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The Head and Neck

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The Head and Neck Powered By Docstoc
					The Head and Neck, Pharynx,
      and Oral Cavity
Neck Regions
   When dissecting the neck from the
    anterior surface, you will come across
    the HYOID BONE.
   The hyoid bone is the only bone in the
    body that does not articulate with other
    bones.
   The base of the tongue is attached to the
    hyoid bone.
   The hyoid bone is attached by muscles to the
    skull, providing for flexibility for speech.
   It also attaches to the styloid process of the
    TEMPORAL BONE.
   The muscles in the neck are named for their
    points of attachment.
   From the STERNUM to the THYROID
    CARTILAGE lies the STERNOTHYROID
    MUSCLE. This muscle lies lateral and
    deep to the STERNOHYOID MUSCLE.
   From the STERNUM to the MASTOID
    PROCESS lies the STERNOMASTOID
    MUSCLE.
   From the CLAVICLE to the MASTOID
    PROCESS lies the CLEIDOMASTOID
    MUSCLE.
   In humans, the STERNOMASTOID and
    the CLEIDOMASTOID are one muscle
    called the STERNOCLEIDOMASTOID
    MUSCLE.
   The DIGASTRIC MUSCLE opens the jaw
    and attaches to the mastoid process
    and the inner border of the mandible at
    the central portion (midline fusion
    area).
        stylohyoid
                     digastric
                                 sternohyoid

                                      omohyoid


                                 sternocleidomastoid
thyrohyoid




                                    trapezius




                                      clavicle
1. Digastric

2. Mylohyoid

3. Geniohyoid

4. Sternohyoid

5. Sternomastoid

6. Clavotrapezius

     External Jugular
7.
     Vein
  Cadaver
Specimen of
Lateral Neck
Regions of the Neck
   Anterior Triangle
      -bounded by sternohyoid muscle, the
    digastric muscle, and the sternomastoid
    muscle.
   Posterior Triangle
      - bounded by the cleidomastoid
    muscle, the clavotrapezius muscle, and
    the clavicle.
Anterior Triangle
   Thyroid Gland
     -bilobate
     -endocrine gland
   Common Carotid Arteries and Branches
     - cranial thyroid artery
     - muscular branch (lateral to the CTA)
     - cranial laryngeal artery
     - lingual artery (sublingual artery)
     - internal (brain) and external carotid arteries
    (passes deep to the digastric muscle
   INTERNAL JUGULAR VEIN runs with the
    common carotid artery in the anterior
    triangle.
   The HYPOGLOSSAL NERVE (cranial nerve XII)
    runs with the sublingual artery.
   The SPINAL ACCESSORY NERVE (cranial
    nerve XI) innervates the cleidomastoid and
    trapezius muscles.
   The nerve that runs with the common carotid
    artery is the VAGUS NERVE (cranial nerve X)
    which is joined by the SYMPATHETIC TRUNK.
Posterior Triangle
   The EXTERNAL JUGULAR VEIN runs
    obliquely across this triangle.
   The SPINAL ACCESSORY NERVE runs
    from the cleidomastoid and
    clavotrapezius. This nerve is the only
    structure found in both triangles.
   The SUBCLAVIAN ARTERY and VEIN are
    found deep to the clavicle.
   Deep to the clavicle you will find the
    BRACHIAL PLEXUS. This complex of
    nerves are VENTRAL RAMI from
    C5-T1. It innervates the muscles and
    provides sensation to the upper
    extremity.
            Muscles of the
            Posterior Neck


Identify the Following:


Splenius capitis
Rhomboid major
Rhomboid minor
Supraspinal ligament
Trapezius
Semispinalis capitis
Splenius cervicis
Sternocleidomastoid
         The Larynx and Thyroid Gland
   The LARYNX
    (voice box) is a
    modified portion
    of the trachea.
   It is superior to
    the trachea.
   There are
    cartilaginous
    rings that are
    connected by
    dense connective
    tissue forming a
    tube.
   The TYROID CARTILAGE is shaped like a
    shield when viewed from the anterior surface.
    This is the ADAM’S APPLE. This is not a
    complete ring.
   On the posterior side of the thyroid cartilage,
    the CRICOID CARTILAGE extends superiorly
    to where the thyroid cartilage would be. This
    cartilage is sometimes called the SIGNET
    RING CARTILAGE.
   It has a narrow band across the
    anterior side.
   It is superficial to the thyroid cartilage
    posteriorly where it is connected by the
    CRICOTHYROID LIGAMENT (dense
    connective tissue).
   Inferiorly, the cricoid is attached to the
    first ring to the trachea by dense CT.
   The EPIGLOTTIS is a spade shade cartilage
    that is important during swallowing.
   It tips inferiorly to seal off the glottis and
    prevents food from entering the trachea.
   The ARYTENOID CARTILAGE is below the
    epiglottis at the entrance to the GLOTTIS.
   The GLOTTIS is a passageway into the
    trachea. The thyroid cartilage forms the
    walls of the glottis. The arytenoid cartilage
    extends inferiorly into the glottis.
   The arytenoid cartilages anchor the vocal cords.
   The true vocal cords are located inferiorly inside the
    glottis.
   As air passes over the vocal cords they flutter,
    producing sound from the vibration.
   Pitch can be changed by tightening or loosening the
    cords.
   In humans, the tongue is used to make sense of the
    sounds (make words). You cannot talk if your
    tongue is not functioning.
   There are folds covering part of the epiglottis called
    FALSE VOCAL CORDS.
Pharynx and Oral Cavity
   Superior to the ORAL CAVITY is the
    HARD PALATE composed of the
    MAXILLARY and PALATINE bones.
   Superior and posterior to the oral cavity
    are the INTERNAL NARES.
   From the internal nares, if we go
    anteriorly we will find the EXTERNAL
    NARES or NOSTRILS.
   Posterior to the hard palate is the SOFT
    PALATE. This is muscular tissue that is
    moved during swallowing.
   Hanging from the soft palate is a conical
    structure called the UVULA.
   The two nasal cavities are separated by the
    NASAL SEPTUM which is formed by the union
    of the VOMER and PERPENDICULAR PLATE of
    the ETHMOID bones.
3 Areas of the Oral Cavity
1.   OROPHARYNX
       -soft palate to epiglottis
       -two sets of TONSILS
           a. Palatine
           b. Lingual
         -the tonsils remove pathogens that
     enter the pharynx. They contain
     lymphocytes
   2. NASOPHARYNX
        -located superior and posterior to
    the soft palate.
        -contains the PHARYNGEAL
    TONSILS and TUBAL TONSILS
   3. LARYNGOPHARYNX
        -inferior to the epiglottis and
    posterior to the larynx.
        - this division opens into the
    esophagus and larynx.
Sagital section of cadaver
head


Notice the nasal conchae.
They serve to expand the
surface area to warm and
moisten breathed air.


Also, notice the position of
the spinal cord within the
vertebral canal.
                     Epiglottis


                Hyoid Bone

             Thyrohyoid Ligament
                       Thyroid
                       Cartilage


                     Aryetnoid
                     cartilage

                      Cricoid
                      cartilage



ANTERIOR   trachea



                Tracheal rings
                                   POSTERIOR
5 Openings into the Pharynx
1.   Mouth
2.   Left and right nasal passages
3.   Eustachian tubes (connect middle ear
     to the throat)
4.   Larynx
5.   Esophagus
Swallowing
   Is a reflex.
   When the mouth closes, the soft palate is pushed
    superiorly and closes the nasal passages
   A sphincter valve closes off the eustachian tubes
   The glottis closes and respiration stops. The glottis
    also bends and closes the entrance into the larynx.
   The esophagus is opened by pressure of the food.
    This allows the epiglottis to open.
   Food then enters the esophagus.
Teeth
   Very similar to bone.
   Three major components:
     1. hydroxyapatite Ca (PO ) (OH)
                         5   4   3


     2. bone collagen
     3. cells
   The pH of the mouth is usually 7.2
   There are acids in the mouth that come
    from three sources:
        1. stomach acid during vomiting
        2. foods
        3. waste products of mouth
    bacteria
    Types of Teeth
   INCISORS – chisel shaped for nipping
    food.
   CANINES – cone shaped for tearing
   PREMOLARS –
   MOLARS -              grinding food

   32 teeth in the Permanent Dentition
   20 teeth in the Deciduous Dentition
Tooth Anatomy
   Enamel: hardest substance in the body
   Pulp Cavity: contains arteries, veins, and
    nerves.
   Alveolus: made of alveolar bone
   Root: made of dentin
   Gingiva: gum
   Periodontal membrane: periosteum found
    around the tooth
   Cementum: material that holds the tooth in
    the alveolus.
Identify the
Following:




      Incisors
      Molar
      Premolars
      Canines
Salivary Glands
   When you dissect your cat, you will
    notice two muscles on the inside of the
    cheek.
   The DIGASTRIC MUSCLE opens the
    jaw.
   The MASSETER MUSCLE closes the jaw.
   The masseter inserts on the mandible.
   Superficial to part of the masseter and
    anterior to the ear is the large PAROTID
    GLAND. This gland produces SALIVARY
    AMYLASE (ptyalin), a digestive enzyme.
   The parotid gland is GRANULAR, it is
    attached by fascia. It is also the largest
    of the salivary glands.
   The parotid empties into the PAROTID DUCT
    which empties between the last two molars at
    the angle of the jaw.
   The parotid gland is an EXOCRINE GLAND.
    Exocrine glands empty via a duct to a specific
    location. The other type of gland is an
    ENDOCRINE GLAND that empties directly into
    the bloodstream.
   Caudal and ventral to the parotid gland
    is the SUBMANDIBULAR GLAND
    (SUBMAXILLARY).
   The SUBMAXILLARY DUCT empties this
    gland. It runs on the lateral aspect of
    the digastric muscle.
   This gland carries saliva into the angle
    of the lower jaw.
   The SUBLINGUAL GLAND is on the
    submaxillary duct. It is wedge shaped and it
    is lateral to the digastric muscle.
   The DORSAL and VENTRAL FACIAL NERVES
    run around the outline of the masseter
    muscle. These nerves come out in front of
    the ear from the STYLOMASTOID FORAMEN
    and branch across the face.
                          Parotid Duct
          Masseter
          muscle




                                                Parotid gland




                                          Submandibular gland




Sublingual gland
                     Submandibular Duct
1.   Masseter Muscle

2.   Parotid Gland

3.   Parotid Duct

     Submandibular
4.
     Gland

5.   Sublingual Gland

6.   Lymph Nodes

7.   Molar Gland

				
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posted:10/6/2011
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