, and the middle meningeal artery. Remember
that the auriculotemporal nerve (V3) splits around the middle meningeal artery. If you can draw out the
branches of arteries by memory at least 3 times, you’re good to go.

Learning Objective #7

To be able to have a good 3-D understanding of the complex courses of nerves in this region. They are complex,
but very important. A good understanding of the nerves in this region is critical to anesthetic use in this region.

Alright. This is the part where you should take out your skulls and wires and be able to know where all the
nerves course, enter, etc. Focus on the Maxillary and Mandibular regions of the Trigeminal nerve as shown on
Netters Plates 41, 42, and 116.

The Maxillary Nerve (CN V2) (N41, 116)

       This is the intermediate division of the trigeminal nerve and is purely sensory.
       It arises from the trigeminal ganglion and runs anteriorly in the inferior part of the cavernous sinus,
   inferior to the ophthalmic nerve.
       This nerve leaves the middle cranial fossa through the foramen rotundum.
Branches of the Maxillary Nerve

      The meningeal branches arise from this nerve which it is still in the middle cranial fossa. These nerves
   supply the dura.
      Ganglionic branches arise within the pterygopalatine fossa and enter the pterygopalatine ganglion as its
   sensory root.
       The zygomatic nerve supplies the skin of the temple and the prominence of the cheek; and brings
   parasympathetic fibers to the lacrimal gland.
      Superior alveolar nerves (posterior, middle, anterior); the nasal branches; greater and lesser palatine

The Mandibular Nerve (CN V3) (N41, 116)

       This is a mixed nerve (sensory and motor) and contains all the motor fibers of the trigeminal nerve.
       This nerve descends to the foramen ovale and then passes through this opening in the middle cranial
       Just outside the foramen, the motor and sensory roots of the mandibular nerve unite and then CN V3
   divides into anterior and posterior divisions.

Branches of the Mandibular Nerve

       From the nerve; nerve to medial pterygoid, tensor tympani and tensor veli palatini.
      From anterior trunk; buccal nerve, sensory, supplies cheek and mandibular buccal gingiva; and the
   motor branches to the muscles of mastication.
       From the posterior trunk; inferior alveolar nerve, lingual nerve (sensory and taste of anterior 2/3 of the
   tongue-taste fibers from chorda tympani) and auriculotemporal nerve (encircles the middle meningeal
   artery and with postsynaptic fibers of CN IX pass to the parotid gland).

Learning Objective #8

To define the venous drainage pattern.

Dr. McLoon just wants you to know that there’s a pterygoid plexus of veins (N66) that surrounds the lateral
pterygoid and drains into the maxillary vein (and internal jugular v.), the deep facial vein to facial vein (to
internal jugular v.), connections around mandibular nerve through the foramen ovale to cavernous sinus in the
skull, and the middle meningeal through foramen spinosum into the skull. I think the most important thing to get
out of here is that veins connect with sinus and know how they do it.

Clinical Correlation: As Dr. Mcloon mentioned, infections from the sinuses can travel into the cavernous
sinus via the facial vein.

Learning Objective #9

To begin to think about the use of nerve blocks: where the nerve is and where the anesthesia will be.

Basically know that if you want to repair or remove the mandibular teeth, you have to perform an inferior
alveolar nerve block. The site of the anesthetic injection is at the entrance to the mandibular canal at the
mandibular foramen. This should numb all the mandibular teeth, skin and mucosa of the lower lip, and the
mucosa, gingival, and skin of the chin. In Moore and Daly (p. 861 blue box), they caution NOT to insert the
needle too far posteriorly, or else you’ll enter the parotid gland, anesthetize the branches of the facial nerve, and
cause transient unilateral facial paralysis. Not good. On the other hand, if you inject superiorly in a mandibular
nerve block, administered superior to the inferior alveolar nerve block, the entire distribution of the mandibular
nerve will be blocked.

Also, be sure to know the difference between a mandibular nerve block and a maxillary nerve block. There were
some excellent slides in lecture illustrating which areas are numbed when you do each of these blocks. These
are favorite sources for exam questions.
                            Skull and Intracranial Fossa 1 and 2
Holes in the Head

CranialFossa        Bone                      Hole                                      Contents
Anterior       Ethmoid     Foramina of Cribiform Plate                 Olfactory (CNI) nerve bundles
Middle                                                                 CN II
               Sphenoid    Optic Canal
                                                                       Ophthalmic Artery

                                                                       CN III
                                                                       CN IV
                           Superior Orbital Fissure** (All nerves to   Lacrimal, frontal, and nasociliary
                           eye except CN II)                           branches of CN V1
                                                                       CN VI
                                                                       Ophthalmic Veins

               Sphenoid    Foramen Rotundum                            CN V2
                                                                       CN V3
               Sphenoid    Foramen Ovale                               Lesser Petrosal Nerve
                                                                       Accessory Meningeal Artery

                                                                       Middle Meningeal Artery, Vein, and
               Sphenoid    Foramen Spinosum
                           Foramen Lacerum                             EMPTY (sort of—see below)
                                                                       Carotid Artery
               Temporal    Carotid Canal
                                                                       Sympathetic Nerves

               Temporal    Hiatus of the …                             Lesser Petrosal Nerve
               Temporal    Hiatus of the …                             Greater Petrosal Nerve
Posterior                                                              CN VII
               Temporal    Internal Acoustic Meatus                    CN VIII
                                                                       Labyrinthine Artery

                                                                       CN IX
               Occipital   Jugular Foramen
                                                                       CN X
                                                                        CN XI
                                                                        Internal Jugular Vein
                                                                        Sigmoid Sinus

              Occipital       Hypoglossal Canal                         CN XII
                                                                        Medulla of Brain Stem
              Occipital       Foramen Magnum                            CN XI
                                                                        Vertebral Arteries

Bones of the skull and corresponding landmarks

The skull is a total of 21 fused bones in the skull + the 1 mandible + 6 auditory ossicles

8 Cranial Bones (calvarial)
These bones enclose the brain.

1) Frontal — Supraorbital Notch, sinus
2) Occipital — External Occipital Protuberance and Foramen Magnum
3) Ethmoid — Middle and Superior Concha, and Cribiform Plate
4) Sphenoid— Great and Lesser wings, Sella turcica, Sphenoid sinus, Medial and Lateral plates of pterygoid
process, pterygoid hamulus
5) and 6) Paired Temporal — Squamous and Petrous parts, Zygomatic Process, External acoustic meatus,
Mastoid process, Mandibular Fossa, Styloid Process
7) and 8) Paired Parietal

14 Facial Bones
1) and 2) Paired Lacrimal
3) and 4) Paired Nasal
5) and 6) Paired Palantine — Perpendicular and Horizontal plates
7) and 8) Paired Inferior Turbinate (Nasal Concha)
9) and 10) Paired Maxillary — Incisive Fossa, Incisive Canal, Palantine Process, Alveolar Process, Zygomatic
Process, Frontal Process
11) and 12) Paired Zygomatic
13) Vomer
14) Mandible — Mental Foramen

Skull Development

       Fontanels are the areas of membrane in babies where the skull bones have not yet fused together. When
   they fuse together, they form the sutures in the adult skull.
       Know the following fontanels:
               Anterior Fontanel
               Posterior Fontanel
               Sphenoid Fontanels (2)
               Mastoid Fontanels (2)

Other Important Skull Features


       Sagittal - defined in the midline of the body
       Coronal - between the frontal and parietal bones
       Lambdoid - between the parietal bones and occipital bone
Other landmarks

       Bregma - junction of the coronal and the saggital sutures
       Lambda - junction of the saggital and occipital sutures(looks like a greek letter Lambda)
       Pterion - thin part of the cranium over the middle meningial artery
Skull and Meninx Layers
The following are in order from most superficial to deepest.

1. Outer lamina (compact bone)
2. Diploe (spongy bone)-site of potential spread of infection from scalp to brain
3. Inner lamina (compact bone)
4. Potential epidural space
5. Dura Mater (periosteal and meningeal spaces)-contains venous sinuses between layers and septa
6. Potential subdural space
7. Arachnoid-layers connected by cisterns and trabeculae (avascular)
8. Subarachnoid Space (contains CSF and arachnoid trabeculae)
9. Pia Mater-large cerebral arteries and veins found here (vascular)
10. Brain surface
Arteries of the cranium (Circle of Willis)

Branches of the internal carotid artery

       Hypophyseal a.
       ophthalmic a.
       anterior choroidal a.
       posterior communicating a.
       anterior cerebral a.
       anterior communicating a.
       middle cerebral a. - remember the location under the pterion and the ease of trauma due to the thin bone
Branches of the vertebral artery
      Anterior and posterior spinal arteries
      posterior inferior cerebellar artery
      basilar a.
                Posterior Cerebral arteries

The cavernous sinus

      Is perforated by (i.e., what passes through):
                Interior Carotid Artery
                Abducens Nerve (CN VI)
      Contains within the wall:
                CN III
                CN IV
                CN V1
                CN V2
Other vessels

      Ophthalmic Artery = Optic Canal
      Ophthalmic (optic) Vein = Superior Orbital Fissure

Dural Septa and Venous Sinuses

       Septa: Falx cerebri (separates hemispheres) , tentorium cerebelli (separates cerebellum from cerebral
   cortex), falx cerebelli (separates cerebellar hemisheres), diaphragma sella (covers the pituitary gland)
      Venous Sinuses (drain into internal jugular vein):
Flow of CSF

      Cerebral Spinal Fluid (from Choroid Plexus)
      → Subarachnoid space
      → Arachnoid granulations
      →Dural Venous Sinuses
      →Cerebral Veins
      →Emissary Veins

Other Helpful Hints

      Divisions of Trigeminal exit the skull according to ―Standing Room Only‖
              S = Superior Orbital Fissure
              R = Foramen Rotundum
              O = Foramen Ovale
      No cranial nerves of the Middle Cranial Fossa exit any bone except the sphenoid (CN II—VI)
      CN XI passes through two foramina (Enters and leaves skull):
              Foramen Magnum = Spinal roots of accessory nerves
              Jugular Foramen = Exit of CN XI
Lecture material for the second lecture is a review of the cranial nerves

Bones of the Orbit

                sphenoid (lesser wing)
       Lateral wall:
                sphenoid (greater wing)
       Medial wall:

Openings of the Orbit
   1. supraorbital foramen
   2. optic foramen
   3. superior orbital fissure
   4. inferior orbital fissure - opens into pterygopalatine fossa, continuous w/ infraorbital groove, canal &
   5. anterior ethmoidal foramen
   6. posterior ethmoidal foramen
   7. nasolacrimal canal
   8. zygomatic foramen - seen as two, gives rise to facial and temporal
The Eyelid

      Skin is continuous until it becomes the conjuctiva on the inner surface of the eyelid which ascends and
   descends to the fornixes and covers the sclera.
      Orbital septum fibrous structure that anchors eyelid to bone
       Tarsal plate gives rigidity (anchored by medial, which divides around the lacrimal sac and lateral
   palpebral ligaments) and contains tarsal gland secrete waxy substance.
      Levator palpebra superioris tendon
      Orbicularis Oculi – innervated by Facial Nerve (CN VII)

              CN VII - closes the eye; imagine 7 as a hook attached to the upper lid pulling it down.
              CN III - holds eye open; imagine the roman numeral III as columns keeping the eye open.
      Tarsal muscles are innervated by the sympathetic nervous system (SNS) aid in opening the eye. (along
   with levator palpebra superioris (CN III))
              Clinical application: If the SNS innervation to the eye is damaged there will be drooping of the
      eyelid, so called ptosis. The eye will not completely close because of levator palpebra superioris. This is
      one of the 3 symptoms of Horner's syndrome (ptosis, miosis, & anhydrosis)
Lacrimal System

      Lacrimal gland sits on superior and lateral portion of eye
       Fluid picked up by the lacrimal caniculi (easy points if they have a pipe cleaner through it on the lab
      Fluid drains into lacrimal sac
Path Light Travels Through The Eye

Light source cornea (major focusing tool) anterior chamber          iris   pupil    posterior chamber   lens (fine
tuning tool) vitreous chamber neural retina

      Clinical note: inadequate drainage of the aqueous humor       high pressure    glaucoma
Involuntary Muscles

         Iris sphincter - closes pupil, parasympathetics using the ciliary ganglia
         Iris dilator - it dilates…I know...difficult, Sympathetic Nervous system (Superior cervical ganglia)
        Ciliary m. - when it’s relaxed the lens is stretched (far vision), contracts the lens thickens (parasymp -
   ciliary ganglia) (near vision). ACCOMODATION!
Extraocular Muscles

High Yield!
Innervation: LR6SO4, 3

         Rectus mm.
                Superior (CN III) – gaze      elevate/adduct pupil
                Inferior (CN III) – gaze     depress/adduct pupil
                Lateral (CN VI) – gaze      pupil laterally
                Medial(CN III) – gaze       pupil medially

         Oblique mm.
                Superior (CNIV) – gaze       inferiorly/abduct pupil [on top of inferior oblique when dissecting
         from above]
         (back of orbit   medial orbit     passes through trochlea     onto superior surface of eye)
                Inferior (CN III) – gaze     superiorly/abduct pupil

      Optic (CN II) retina ganglion cells optic nerve           optic foramen      middle cranial fossa    optic chiasm
     optic tract synapse in visual parts of brain
       Oculomotor (CN III)       superior orbital fissure     superior/inferior divisions somatic motor      innervates
   5 eye muscles
      Parasympathetic division follow sup. branch ciliary ganglia               post. ganglion     around sclera
     ciliary m. & iris sphincter m. (near vision/close pupil)
       Trochlear (CN IV) only nerve comes from post. brain stem           wall of cavernous sinus      superior orbital
   fissure orbit sup. oblique m.
         Abducens (CN VI) inside cavernous sinus        superior orbital fissure     orbit   lateral rectus m.
      Ophthalmic division of Trigeminal (V1) (ALL SENSORY) wall of cav. sinus                  sup. orb. fissure   orbit
     3 branches lacrimal, frontal, nasociliary nn.
                Lacrimal n. thru lacrimal gland     innervates lateral side of eye and eye lid
                Frontal n. branches into supratrochlear/supraorbital nn.
               Nasociliary n. innervates eye, goes medially and branches into post./ant. ethmoidal nn. thru
       respective foramina into anterior cranial fossa. Ant. ethmoidal n. ends on the outside of the nose and
       inside nasal cavity. Nasociliary n. continues as the infratrochlear n. through the inf. eyelid and part of
       Parasympathetic Innervation to Lacrimal Gland covered in next lecture

Synapse at the superior cervical ganglion and hop on the carotid post. ganglion go through orbit and jump on
to the short ciliary n. pass but do not synapse through ciliary ganglion innervate iris dilator m. and tarsal m.
(if a patient loses this, sphincter is unopposed and they will have droopy eye lids i.e. spinal cord injury,
Horner’s syndrome).


       Arterial - from internal carotid ophthalmic a. branches with all of the nerves mentioned previously
   (central artery of retina w/ optic n. encased w/in nerve). Central artery of retina is a functional end artery
   any occlusion death of what it supplies.
      Veins – 3 major drainages central vein of retina, superior/inferior ophthalmic vein. All drain into
   cavernous sinus. Veins of orbit anastomose with veins of face (no valves either…infections can flow
   backwards). Don’t pop your pimples or you’ll get meningitis.

                            Oral Cavity and Submandibular Region
Oral cavity boundaries

       Oral vestibule – area surrounding the teeth, bounded by buccal gingiva, lips, and cheeks
       Oral cavity proper – area between superior and inferior dental arches
       Anterior and lateral – maxillary and mandibular alveolar arches
       Superior – palate
       Posterior – continuous with oropharynx
       Isthmus of the fauces – constricted space connecting oral cavity and oropharnyx
               palatoglossal arch (anterior)
               palatopharyngeal arch (posterior)
               tonsillar fossa – between 2 arches, contains palatine tonsil

mobile, muscular folds around the mouth
               Perfusion                                                                       Innervation

Upper lip      superior labial a. (from facial a.) and infraorbital a.                         infraorbital n.
Lower lip        inferior labial a. and mental a.                                                  mental n.


Quiz yourself on the parts of the tooth                         Universal tooth numbering system

         Each half jaw contains:
            Total                  Incisors         Canines     Premolars     Molars

Children 20 primary teeth          2 (6, 8 mo)      1 (10 mo) none            2 (20-24 mo)

Adults      32 secondary teeth     2 (7-8 yr)       1 (10 yr)   2 (9-11 yr)   3 (6 yr, teens, late teens/early 20’s)

         Perfusion – superior and inferior alveolar aa. (from maxillary a.)
         Innervation – superior (from V2 maxillary n.) and inferior (V3 mandibular n.) alveolar nn.

fibrous tissue covered with mucous membrane

         Gingiva proper – keratinized, attached to alveolar processes of jaws and necks of teeth
         Loose gingiva – nonkeratinized, alveolar mucosal
                                                 Gingival innervation:
Local anesthetics

         There are several levels of anesthesia in dental work:
                 Infiltration – affects 1 tooth
                 Field block – affects a few teeth, diffusion of local anesthetic injected into tissue
                 Nerve block – injection local anesthetic is used to stop impulse conduction along a nerve
      McLoon’s favorite nerve block last year was the inferior alveolar n. The anesthetic is injected into the
   mandibular foramen where the inferior alveolar n. exits the foramen. This also affects the nearby lingual n.

Dental diseases

         Caries – bacterial decay of hard tissue of teeth (enamel and dentine)
         Pulpitis – untreated caries that has extended to the dental pulp
         Impacted wisdom teeth – incomplete eruption of 3rd molars
         Gingival recession – gums withdraw to expose the cementum of the tooth root
         Gingivitis – inflammation of the gums
         Periodontitis – untreated gingivitis progresses to surrounding tooth tissue and loosens teeth

covered with tightly bound mucosal over mucosal glands

Hard palate – bony region forming anterior roof of mouth

                 Palatine processes of maxillary bone (anterior)
                 Horizontal processes of palatine bone (posterior)
                Incisive foramen for nasopalatine n. (anterior)
                Greater palatine foramina for greater palatine n., a., and v. to hard palate (posterior)
                Lesser palatine foramina for lesser palatine n., a., and v. to soft palate (very posterior)
Soft palate – moveable region posterior to hard palate, no bony skeleton

         Loose mucosal
         Palatine aponeurosis – dense connective tissue
         Fibromuscular tissue
         Muscles of soft palate: (table below)
Muscle              Origin                        Insertion                    Innervation    Action

                    petrous part of temporal                                                  elevates palate during
Levator veli                                                                   X, cranial
                    bone and cartilage of         palatine aponeurosis                        swallowing and
palatini                                                                       root of XI
                    auditory tube                                                             yawning

                    scaphoid fossa of medial      (around hamulus of
                                                                                              tenses soft palate,
Tensor veli         pterygoid plate, spine of     medial pteryogid plate)
                                                                               V3             opens auditory tube
palatini            sphenoid, cartilage of        palatine aponeurosis of
                                                                                              during swallowing
                    auditory tube                 contralateral m.

                                                                                              depresses soft palate,
                                                                               X, cranial
Palatoglossus       palatine aponeurosis          side of tongue                              pulls pharyngeal walls
                                                                               root of XI

                                                                                              pulls wall of pharynx
                 hard palate and palatine                                      X, cranial     superiorly, anteriorly,
Palatopharyngeus                                  wall of lateral pharynx
                 aponeurosis                                                   root of XI     medially during

                                                                               X, cranial
Musculus uvulae palatine aponeurosis              Mucosal of uvula                            pulls uvula superiorly
                                                                               root of XI

                                 Palate arterial supply and sensory innervation:

                         Perfusion                                                          Innervation

anterior hard palate     greater palatine a.                                                nasopalatine n. (V2)

hard palate              greater palatine a.                                                greater palatine n. (V2)

soft palate              lesser palatine a., ascending palatine a. (from facial a.)         Lesser palatine n. (V2)


         Sulcum terminalis – divides root of tongue from body of tongue
       Lingual papillae
                Filiform – long, anterior 2/3 tongue, touch
                Fungiform – among filiform papillae, taste buds
                Vallate – large, anterior to sulcum terminalis, studded with taste buds
       Foramen cecum: pit in center of tongue, remnant of embryonic thyroglossal duct
       Root – thick mucous membrane, no lingual papillae, contains lingual tonsils
       Inferior to tongue:
                Lingual frenulum in center
                Submandibular duct terminates in sublingual caruncle
                Sublingual ducts in sublingual folds
                Deep lingual aa. and vv. on bottom surface of tongue → great for sublingual drug absorption,
       e.g. nitroglycerine

       Extrinsic tongue muscles:
                Origin                       Insertion                     Innervation Action

                superior mental spine of     dorsum of tongue and
Genioglossus                                                               XII        protrudes tongue anteriorly
                mandible                     hyoid bone

                body and greater horn of     side and inferior part of
Hyoglossus                                                                 XII        depresses and retracts tongue
                hyoid bone                   tongue

                                             side and inferior part of                retracts tongue, pulls sides of
Styloglossus styloid process                                               XII
                                             tongue                                   tongue up

                NOT A TONGUE

       Intrinsic tongue muscles:
                Superior longitudinal m. – pushes apex against palate
                Inferior longitudinal m. – pushes apex inferiorly
                Transverse mm. – narrows and thickens tongue
                Vertical mm. – protrudes tongue
       Arterial supply – branches of lingual a., which passes medial to hyoglossus
                Dorsal lingual a. – posterior tongue and palatine tonsil
                Deep lingual a. – anterior tongue
                Sublingual a. – floor of mouth, inferior tongue, sublingual gland

       Innervation of the tongue:
Salivary glands

      Submandibular gland:
             Duct runs between mylohyoid and hyoglossus, crosses lingual n.
             Opens via sublingual caruncle near midline at lingual frenulum
      Sublingual salivary glands:
             Inferior to tongue on either side of frenulum
             Drain via small ducts in sublingual folds and accessory duct into submandibular duct
             Preganglionic fibers: superior salivary nucleus → facial n. → chorda tympani → with lingual n.
             Synapse in submandibular ganglion
             Postganglionic fibers: to glands

                                 Autonomics of Head and Neck
Neuronal Modalities


      Somatosensory: pain, temperature, muscle tendon stretch
             involve neurons with cell body in sensory ganglion- located near CNS
             peripheral process: picks up sensory info
             central process: carries info to brain
             action potentials heading in
      Visceral Sensory: BP, gut, other viscera
             similar to somatosensory
      Special senses: each different

      Motor neurons
              responsible for movement
              innervate muscles
              cell bodies located within CNS-> send axons out-> synapse w/ muscle
              action potentials heading out
              activity in neurons make muscles contract
              two neuron system
                     preganglionic neuron: cell body in CNS (brain or spinal cord)
                     ganglionic neuron: cell body in autonomic ganglion
                     cell bodies in thoracic and lumbar spinal cord
                     ganglia near CNS
                     Head: cells in upper thoracic cord
                             axons leave cord via ventral root and join sympathetic chain
                             axons ascend in sympathetic chain and synapse at superior cervical ganglion
                             postganglionics travel on anything and everything (other nerves, carotid, etc. and
              follow arterial system through head)
                     cell bodies in brainstem or sacral spinal cord (cranial-sacral system)
                     ganglion near effector organ (structure it is controlling)

                               Sympathetics                        Parasympathetics

                   originate in upper thoracic spinal cord originate with III, VII, IX, or X

                   short pregangiolic neuron               long preganglionic neuron

                   ascends to head via sympathetic chain promiscuous course (jump around)

                   synapse in cervical ganglia             synpase in local ganglia

                   long postganglionic neuron              short postganglionic neuron


Ciliary ganglion

      Originate in accessory oculomotor nucleus (edinger-westphal)
      Travel via CNII
             axons exit via oculomotor n. from brain
             runs through middle cranial fossa in wall of cavernous sinus
             passes through superior orbital fissure
             branches-> inferior branch carries parasympathetic root to ciliary ganglion
      Preganglionics synapse in ciliary ganglion
             Travel via short ciliary nn. to eye
             runs in coroid to front of eye
      Postganglionics synapse in:
             ciliary muscle → contraction → thicken lens → close vision
             iris sphincter → contraction → close pupil → close vision
Pterygopalatine ganglion

      Originate in superior salivatory nucleus
      Travel via CNVII
             enters temporal bone through internal acoustic meatus
             travels through geniculate ganglion (no synapse)
             travels through hiatus of greater petrosal n.
             runs across floor of middle cranial fossa
             joins deep petrosal (carrying sympathetics from internal carotid)
             becomes n. of pterygoid canal
      Preganglionics synapse in pterygopalatine ganglion
             Travel via branches of V2 and V1 to lacrimal gland
                    Postganglionics synapse in lacrimal gland → salivation
             Travel via nasopalatine n. and others to nasal mucosa and paranasal sinuses
                    Postganglionics synapse in mucosa → ↑ secretion & fluidity
             Travel via greater and lesser palatine nn. to palate mucosa (hard and soft)
                    Postganglionics synapse in mucosa → ↑ secretion
Submandibular ganglion

      Originate in superior salivatory nucleus
      Travel via CNVII
             enters temporal bone through internal acoustic meatus
             travels through geniculate ganglion (no synapse)
             gives off chorda tympani
             exits skull via pterotympanic fissure and joins lingual n.
      Preganglionics synapse in submandibular ganglion
             Travel via lingual n.
      Postganglionics synapse in submandibular & sublingual glands → ↑ secretion & fluidity
Otic ganglion

      Originate in inferior salivatory nucleus (lower brainstem)
      Travel via CNIX
                exits skull via jugular foramen (along w/CNX, CNXI, and internal jugular v.)
                pass through superior and inferior ganglion of IX
                tympanic n. branches
                passes through tympanic plexus
                travels along floor of middle cranial fossa
                becomes lesser petrosal n.
                travels through infratemporal fossa
      Preganglionics synapse in otic ganglion
                Travel via auriculotemporal n.
      Postganglionics synapse in parotid gland → ↑ secretion & fluidity


Cervical ganglion

      Originate in intermediolateral cell column in upper thoracic cord
      Travel via ventral root-> white rami-> sympathetic chain
      Synapse in superior cervical ganglion
       Travel via internal carotid and a variety of nerves (e.g. short and long ciliary n.; sometimes with
   parasympathetics, sometimes not)
      Postganglionics synapse in:
                iris dilator → contraction → opens pupil → far vision
                superior & inferior tarsal mm. → contraction → opens eyelid
                blood vessels → vasoconstriction
                sweat glands → ↑ secretion
                hair of head and face → piloerection
                salivary glands → ↓ secretion & ↑ viscosity
                mucosa of respiratory and alimentary tracts → ↓ secretion
                heart → ↑ contractility → ↑ stroke volume → ↑ cardiac output
                                          Pharynx and Larynx
The pharynx functions in respiration and ingestion and is divided into three sections: nasopharynx, oropharynx,
and laryngopharynx. The nasopharynx is posterior to the nasal cavity and superior of the oral cavity. The
oropharynx is from the back of the oral cavity down to the larynx. The laryngopharynx is the lowest area dorsal
to larynx.


           Border                                               Structures

Inferior                    Soft Palate

Superior/Posterior          Sphenoid and Occipital bones, Sup. constrictor muscle

Lateral                     Auditory tube, Torus tubarius

Structures found in the nasopharynx: choanae (openings to nasal cavity), auditory tube, torus tubarius,
pharyngeal tonsil, salpingopharyngeal fold, pharyngeal tonsil, salpingopharyngeal fold.
       Auditory Tube:
              medial 2/3 is cartilagenous
              lateral 1/3 is bony
              function: to equalize pressure between the middle and outside ear
       levator veli palatini: origin: floor of auditory tube and petrous ridge of temporal bone; insertion: soft
       tensor veli palatini: origin: cartilage of auditory tube and medial pterygoid plate
Fun Fact: you pop your ears by contracting the tensor veli palatini and salpingopharyngeus and levator palatini
to open up the auditory tubes (also open when you swallow)


              Border                                                   Structures

Inferior                             Epiglottis & larynx

Superior                             Soft palate

Posterior                            wall of throat

Anterior                             terminal sulcus

Structures found in the oropharynx: back of the tongue, lingual tonsil, palatoglossal fold, palatopharyngeal
fold, salpingopharyngeal fold, palatine tonsil

       Vascular supply from: lesser palatine a., ascending pharyngeal a., facial a., lingual a.
       Waldeyer's ring:lymphoid tissue
              pharyngeal tonsil
              palatine tonsil
              tubal tonsil
              lingual tonsil

Structures found in the laryngeopharynx: Epiglottis, epiglottic valleculae (little valleys at base of tongue),
pyriform recess (swallowed foreign bodies may be lodged here), circumferential muscles: superior, middle, and
inferior pharyngeal constrictors (superficial; overlap like shingles), longitudinal muscles: palatopharyngeus,
salpingopharyngeus (luminal side), stylopharyngeus (this muscle along with CN IX passes between superior
and middle constrictors).
Note: Understand that while swallowing voluntary muscles do the work initially but then gradually involuntary
muscles take over the process (larynx is elevated; pharynx is widened).
       Muscle                  Origin                    Insert                               Function

Circumferential mm

                       Medial Pterygoid Plate,
Sup. Pharyngeal                                Median Pharyngeal
                       pterygomandibular                                 CN X
Constrictor                                    Raphe

Mid. Pharyngeal        Greater and Lesser      Median Pharyngeal
                                                                         CN X
Constrictor            Horns of Hyoid          Raphe

                       Oblique line of thyroid
Inf. Pharyngeal                                Median Pharyngeal
                       cartilage, cricoid                                CN X
Constrictor                                    Raphe

Longitudinal mm

                                                                                       Elevates pharynx,
Salpingopharyngeus     Medial Auditory Tube    Palatopharyngeus m        CN X
                                                                                       opens auditory tube

                                                                                       Constricting pharynx,
                       Aponeurosis of Soft     Dorsal border of Thyroid                depresses soft palate,
Palatopharyngeus                                                        CN X
                       Palate                  Cartilage                               elevates pharynx and

                                                                                       Elevates sides of
                       Aponeurosis of Soft
Palatoglossus                                  Posterior Lateral Tongue CN X           tongue, depresses soft

                                                                                       Elevates pharyngeal
                                               Dorsal Border of
Stylopharyngeus        Styloid Process                                   CN IX         wall and thyroid
                                               Thyroid Cartilage

Intrinsic mm

                                                                                       Rotates thyroid
                       Anterior Cricoid                                  External
Cricothyroids                                  Inf. Thyroid Cartilage                  cartilage ant & inf,
                       Cartilage                                         laryngeal
                                                                                       tenses vocal folds

Lateral                Cranial margin of       Muscular Process of       Recurrent
                                                                                       Adducts vocal folds
Cricoarytenoids        Cricoid Cartilage       Arytenoids Cartilage      laryngeal

Transverse Arytenoids Posterior concave        Post concave surface of   Recurrent     Adducts vocal folds
                     surface of arytenoids    arytenoids cartilage of    laryngeal
                     cartilage                opposite side

                     Muscular process of      Apex of arytenoid          Recurrent
Oblique Arytenoids                                                                       Adducts vocal folds
                     arytenoids cartilage     cartilage of opposite side laryngeal

Posterior            Posterior cricoid        Muscular process of        Recurrent       Abduction of vocal
Cricoarytenoids      cartilage                arytenoids cartilage       laryngeal       folds

                                                                                         Relaxes vocal folds,
                     Inside lamina of thyroid Lateral margin of          Recurrent
Thyroarytenoids                                                                          antagonist of
                     cartilage                arytenoids cartilage       laryngeal

                     Inner surface of thyroid Vocal process of           Recurrent       Relaxes vocal
                     cartilage                arytenoids cartilage       laryngeal       ligaments


                                                         Surface features
                                                         epiglottis, vestibule, aryepiglottic folds, false vocal
                                                         cords (a.k.a. ventricular fold), ventricle, true vocal
                                                         folds, vocal ligaments, rima glottidis

                                                         Palpable landmarks

                                                                 hyoid bone
                                                                 thyroid cartilage
                                                                 cricothyroid ligament
                                                                 cricoid cartilage
                                                         Artery / Nerve Pairings

                                                                 Superior laryngeal artery runs with internal
                 laryngeal nerve
         Inferior laryngeal artery runs with recurrent
                 laryngeal nerve
                Nerve                                    Innvervates                Type

Internal laryngeal n                  True vocal cords                 Sensory

External laryngeal n                  Cricothyroid m                   Motor

Recurrent laryngeal n                 All other portions of larynx     Sensory and Motor

CN X and symp trunk                   Smooth muscle                    Autonomics

Unpaired cartilages

         thyroid cartilage
         crycoid cartilage
Paired cartilages

         arytenoids cartilages
         corniculate cartilages
         cuniform cartilages

         thyrohyoid membrane
         cricothyroid lig.
         vocal lig.
         vestibular lig.
       conus elasticus (cricovocal lig.)
Extrinsic muscles

       infrahyoid and suprahyoid
Infrahyoid muscles

       3 adductors (speech):
               lateral cricoarytenoids
               oblique arytenoids
               transverse arytenoids.
       1 abductor (breathing)
               posterior cricoarytenoids
       1 tensor
       2 relaxers
       1 vocal ligament
               ummm, self descriptive

Review Questions

1) Damage to the external laryngeal nerve during thyroid surgery could result in the inability to

       a. relax the vocal cords
       b. rotate the arytenoid cartilages
       c. tense the vocal cords
       d. widen the rima glottidis
       e. abduct the vocal cords
2) If the patient is unable to abduct the vocal cords during quiet breathing, which of the following muscles is

       a. Vocalis m.
       b. Cricothyroid m.
       c. Oblique arytenoid m.
       d. Posterior cricoarytenoid m.
       e. Thyroarytenoid m.
3) Which of the following pairs of muscles is most instrumental in preventing food from entering the larynx and
trachea during swallowing?

       a. Sternohyoid and sternothyroid mm.
       b. Oblique arytenoid and aryepiglottic mm.
       c. Inferior pharyngeal constrictor and thyrohyoid mm.
       d. Levator veli palatini and tensor veli palatini mm.
       e. Musculus uvulae and geniohyoid mm.

1) C
2) D
3) B (Remember that the vocal cords dominate the epiglottis in preventing food and other material from going
down the trachea)

External Ear

       external auditory meatus
       Auricle: external portion of ear; attached to side of head via: connective tissue, temporalis fascia,
   auricularus muscles, cartilage of ear (continuous with external auditory meatus)
       External features:
               outer fold- helix: terminates as crux of helix
               Inner fold- anti-helix, has crura
               Tragus- elevation anteriorly
               Anti-tragus: opposite to tragus; cartilaginous elevation
               Inter-tragic notch: between tragus and anti-tragus; depression
External Auditory meatus (EAM)

       2 ½ cm. long in adult
      conveys sound waves from auricle to tympanic membrane
      lateral 1/3: cartilaginous
      medial 2/3: bone
      isthmus: junctional area between cartilaginous and bony portions; narrowing
      lined with skin, has hair follicles, sebaceous glands, ceruminous glands (secrete waxy substance)
Tympanic Membrane

      fibrous disc
      separates external auditory meatus from middle ear cavity
      sits at an angle: more lateral on superior aspect and more medial on inferior aspect
      has ring of fibrocartilage that helps anchor inside meatus
      appears concave from external view
      Outer surface: covered with stratified squamous epithelium
      Inner surface: covered by thin layer of mucosa
The Middle Ear as a box(Netter 89A, 89B)

      lateral wall: convexity of tympanic membrane
      medial wall: promontory- bulge created by first turn of cochlea
      floor: jugular wall; bulb of internal jugular vein in floor
      roof: tagman tympani
      attic: epitympanic recess
      posterior wall: mastoid wall; behind it is the mastoid bone/mastoid air cells
      window: in mastoid wall; atidus(in communication with mastoid air cells) to mastoid antrum
      anterior wall: carotid wall; internal carotid a. near

      malleus(hammer: attached to inside of tympanic membrane) and incus(anvil) articulate with one
      stapes (stirrup): has oval base plate that fits over vestibular/oval window leading to inner ear
      sound waves vibrate tympanic membrane-> causes motion of malleus-> which is transferred to the incus
   and stapes-> and then conveyed to inner ear through articulation of stapes with vestibular window
      cochlear/round window: inferior to promontory

              formed by handle of malleus
              depression in tympanic membrane
The Inner Ear (Netter 90B, 90C)

      vestibulocochlear organ
         responsible for vestibular information (balance) and cochlear information (hearing)
Inner Ear Fluids

         There are two types of fluid

         chemically similar to cerebrospinal fluid
         fluid between membranous labyrinth and bony labyrinth
         high in Na+
         low K+

         fluid inside membranous labyrinth
         chemically similar to intracellular fluid
         high in K+
         low Na+
The Cochlea (Netter 91A, 91B)

         curled structure
         has 2 ½ turns
         bony core(houses sensory fibers coming back from cochlea)
         separated into 3 compartments:
                cochlear duct
                scala vestibuli
                scala tympani
The Labyrinth (Netter 90B, 90C, 91A, 91B)
Semicircular canals: posterior; at base of each canal is an ampula (dilation)

         canals respond to different directional rotations

         within membranous labyrinth in area of ampula
         specialized endothelial cells
         hair cells interspersed and embedded in gelatinous cap cupula – suspended in endolymph
         sensitive to rotational motion of head-> cupula deflected by endolymph
Vestibule: body of bony labyrinth

Membranous labyrinth
       soft, membranous passageway
       inside bony labyrinth
       similar to shape and structure as protective bony labyrinth
Labyrinthine a.: supplies blood to membranous labyrinth

Cochlear duct: membranous passageway inside cochlea

Semicircular ducts: membranous part inside semicircles

Utricle and Saccule: bulges inside vestibule

       have specialized endothelium: macula- contains row of columnar epithelium cells with specialized hair
   cells with cilia interspersed between and project into gelatinous layer (covered by otoconia: calcium-
   carbonate crystals)
      when tilt head-> otoconia shift and pull on gelatinous layer-> cilia deflect, causing depolarization of
   sensory cells that let brain know which direction head is tilted
      hair cells also sensitive to vertical pressure (e.g. moving up in an elevator; sense of gravitational
Sound travel

       when sound waves come into fluid of perilymph-> travel through scala vestibuli; pressure released
   through scala tympani (released through round window)
vestibular membrane: between scala vestibule and cochlear duct

basilar membrane: between cochlear duct and scala tympani; longer at apex of cochlea (responds to lower
frequency sounds)/ shorter at base of cochlea (responds to high frequency sounds)

spiral organ of corti: sensory structure in cochlea that allows us to hear; row of epithelial cells with
interspersed hair cells that project into gelatinous layer: tectorial membrane: firmly attached to spiral lamina

       sound waves -> scala vestibule -> vestibular membrane-> perilymph -> organ of cortide -> vibration of
   basilar membrane (vibration of cells causes depolarization)
       frequency of sound determines which part of the basilar membrane is going to vibrate

Superficial temporal a.

       branches to lateral auricle
       supplies cartilaginous portion of EAM
Posterior auricular a.

       branches to auricle
       inner surface of tympanic membrane
Deep auricular a.

        to bony region of EAM
        to outer surface of tympanic membrane
Anterior tympanic a.

        inner surface of tympanic membrane

Stapedius m.

        originates from pyramidal eminence
        travels to handle of stapes
        innervation: CNVII
Tensor tympani m.

        attaches to handle of malleus
        comes from anterior wall of middle ear cavity
      important for protecting mechanism of oscicles relating vibration to inner ear; protect ear from damage
   due to loud sounds
        innervation:CNV (V3)
               paralysis of stapedius from facial n. lesion-> hyperacusia: excessive acuteness of hearing


CNVII, CNX, CNIX, auriculotemporal branch of V3

        important for carrying sensory information back from EAM and tympanic membrane
CNVII, CNX(gag reflex), auriculotemporal branch of V3

        external portion of tympanic membrane and EAM

        middle ear
        internal portion of tympanic membrane
       tympanic n. carries presynaptic parasympathetic(continue through roof of middle ear cavity-> become
   lesser petrosal n., heading to parotid gland) and sensory fibers (spread out on middle ear cavity as tympanic
       gives off chorda tympani branch-> travels through tympanic cavity between malleus and incus

               bend in CNVII
               contains geniculate nucleus: contains cell bodies of sensory neurons
(at genu, also see branching of greater petrosal n.)

The Route of the Facial Nerve

       Internal Auditory Canal
       Geniculate Ganglion to the GSPN
       Tympanic Segment
       Second Genu at the Stapes
       Mastoid Segment
       The Stylomastoid Foramen
       Facial Branches

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