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Head and Neck SUPERFICIAL NECK

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					  Head and Neck 1: SUPERFICIAL NECK
    I.    Cervical Vertebrae
          a. General Features
                  i. Bodies are relatively SMALL when compared to thoracic and
                     lumbar
                 ii. Vertebral foramen are LARGE and triangular  to accommodate
                     the cervical enlargement of the spinal cord
                iii. Spinous processes are SHORT and often bifid (forked) except C7
                     which is quite long and palpable (VERTEBRAL PROMINENS)
                iv. Transverse processes have a foramen for the passage of the
                     vertebral artery  TRANSVERSE FORAMEN

                  Transverse foramen



               Body                              Body


                           Vertebral
Bifid                      foramen
                                                                 Vertebra
spinous
                                                                 prominens C7
process

          b. Transverse Processes
                 i. Trough shaped with groove for spinal nerve
                ii. End laterally in 2 small projections  ANTERIOR and
                    POSTERIOR TUBERCLES
          c. Articular Facets
                 i. Relatively horizontal (compared to thoracic and lumbar) allowing a
                    greater degree of motion in cervical region.
  Anterior                                                                Groove for
  tubercle                                                                Spinal nerve




                                 Posterior                             Articular
                                 tubercle                              facet
         II.    Atypical and Typical Cervical Vertebrae
                a. Atlas – Atypical cervical vertebrae
                        i. 1st cervical vertebrae
                       ii. Widest of all cervical vertebrae
                      iii. Has NO SPINOUS PROCESS or BODY
                      iv. Consists of 2 lateral masses connected by anterior and posterior
                           arch
                       v. Superior articular facets are kidney shaped and articulate with the
                           OCCIPITAL CONDYLES (skull)
                      vi. Anterior arch has a facet for articulation with DENS of AXIS (2nd
                           cervical vertebrae)
superior view
                                                                Anterior arch
of the atlas


                                             facet
                                             for dens


                        Superior
                        facet                                     Posterior arch


                b. Axis – Atypical cervical vertebrae
                       i. 2nd cervical vertebrae
                      ii. Distinguishing feature is the tooth-like DENS process that projects
                          superiorly from the body
                     iii. Large flat superior articular facet on which the atlas rotates
                     iv. Large BIFID spinous process for muscular attachments

                                                     Superior articular facet


       Dens




                                                                                    Bifid spinous process


      IMPORTANT: No IV Disks b/w C1 & C2 or b/w C1 and occipital bone
       c. Course of VERTEBRAL ARTERY
              i. Branch of SUBCLAVIAN
             ii. Passes through the transverse foramina of the cervical vertebrae
                 (EXCEPT C7)
            iii. At the ATLAS (C1) – enters the foramen magnum in the base of
                 the skull and helps vascularize the brain and spinal cord

III.   Craniovertebral Joints
       a. Atlanto-occipital Joint
               i. Condyloid type synovial joint
              ii. Between superior articular facet of the ATLAS (C1) and the
                  OCCIPITAL CONDYLES
             iii. Primarily flexion and extension in the saggital plane (“YES”
                  movements)
       b. Atlanto-axial Joint
               i. Actually 3 articulations
                     1. 1 median atlantoaxial joint – between DENS of C2 and the
                         anterior arch of C1 “pivot-type” synovial joint
                     2. 2 lateral atlantoaxial joints – between opposing articular
                         facets (zygapophysial – “gliding-type” synovial joint)
                     3. movement of all 3 articulations is mainly in the transverse
                         plane  “NO” movements
                     4. ATLANTO-AXIAL ROTATION = skull and ATLAS (C1)
                         rotate around the pivot of the DENS when the head is
                         turned.
IV.    Levels of Cervical Vertebrae with respect to external structures
       a. C1 = level of NOSE
       b. C2 = level of TEETH
       c. C3 = body of MANDIBLE
       d. C4 = Between HYOID BONE and THYROID CARTILAGE
       e. C5 = lower THYROID CARTILAGE
       f. C6 = level of CRICOID CARTILAGE
       g. C7 = just below the CRICOID

V.     Larynx
       a. Suspended form the hyoid bone
       b. Our phonating mechanism
       c. Located in the anterior neck between C4-C8
       d. Aside form voice production, guards and maintains a patent airway
       e. Consists of 3 major cartilages
               i. Thyroid (shield) cartilage
              ii. Epiglottic cartilage
             iii. Cricoid cartilage
       f. Trachea extends from the larynx to the thorax-air transport
       g. SEE Head and Neck 8 for more information
VI.   Other Structures of the Neck
      a. Thyroid gland
              i. Just anterior to the cricoid cartilage
             ii. Discussed further in Head and Neck 2
      b. Hyoid Bone
              i. Derived from 2nd and 3rd pharyngeal arches
             ii. “U”-shaped bone opposite C3/C4 vertebrae
           iii. Consists of a BODY, GREATER and LESSER HORNS
            iv. Does NOT articulate with any other bones
             v. Serves as attachment for HYOID MUSCLES
      c. Hyoid Muscles
              i. Steady and move the hyoid bone and larynx
             ii. Divided into 2 groups
                     1. Suprahyoid – located above the hyoid
                             a. Anterior belly of digastric – trigeminal nerve
                                 innervated (CN V3)
                             b. Posterior belly of digastric – facial nerve (CN VII)
                                 innervated
                             c. Mylohyoid – trigeminal nerve innervated (CN V3)
                             d. Sylohyoid – facial nerve innervated (CN VII)
                     2. Infrahyoid – located below the hyoid
                             a. Often referred to as the “strap muscles”
                             b. Sternohyoid
                             c. Sternothyroid
                             d. Omohyoid
                             e. Thyrohyoid – *C1 innervated*
                             f. Innervated by the motor portion of the cervical
                                 plexus (ansa cervicalis)  except thyrohyoid –
                                 innervated by C1)
         Mylohyoid
                                               Anterior digastric
                     3.
                            a.
                                                            Stylohyoid

                                                              Posterior
                                                              digastric



                                                                      Thyrohyoid




 Omohyoid                                              Sternothyroid
                      Sternohyoid
           d. Cervical Plexus
                  i. Formed by the ventral rami of C1-C4 spinal nerves
                 ii. The plexus has a sensory portion and a motor portion
                        1. Sensory Branches – provide cutaneous sensation to the
                            cervical region
                                a. Exit the posterior border of the SCM and provide
                                   cutaneous innervation to neck and shoulder regions
                                         i. Transverse cervical
                                        ii. Greater auricular
                                       iii. Lesser occipital
                                       iv. Supraclavicular nerves
                        2. Motor branches – form a large loop (ANSA
                            CERVICALIS) that innervates the infrahyoid muscles

                       SENSORY BRANCHES (CUTANEOUS)




           e. Sternocleidomastoid (SCM)
                   i. KEY to dissection  divides the neck into 2 triangles
                          1. ANTERIOR
                          2. POSTERIOR
                  ii. flexes the neck (acting bilateral)
                 iii. turns face opposite side (unilateral action)
                 iv. Innervated by the accessory nerve (CN XI)

ITC: Torticollis
   - Condition referred to as “wry neck” – head turned and tilted
   - Muscular torticollis – occurs when a fibrous tissue tumor (benign) forms within
       the SCM or the muscle is inadvertently torn during childbirth resulting in scar
       tissue/muscular contractions
-   Spasmodic torticollis – neurological disorder of abnormal tonicity on the SCM
    and/or trapezius muscles  generally appears during 20-60 years of age

VII.   Cervical Fascia
       a. Structures in neck are compartmentalized by layers of cervical fascia
       b. 4 layers of fascia
               i. Superficial cervical fascia
                      1. thin layer beneath the skin
                      2. contains the cutaneous nerves, blood vessels, lymphatics,
                          and fat
                      3. also contains the Platysma Muscle
                              a. superficial muscle found just beneath the skin
                              b. muscle of facial expression
                              c. Innervated by the facial nerve (CN VII)
                              d. Pulls the angles of the lips inferiorly and tenses the
                                  skin of the neck
              ii. 3 layers of Deep cervical fascia
                      1. Investing layer
                              a. Most superficial of the deep fascias
                              b. Attaches to the spinous process of the cervical
                                  vertebrae and forms a “tubular sheath” around the
                                  structures in the neck
                              c. The investing fascia splits and surrounds both the
                                  trapezius and SCM
                      2. Pretracheal layer
                              a. Extends from the hyoid bone superiorly and to the
                                  thorax (pericardium) inferiorly
                              b. Composed of 2 layers
                                       i. Muscular layer
                                              1. surrounds the infrahyoid muscles
                                                  (strap muscles)
                                      ii. Visceral layer
                                              1. encloses the thyroid gland, trachea,
                                                  and esophagus
                                              2. posterior extension of this visceral
                                                  layer is known as Buccopharyngeal
                                                  fascia
                                              3. Between Buccopharyngeal fascia
                                                  and prevertebral fascia is a space 
                                                  retropharyngeal space
                                                      a. Major pathway for the spread
                                                          of infection between the neck
                                                          and the thorax.
                      3. Prevertebral layer
                              a. Forms a tubular sheath around the vertebral column
                                  and the associated muscles
                                           b. This layer surrounds the intrinsic muscles of the
                                               spine along with the scalene and longus colli
                                               muscles  serve as flexors of the cervical vertebral
                                               column
                                           c. This fascia extends laterally as the axillary sheath
                                               that is seen around the brachial plexus
                                           d. REMEMBER: the scalene muscles surround the
                                               roots of the brachial plexus (upper limb 2)
                                           e. Fascia surrounding these muscles (prevertebral)
                                               contributes to the axillary sheath
                                    4. Carotid Sheath
                                           a. Tubular fascial sheath that receives contributions
                                               form the other layers of cervical fascia
                                           b. Houses 3 very important structures
                                                    i. Common Carotid Artey
                                                   ii. Internal Jugular Vein (IJV)
                                                  iii. Vagus Nerve (CN X)
                                    5. These layers or sheaths form natural cleavage planes for
                                       surgeons to separate and reflect tissues
                     c. These facial planes often determine the direction in which
                        infections/tumors can spread within the neck


       Muscular layer                                                                 SCM




  Visceral layer                                    trachea
                                       Thyroid
                                       gland                                                   Carotid sheath

Buccopharyngeal
fascia


Retropharygneal
space




                                                                                           Trapezius

   Investing layer
                                                              Prevertebral layer
VIII.   Cervical Triangles
        a. Anterior Triangle
                i. Boundaries
                      1. Inferior Border of Mandible
                      2. Midline of Neck
                      3. Anterior Border of SCM
               ii. Divided into 4 smaller triangles
                      1. Submandibular
                              a. Bounded by
                                      i. Inferior border of mandible
                                     ii. Anterior belly digastric
                                    iii. Posterior belly digastric
                              b. Contents include
                                      i. Submandibular gland
                                     ii. Fascial artery and vein
                                    iii. Hypoglossal nerve – CN XII
                      2. Submental
                              a. Bounded by
                                      i. Anterior bellies of the digastric
                                     ii. Hyoid bone
                                    iii. Myohyloid muscle forms the floor
                              b. Contents include
                                      i. Portion of the anterior jugular vein can be
                                         found within this triangle
                                     ii. Lymph nodes
                      3. Muscular
                              a. Bounded by
                                      i. Midline of the neck
                                     ii. Superior belly of omohyoid muscle
                                    iii. Anterior border of SCM
                              b. Contents include
                                      i. Infrahyoid muscles
                                     ii. Thyroid gland often considered within this
                                         triangle
                      4. Carotid
                              a. Bounded by
                                      i. Superior belly of omohyoid muscle
                                     ii. Anterior border of SCM
                                    iii. Posterior belly of the digastric muscle
                              b. Contents include
                                      i. Carotid Sheath (IJV, CN X and common
                                         carotid artery)
                                     ii. Ansa cervicalis can be found overlying
                                         carotid sheath
                                    iii. Hypoglossal nerve (CN XII)
          b. Posterior Triangle
                 i. Boundaries
                       1. Posterior Border of SCM
                       2. Clavicle
                       3. Anterior Border of Trapezius
                       4. Floor is covered by
                               a. Spenius Capitus (top)
                               b. Levator Scapulae Muscle
                               c. Scalene Muscles – anterior and middle scalenes
                                   with portion of posterior
                               d. Inferior belly of the Omohyoid Muscle
                       5. Contents
                               a. Coursing diagonally across the triangle is the
                                   accessory nerve (CN XI)
                               b. Additionally, the sensory branches of cervical
                                   plexus course across
                               c. Arising near the angle of mandible, the external
                                   jugular vein (EJV) is formed by the posterior
                                   auricular and retromandibular veins
                                       i. Courses inferiorly across the SCM and
                                          enters subclavian vein
                                      ii. Lies just deep to the platysma and is
                                          vulnerable to injury
                ii. Divided into 2 smaller triangles
                       1. Occipital (larger)
                       2. Supraclavicular or (subclavian) (smaller)

ITC: EJV Examination
   - Normal systemic venous pressure only SLIGHTLY distends the EJV’s on the
      neck
   - EJV’s can become quite prominent in the neck when systemic venous pressure
      rises
          o Heart failure
          o SVC obstruction
          o Increased intrathoracic pressure (tension pneumothorax)

   IX.    Accessory Nerve CN XI
          a. Has 2 roots/origins
                 i. Cranial Root – from the medulla
                ii. Spinal Root – from the upper cervical spinal cord
          b. Both roots fuse together and exit the skull via the jugular foramen
          c. CN XI then divides into internal and external ramus
                 i. Internal – joins vagus and innervated the larynx – consider it to be
                    a part of the vagus nerve
                ii. External – often referred to as the “spinal accessory nerve” which
                    innervates trapezius and SCM (somatic motor fibers)
BOTTOM LINE CONCEPTS:

   Vertebral arteries arises from the subclavians and ascends in the neck through the
    cervical vertebrae

   Cervical fascias help compartmentalize structures in the neck and form fascial
    planes that can determine the spread of infection

   Cervical plexus (C1-C4) consists of a motor portion- the ansa cervicalis- which
    innervates the infrahyoid muscles & sensory branches that innervate the skin of
    the neck/shoulder region

   Carotid sheath contains the vagus nerve (CN X), internal jugular vein & the
    carotid arteries

   Spinal accessory nerve exits the jugular foramen and innervates the SCM &
    trapezius muscles via somatic motor fibers

   External jugular vein can be used as an “external barometer” to evaluate a patients
    systemic venous pressure
Head and Neck 2: Deep Neck

   I.    Superior Thoracic Aperture
         a. Completely surrounded by skeletal elements
         b. Boundaries
                 i. Body of T1 superiorly
                ii. Medial margins of 1st ribs on either side
               iii. Manubrium of sternum anteriorly




         c. structures passing between the head and thorax pass up and down through
            superior thoracic aperture
         d. at the base of the neck, the trachea is immediately anterior to the
            esophagus
         e. esophagus in directly anterior to vertebral column
         f. there are major veins, arteries and nerves anterior and lateral to the trachea

   II.   Major Vessels in between thorax & head/neck
         a. Venous system – major vessels that return venous blood to heart
                 i. External jugular vein – drains blood from scalp and face
                ii. Internal Jugulars – drain through the neck
               iii. Subclavians – from the limbs  unite with internal jugulars @ the
                    “venous angle”
                       1. venous angle is where the major lymphatic vessels join the
                           systemic venous circulation
                       2. large thoracic duct unites with venous system @ left
                           venous angle
             iv. Right and left brachiocephalics – vein after union internal
                 jugular and subclavian @ “venous angle
              v. Superior vena cava – brachiocephalics join to form SVC

                              Internal jugular
                                                     Internal jugular

                          EJV
       Right
       subclavian


                                                                   Left subclavian

                                     SVC
Right brachiocephalic
                                                         Left brachiocephalic




       b. Arterial System – Major branches from the aortic arch
              i. Brachiocephalic Trunk – gives rise to:
                     1. right common carotid
                     2. right subclavian artery
             ii. Left common carotid
            iii. Left subclavian artery
               Right common
                                     Left common
       Right
       subclavian



                                     aorta                        Left
                                                                  subclavian
               BC Trunk
     iv. Common carotid system
           1. common carotid ascends within the carotid sheath with the
              IVJ and the vagus nerve
           2. the common carotids bifurcate @ approximate level of C4
              into the
                  a. internal carotid arteries
                            i. ascends into cranial cavity thru “carotid
                               canal” and provides vascular supply to eye
                               and brain
                  b. external carotid arteries – gives rise to numerous
                      branches within neck and head
                            i. Superior thyroid
                           ii. Lingual
                         iii. Facial
                          iv. Ascending pharyngeal
                           v. Posterior auricular
                          vi. Occipital
                         vii. Superficial
                        viii. maxillary



                       Facial artery




Lingual


              External                     Internal carotid
              carotid



  Superior
  thyroid
                                                                IJV

             Common
             carotid



                                       Vagus CN X
              c. Carotid bifurcation
                     i. Located at the carotid bifurcation, two
                        important receptors that closely monitor our
                        vascular system
                            1. Carotid body – an ovoid mass of
                                tissue that is an important
                                chemoreceptor that monitors blood
                                Oxygen levels (low Oxy increases
                                respiration and heart rate
                            2. Carotid sinus – slight dilation near
                                the bifurcation  it is a
                                baroreceptor that reacts to changes in
                                arterial pressure
                    ii. these receptors are innervated by branches
                        of the glossopharyngeal nerve (CN IX) and
                        the vagus nerve (CN X) via visceral
                        sensory fibers


v. Subclavian artery
      1. provide the major arterial supply to the upper extremity
      2. also provide some major branches that help vascularize
          structures within the neck
      3. additionally, they contribute significant supply to the brain
          and spinal cord
      4. Divided into 3 parts by the nearby scalene muscle
              a. 1st part – medial to muscle  3 major branches
                       i. Vertebral artery
                              1. ascends via the transverse foramina
                                 to the foramen magnum where it
                                 supplies brain and spinal cord
                      ii. Internal thoracic
                              1. descends along the thoracic wall
                                 (with long thoracic nerve??)
                     iii. Thyrocervical trunk
                              1. gives rise to 4 branches
                                     a. inferior thyroid – helps
                                         vascularize the thyroid gland
                                     b. suprascapular – posterior
                                         shoulder region
                                     c. tranverse cervical –
                                         trapezius
                                     d. ascending cervical - small
              b. 2nd part posterior to muscle
                       i. Costocervical trunk
                            c. 3rd part lateral to muscle
                                     i. Dorsal Scapular artery
                            d. Pneumonic = VIT C&D
                      5. continues as the axillary artery as it courses past the 1st rib

III.   Scalene Muscles
       a. Originate from transverse processes C2-C6
       b. Comprised of 3 muscles
               i. Anterior Scalene – inserts into 1st rib (scalene tubercle
              ii. Middle Scalene – inserts into 1st rib (posterior to anterior scalene)
             iii. Posterior Scalene – inserts into 2nd rib
       c. Innervation arises from brachial plexus

       d. Three important anatomical relationships concerning these scalene
          muscles
              i. Brachial plexus (roots) and subclavian artery course between the
                 anterior and middle scalene muscles
             ii. Subclavian vein courses anterior to anterior scalene muscle
            iii. Phrenic nerve (C3,4,5) lies on anterior surface of the anterior
                 scalene muscle

IV.    Thyroid gland
       a. Butterfly shaped endocrine gland overlying larynx
       b. Produces iodine containing hormones (T3 and T4 which regulate
          metabolic rates)
       c. Produces polypeptide hormone: calcitonin (lower serum calcium leves)
       d. Structure of thyroid gland
               i. 2 lobes connected by an isthmus
              ii. Pyramidal lobe often noted as a small superior projection
             iii. Extensive vascular supply and venous drainage
       e. Arterial Supply
               i. Via 2 arteries (3 in 10%)
                      1. superior thyroid – generally the 1st branch of the external
                          carotid
                      2. inferior thyroid – large branch of the thyrocervical trunk
                      3. Thyroid ima artery – in approximately 10% of people and
                          arises from the brachiocephalic trunk/aorta
       f. Venous Drainage
               i. 3 pairs of veins drain thyroid
                      1. Superior thyroid veins – drain into the IJV
                      2. Middle thyroid veins – drain into the IJV
                      3. Inferior thyroid veins – generally drain into the left
                          brachiocephalic vein
                                        Superior thyroid artery



                                                                               Superior thyroid veins


Internal jugular veins




                                                                             Middle thyroid artery




                                                Inferior thyroid veins
           Inferior thyroid artery



           V.    Parathyroid Glands
                 a. 4 parathyroid glands (superior and inferior) located on the posterior
                    surface of the thyroid
                 b. Difficult to locate in the cadaver
                 c. Sometimes found on the thymus gland
                 d. Develop from the 3rd and 4th pharyngeal pouches
                 e. Secrete parathormone (controls phosphorous and calcium levels)


           VI.   Nerves in the Deep Neck
                 a. Phrenic (C3-C5) – descends on the anterior aspect of the anterior scalene
                 b. Vagus Nerve (CN X) – courses thru the neck within the carotid sheath
                    then enters the thorax
                         i. Vagus gives rise to 2 laryngeal branches in neck
                                1. Superior laryngeal nerves – divides into 2 branches
                                       a. Internal branches – enter the larynx and innervate
                                           the mucous membranes above the vocal cords
                       b. External branches – simply innervate a muscle of
                           the larynx  the cricothyroid muscle
                2. Recurrent laryngeal nerves (right and left) – both loop
                   around or “recur” @ different levels as they travel toward
                   the larynx
                       a. Right recurrent laryngeal – nerve loops around
                           the right subclavian artery
                       b. Left recurrent laryngeal – nerve loops around the
                           aortic arch
                       c. Both recurrents then innervate the mucous
                           membranes within the larynx below the vocal cords
                           and the remaining muscles of the larynx
                       d. Recurrents ascend in the “tracheoesophageal
                           groove”
                       e. Explored in Head and Neck 8


                                          Internal branch




External branch




                                               Cricothyroid
                                               muscle


 esophagus                  Recurrent laryngeal nerve

 c. Sympathetic trunk – posterior to carotid sheath  has 3 main ganglia
        i. Superior
       ii. Middle
      iii. Inferior
      iv. Ganglia receive preganglionic sympathetic fibers from spinal cord
       v. Majority of these sympathetics synapse with superior cervical
           ganglion and then travel to their target via blood vessels (internal
           and external carotid arteries)
VII.    Splenius Muscles (capitis and cervicus)
        a. Superficial intrinsic back muscle located in cervical region
        b. These splenii muscles cover underlying region known as “suboccipital
           triangle”

VIII.   Suboccipital triangle
        a. Triangular area inferior to the occipital bone
        b. Muscular borders
                i. Rectus Capitus Posterior Major
               ii. Obliquus Capitus Inferior
              iii. Obliquus Capitus Superior
              iv. Primarily postural muscles – proprioceptive monitors of head
                   position
               v. All innervated by the suboccipital nerve
        c. Contains
                i. Vertebral artery
               ii. Suboccipital nerve  dorsal ramus of C1 spinal nerve
              iii. Also 2 other associated nerves
                        1. Greater occipital nerve – dorsal ramus of 2nd cervical
                           nerve  cutaneous innervation posterior head
                        2. Least occipital nerve – dorsal ramus of 3rd cervical nerve –
                           cutaneous posterior neck and head

IX.     Cutaneous Innervation to the Head and Neck
        a. Sensory branches of the cervical plexus (ventral rami C2,3,4) provide
           cutaneous innervation of the anterior and lateral neck
        b. Dorsal rami of cervical nerves (greater and least occipital) provide
           cutaneous innervation to the posterior neck and scalp
        c. Facial Region later…




                          ?                               Dorsal
                                                          rami



                                           ?
                            ?

                                     Cervical plexus
                                     (ventral rami)
BOTTOM LINE CONCEPTS:

   Branches of the subclavian artery can be remembered with the helpful
    mnemonic VIT C & D

   Anterior and middle scalene muscles provide protection and passage for the
    roots of the brachial plexus & the subclavian artery as they travel toward the
    upper extremity

   Anterior scalene muscle divides the subclavian artery into three divisions

   Thyroid gland receives vascular supply from both the external carotid & the
    thyrocervical trunk

   Sympathetic trunk is located posterior to the carotid sheath
Head and Neck 3: FACE AND PAROTID GLAND

  I.    Face
        a. Shape of the face is determined by:
               i. Shape of bones
              ii. Amount and distribution of subcutaneous tissue (fat/fascia)
             iii. Facial musculature

  II.   Facial Osteology
        a. Anterior Aspect of skull
                 i. Frontal bone – forms the skeleton of the forehead and the roof of
                    the orbit
                ii. Nasal bones – form the bridges of the nose
               iii. Maxillae – surround the piriform aperture and form the floor of
                    orbit
               iv. Zygomatic bones – form lateral wall of orbit and cheek bones
                v. Mandible – lower jaw
                        1. body
                        2. ramus
                        3. mental protuberance – triangular elevation that forms
                            prominence of the chin




                                     Frontal bone
           Supraorbital
           notch
                                                                         Zygomatic


         Infraorbital
         foramen
                              ramus
                                                                   Maxillae

         Mental                      body
         foramen
                                                            Mental protuberance
b. Major foramina of the facial region (for i-iii see above diagram)
       i. Supraorbital notch (foramen) – passage for supraorbital nerve
          and vessels
      ii. Infraorbital foramen – passage for the infraorbital nerve and
          vessels
     iii. Mental foramen – for passage of mental nerve and vessels
     iv. Stylomastoid foramen – located between the styloid and mastoid
          processes – for passage of the facial nerve (CN VII) out of the base
          of the skull




   Styloid process




     Stylomastoid
     foramen
           c. Lateral Aspect of the Skull
                   i. Parietal bone
                  ii. Frontal bone
                iii. Occipital bone
                 iv. Temporal bone
                  v. Sphenoid bone
                 vi. Mandible
                vii. Zygomatic bone
               viii. Maxillae
                 ix. Lacrimal bone
                  x. Nasal bone




                                                          Pterion




                                   1
                                                      2



                                       5
                                                  4
            10                                                      3
                               7

                          8
                 9

                                       6




ITC: Fractures of the Calvaria
   - Pterion (above) represents a region on the lateral skull where the frontal, parietal,
       sphenoid, and temporal bones articulate
   - Coursing just beneath this pterion runs the middle meningeal artery
   - This artery can be lacerated following trauma to the pterion resulting in epidural
       hematoma
III.   Muscles of Facial Expression
       a. Develop in association with 2nd pharyngeal arch
       b. Hence – all innervated by Facial Nerve (CN VII)
       c. Muscles located in the superficial fascia
       d. Originate from either bone or fascia and insert in skin
       e. Convey emotions  understanding is clinically relevant
       f. Divided into 4 groups
              i. Orbital group
                     1. Orbicularis oculi
                             a. Consists of 2 mucscles
                                     i. Orbital – close eyes tightly
                                    ii. Palpebral – blink
                             b. closes the eyelids and protects the eye
                             c. Facial nerve innervated (CN VII)
                     2. Corrugator supercilli
                             a. Draws eyebrows together as in frowning
                             b. Causes vertical wrinkling b/w above the nose
                             c. Facial nerve innervation (CN VII)
             ii. Nasal group
                     1. Nasalis – “flare the nostrils”
                     2. Depressor Septi – pulls nose inferiorly
                     3. Procerus – pulls medial eyebrow inferiorly – as one
                         attempts to reduce the glare of sunlight
            iii. Oral group
                     1. Mentalis – protrudes the lower lip
                     2. Depressor anguli oris – depresses the corner of the mouth
                         (frowning)
                     3. Depressor labii inferioris – draws lower lip inferiorly
                         (sadness)
                     4. Orbicularis oris
                             a. Sphincter muscle
                             b. Compresses and protrudes the lips – purses lips
                                when kissing or whistling)
                             c. Facial nerve innervated (CN VII)
                     5. Buccinator
                             a. Presses cheek against the teeth – aids in chewing by
                                keeping food between teeth
                             b. Also used to expel air while playing a musical
                                instrument (wind)
                             c. Duct of parotid gland pierces this muscle as it enters
                                oral cavity
                             d. Facial nerve innervated (CN VII)
                     6. Zygomaticus major – laughing or smiling
                     7. Levator labii superioris alaeque nasi – raises the upper
                         lip
                                  8. Risorius – draws corner of the mouth laterally as in
                                     “grinning”
                           iv. “Other muscles” group
                                  1. Frontalis
                                         a. Actually part of a larger muscle  “epicranius
                                            muscle”
                                         b. Wrinkles the forehead and produces the expression
                                            of surprise
                                         c. Facial nerve innervated (CN VII)
                                  2. Occipitalis
                                  3. Auricular muscles – wiggle the ears
                                  4. Platysma
                                                                               Levator labii
              Frontalis                                                        alaeque nasi


                                                                               Zygomaticus major
         Procerus

                                                                                   Auricular muscles
      Corrugator
      supercilli

                                                                                          Occipitalis

      Nasalis

Orbicularis
oris

                                                                                     Buccinator
    Orbicularis
    oculi
 Mentalis
                                                                               Risorius


      Depressor
      septi                                   Platysma

    Depressor labii
    inferioris

                Depressor anguli
 IV.      Vasculature of the Face
          a. Arteries
                 i. 2 major sources: Branches from these arteries perfuse the tissues of
                    the facial region and anastomose with one another
                         1. External Carotid Artery
                                 a. Facial artery
                                         i. Crosses the inferior border of the mandible –
                                            can palpate pulse
                                        ii. Quite large and rather tortuous course
                                       iii. Numerous branches
                                               1. Inferior labial
                                               2. Superior labial
                                               3. Lateral nasal
                                               4. Terminates as the angular artery as
                                                    it course toward the medial corner of
                                                    the eye (canthus)
                                 b. Superficial temporal
                                         i. Transverse facial
                         2. Internal Carotid Artery
                                 a. Opthalmic artery
                                         i. Supraorbital artery
                                        ii. Supratrochlear artery


                                           Supratrochlear
       Superficial temporal




                                                                               Supraorbital
         Transverse
         facial



   Angular


Superior labial


               Inferior labial


                                           Facial artery
b. Veins
       i. Facial vein
             1. provides majority of venous drainage of the face
             2. courses diagonally across the face with facial artery
             3. drains into the internal jugular vein (IJV)
             4. Veins in the head and facial region have NO VALVES 
                  blood can flow either direction (face turns red)
             5. Artery = tortuous Vein = straight
      ii. Other venous drainage
             1. facial vein has numerous connections with venous channels
                  passing into deeper regions of head
                      a. ophthalmic vein and infraorbital vein
                      b. deep facial vein and pterygoid vein
             2. all these channels have interconnections with “intercranial
                  veins and sinus” (ie. Cavernous)
             3. infection in the facial region can travel into cranial cavity
                  via these interconnections




                                                                   IJV
V.   Parotid Gland
     a. Largest of salivary glands
     b. Enclosed in a tough fascial sheath – continuation of the investing layer of
        deep cervical fascia (remember….invests both trapezius and SCM)
     c. Drains via the parotid duct – passes superficial to masseter muscle then
        pierces the buccinator and enters the oral cavity
     d. Parasympathetic innervation provided by the Glossopharyngeal Nerve
        (CN IX)
     e. Many important structures pass through the parotid gland
             i. Facial Nerve – exits skull via the stylomastoid foramen and
                divides into terminal branches
                    1. Temporal
                    2. Zygomatic
                    3. Buccal
                    4. Mandibular
                    5. Cervical
                    6. Remember: To Zanzibar By Motor Car
                    7. These branches innervate muscles of facial expression




                                              1




                                                    2




                                              3

                                                    4
      Stylomastoid
      foramen
                                          5
              ITC: Injury to Facial Nerve
                 - Injury to the facial nerve results in paralysis of some or all of the muscles of facial
                     expression on the affected side
                 - Due to the superficial position of these branches, the are subject to injury
                 - facial nerve palsy can have many causes (traumatic) or be idiopathic  referred
                     to as Bell’s Palsy
                         o most common age for Bell’s palsy is between 30 and 60
                         o most people, seems to be a short term thing  recover nerve function
                         o some people don’t recover and suffer recurring problems
                                  saliva drips out when eating
                                  speech affected
                                  eye cannot close  cornea dries

                                 ii. Retromandibular vein
                                        1. formed by union of maxillary vein and superficial
                                           temporal vein
                                        2. exits inferior aspect of parotid gland and commonly divides
                                           into 2 branches
                                               a. anterior branch – joins the facial vein (to IJV)
                                               b. posterior branch – joins the external jugular vein
                                                   (EJV)
                                iii. External Carotid
                                        1. Divides into its terminal branches
                                               a. Maxillary
                                               b. Superficial temporal arteries




                                                                                                       Superficial
                                                                                                       temporal




Posterior
Retromandibular

                                  Facial vein

External jugular vein                                                External carotid artery
                           Anterior Retromandibular
VI.   Lymphatic Drainage of the Head and Neck
      a. As in other parts of body, we have 2 sets of lymph nodes in the head and
         neck
             i. Superficial cervical nodes – form a “ring” around the head and
                basically drain lymph from the face and scalp
                    1. Occipital nodes
                    2. Mastoid nodes
                    3. Parotid nodes
                    4. Submandibular nodes
                    5. Submental nodes
                    6. REMEMBER: Only Medically Paranoid Students Suffer
                    7. These nodes eventually drain into deep cervical nodes
            ii. Deep cervical nodes
                    1. eventually receive all lymphatic drainage from the head and
                        neck
                    2. 2 sets of deep cervical nodes on right and left
                            a. Right – drain along IJV to right lymphatic duct
                            b. Left – drain along IJV to the thoracic duct




                                                               1

                                                        2




                                        3
                              4

                5
                                                      Deep cervical
                                                      nodes
CRANIAL NERVES – SEE OUTLINE OF NERVOUS SYSTEM 4 – CRANIAL
NERVE OVERVIEW

  VII.   Continuation of Cranial Nerve Examination
         a. Trigeminal Nerve (CN V) – great sensory nerve of the face
                 i. Has numerous sensory branches that convey sensory stimuli (pain,
                    touch, temperature) from the facial region to CNS
                ii. Large sensory ganglion resides in the cranial cavity – trigeminal
                    ganglion
                        1. trigeminal ganglion houses the cell bodies of sensory
                            neurons of trigeminal nerve (like DRG)
               iii. 3 main divisions of Trigeminal nerve (CN V)
                        1. Ophthalmic Division (V1)
                               a. Conveys general sensory information
                               b. Exits skull via superior orbital fissure
                               c. Important branches
                                        i. Supraorbital nerve
                        2. Maxillary Division (V2)
                               a. Conveys general sensory information
                               b. Exits skull via foramen rotundum
                               c. Important branches
                                        i. Infraorbital nerve
                        3. Mandibular Division (V3)
                               a. Conveys both general sensory and branchial
                                   motor (to the muscles of mastication)
                               b. Exits via foramen ovale
                               c. Important branches
                                        i. Mental nerve
                                       ii. Auriculotemporal nerve
                        4. REMEMBER: THESE ARE ALL GENERAL
                            SENSORY NERVES


               iv. Trigeminal Dermatomes
                       1. Ophthalmic Division (V1) – provides sensation between
                          the eyes and forehead (frontal bone region)
                       2. Maxillary Division (V2) – provides sensation between the
                          eyes and mouth (maxillary bone region)
                       3. Mandibular Division (V3) – provides sensation to the
                          mandibular region  also innervates mastication muscles

                v. Motor innervation from Trigeminal nerve
                     1. to muscles associated with the 1st pharyngeal arch 
                          referred to as muscles of mastication
                              a. Masseter
                              b. Temporalis
                      c.   Pterygoids
                      d.   Mylohyoid
                      e.   Anterior digastric
                      f.   Tensor veli palatine
                      g.   Tensor tympani
                      h.   f and g are not muscles of mastication, but are
                           associated with 1st pharyngeal arch and innervated
                           by Mandibular division V3

b. Facial Nerve (CN VII)
        i. Facial nerve has 3 functions
              1. Innervates all muscles that are associated with the 2nd
                   pharyngeal arch  essentially the muscles of facial
                   expression (branchial motor nerves)
              2. Conveys taste sensation from the anterior 2/3 of the
                   tongue (special sensory nerves)
              3. Conveys parasympathetic (visceral motor nerves) to the
                      a. Lacrimal glands
                      b. Nasal glands
                      c. Sublingual glands
                      d. Submandibular glands
       ii. Facial nerve exits the brainstem as a large motor root and a
           smaller root referred to as the intermediate nerve
     iii. Both roots enter the internal acoustic meatus in the temporal
           bone  where they join
      iv. Within the temporal bone, the facial nerve gives rise to 3 major
           branches
              1. Greater petrosal nerve
                      a. Parasympathetic (visceral motor) fibers to the
                           pterygopalatine ganglion  where they synapse
                           and travel to the larimal gland (eye) and the glands
                           of the nasal cavity/palate

               2. Nerve to stapedius
                     a. Innervates a small muscle (stapedius) of the
                         middle ear that is associated with the 2nd
                         pharyngeal arch
                     b. Stapedius muscle helps dampen (reduce) loud
                         sounds to reduce damage to the inner ear
                     c. Nerve to stapedius carries branchial motor fibers
               3. Chorda tympani nerve
                     a. Taste fibers
                             i. Courses thru the middle ear cavity and then
                                joins a branch of the trigeminal nerve
                                (lingual nerve) to get to the tongue
                                     ii. Carries taste (special sensory) to the
                                         anterior 2/3 of the tongue
                                    iii. Cell bodies of these taste fibers reside in a
                                         small sensory ganglion within the temporal
                                         bone  geniculate ganglion
                              b. Parasympathetics
                                      i. also conveys parasympathetics to the
                                         submandibular and sublingual gland
                                     ii. visceral motor fibers synapse in the
                                         submandibular ganglion located in the oral
                                         cavity and are then distributed to the
                                         salivary glands
                                    iii. finally exit via the stylomastoid formaen
                                         and enter the parotid gland where it divides
                                         into its terminal motor branches to
                                         innervated muscles of facial expression
                                             1. Temporal, Zygomatic, Buccal,
                                                  Mandibular, Cervical

BOTTOM LINE CONCEPTS:

   Trigeminal nerve has 3 divisions: V1, V2 & V3 that all carry general sensation
    (pain, touch, temp) from the facial region into the CNS
   V3 of trigeminal also innervates all muscles associated with the 1st arch…
    essentially the muscles of mastication
   Numerous structures pass through the substance of the parotid gland including the
    facial nerve
   Facial nerve branches (To Zanzibar By Motor Car) innervates the muscles of
    facial expression
   Facial nerve provides parasympathetic innervation to the lacrimal, nasal, and
    salivary glands
   Facial nerve also conveys special sensory information (taste) from the anterior
    tongue

				
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