The Head and Neck, Pharynx,
and Oral Cavity
Neck Regions
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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.
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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.
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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.
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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.
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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
thyrohyoid
sternocleidomastoid
trapezius
clavicle
1. Digastric
2. Mylohyoid
3. Geniohyoid
4. Sternohyoid
5. Sternomastoid
6. Clavotrapezius
7.
External Jugular
Vein
Cadaver
Specimen of
Lateral Neck
Regions of the Neck
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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
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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
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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
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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.
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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
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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.
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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.
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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.
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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.
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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
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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.
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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
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2. NASOPHARYNX
-located superior and posterior to
the soft palate.
-contains the PHARYNGEAL
TONSILS and TUBAL TONSILS
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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.
2.
3.
4.
5.
Mouth
Left and right nasal passages
Eustachian tubes (connect middle ear
to the throat)
Larynx
Esophagus
Swallowing
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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
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Very similar to bone.
Three major components:
1. hydroxyapatite Ca (PO ) (OH)
2. bone collagen
3. cells
5
4
3
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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
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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
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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
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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.
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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.
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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.
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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.
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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.
Masseter
muscle
Parotid Duct
Parotid gland
Submandibular gland
Sublingual gland
Submandibular Duct
1.
Masseter Muscle
2.
Parotid Gland
3.
Parotid Duct
4.
Submandibular
Gland
5.
Sublingual Gland
6.
Lymph Nodes
7.
Molar Gland