Dissector Answers - Upper GI Tract

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Describe the hard and soft palate.
  2. Describe the location of the parotid salivary gland.
  3. Identify three main neurovascular structures that traverse the parotid gland.
  4. Identify the branches of the facial nerve in the face.
  5. Identify some exemplary muscles of facial expression acting on the oral opening.
  6. Identify the masticatory muscles and give their functions.
  7. Define the boundaries and contents of the infratemporal fossa.
  8. Identify the branches of the trigeminal nerve and their functions related to mastication and sensation from the face.
  9. Identify the chorda tympani nerve and give its function.
  10. Describe the structure and function of the temporomandibular joint.
  11. Identify the muscles bordering the submandibular and paralingual spaces.
  12. List and identify the major nerves and vessels of the submandibular and paralingual spaces.
  13. Describe the submandibular and sublingual salivary glands and give their innervations.
  14. Describe the muscles of the tongue.
  15. Describe the oral cavity, its oral vestibule and dental arches (including temporary and permanent dentitions).
  16. Review the carotid sheath and contents.
  17. Identify, trace and describe the general functions of cranial nerves IX (glossopharyngeal), X (vagus), XI (spinal accessory), XII (hypoglossal).
  18. Describe the pharynx, its anatomical architecture and action of its musculature during swallowing.

Learning Objectives and Explanations:

1. Describe the hard and soft palate. (N63, N64A, N64B, TG7-23, TG7-24)
The hard palate is formed primarily by the palatine processes of the maxillary bones, with the horizontal processes of the palatine bones forming the posterior third. The soft palate stretches posteriorly. It is a fibromuscular septum that can be moved to close off the nasopharynx. Its muscles are the levator veli palatini, tensor veli palatini, and musculus uvulae.
2. Describe the location of the parotid salivary gland. (N4, N25, TG7-30A, TG7-30B, TG7-31A)

The parotid gland extends into the parotid fossa, anteroinferior to the external acoustic meatus, wedged between the ramus of the mandible and the mastoid process. The apex of the parotid gland is posterior to the angle of the mandible, and its base is related to the zygomatic arch.

3. Identify three main neuromuscular structures that traverse the parotid gland. (N25, N69, N70, TG7-19, TG7-31)

From superficial to deep, the structures traversing the gland are arranged: facial nerve and its branches, retromandibular vein, and external carotid artery. Retromandibular vein is formed by the union of the superficial temporal and maxillary veins. It divides into anterior and posterior divisions and drains the sides of the head, scalp, and deep face.

4. Identify the branches of the facial nerve in the face. (N25, N123, TG7-87)

Branches of the facial nerve include: temporal, zygomatic, buccal, marginal mandibular and cervical. The temporal branch of the facial nerve emerges from the superior border of the parotid gland and crosses the zygomatic arch. The zygomatic branches pass via two or three branches to the eye to innervate the inferior part of the orbicularis oculi and other facial muscles inferior to the orbit. Buccal branches pass external to the buccinator to innervate this muscle and muscles of the upper lip. The (marginal) mandibular branch innervates the muscles of the lower lip and chin. It emerges from the inferior border of the parotid gland and crosses the inferior border of the mandible deep to the platysma to reach the face. The cervical branch passes from the inferior border of the parotid gland to the mandible to innervate the platysma.

5. Identify some exemplary muscles of facial expression acting on the oral opening. (N26, N54, N69, N123, TG7-29, TG7-30, TG7-31, TG7-87)

Zygomaticus major, levator labii superioris, depressor labii inferioris, levator anguli oris, depressor anguli oris, orbicularis oris, and buccinator are all innervated by the facial nerve (CN VII) and supplied by the facial artery. Zygomaticus major arises from the upper lateral surface of the zygomatic bone to insert into the skin of the upper lip. It elevates and draws the corner of mouth laterally. Levator labii superioris originates from the inferior margin of the orbit to insert on the skin of upper lip. It elevates the upper lip. Levator anguli oris attaches superiorly to the infraorbital margin and inferiorly to the angle of the mouth. Depressor anguli oris depresses the angle of the mouth. Posterior fibers of the platysma assist with this movement. Depressor labii inferioris, lateral to the mentalis, attaches inferiorly to the mandible and merges superiorly with its contralateral partner and the orbicularis oris and draws the lip inferiorly and slightly laterally. Orbicularis oris originates from the skin and fascia of the lips and inserts in the skin and fascia of the lips. It purses the lips. The buccinator runs from the mandible to the angle of the mouth and lateral portion of the lips. It pulls the corner of the mouth laterally. It is important to note that although this muscle lies fairly deeply in the face, it is still innervated by the facial nerve, not the trigeminal nerve (which penetrates buccinator with branches of the buccal NERVE, a sensory nerve, as opposed to buccal BRANCHES of facial nerve, that are motor).

6. Identify the masticatory muscles and give their functions. (N54A, N54B, N55, N69, N46, TG7-31, TG7-34, TG7-85)
Masseter muscle
Origin: Zygomatic arch
Insertion: Lower half of the mandibular ramus
Blood supply: Masseteric artery
Nerve supply: Masseteric nerve
Action: Mandibular elevation (powerful crusher of food)
Temporalis muscle
Origin: Temporal fossa, temporal fascia
Insertion: Coronoid process and temporal crest of the mandibular ramus
Blood supply: Anterior and posterior deep temporal arteries
Nerve supply: Anterior and posterior deep temporal nerves
Action: Elevation and retraction of the mandible
Medial pterygoid
Origin: Medial surface of lateral pterygoid plate
Insertion: Medial surface of the ramus of the mandible (below mandibular foramen)
Blood supply: Arterial twigs of the maxillary artery
Nerve supply: Nerve to medial pterygoid
Action: Protraction and elevation of the mandible
Lateral pterygoid
Origin: Upper head - base of the skull (greater wing of sphenoid); Lower head - lateral surface of lateral pterygoid plate
Insertion: Upper head - capsule and articular disc of the TMJ; Lower head - pterygoid fovea of the condylar neck
Blood supply: Twigs from the maxillary artery
Nerve supply: Short nerves from the mandibular division of the trigeminal nerve
Action: Protraction and opening movements of mandible
7. Define the boundaries and contents of the infratemporal fossa. (N4, N54A, N54B, ,N55, TG7-04A, TG7-32A, TG7-32B)
Boundaries:
Medial: Lateral pterygoid plate.
Lateral: Medial surface of the ramus of the mandible.
Anterior: Tuberosity of the maxilla.
Posterior: Deep part of the Parotid region.
Superior: Base of the skull (greater wing of sphenoid bone)
Inferior: Medial pterygoid muscle.
Contents:
Medial pterygoid muscle
Lateral pterygoid muscle
Maxillary artery and vein
Pterygoid plexus of veins
Mandibular division of trigeminal nerve
Otic ganglion
8. Identify the branches of the trigeminal nerve and their functions related to mastication and sensation from the face. (N45, N46, N122, TG7-29, TG7-81C, TG7-81D, TG7-85)
V1: Ophthalmic division
General sensory from the cornea, skin of forehead, scalp, eyelids, nose, and mucosa of nasal cavity and paranasal sinuses

V2: Maxillary division
General sensory from the skin of the face over the maxilla, including upper lip, maxillary teeth, mucosa of nose, maxillary sinuses, and palate

V3: Mandibular division (major nerve supply to masticatory muscles)
Sensory branches: Motor Nerves (to all masticatory muscles):
9. Identify the chorda tympani nerve and give its function. (N46, N123, TG7-37, TG7-84, TG7-88B)
Chorda tympani is a branch of the facial (CN VII) nerve that carries taste fibers from the anterior two-thirds of the tongue and joins the lingual nerve in the infratemporal fossa. In addition, the chorda tympani carries preganglionic parasympathetic fibers (secretomotor fibers) for the submandibular and sublingual salivary glands.
10. Describe the structure and function of the temporomandibular joint. (N14, TG7-32B, TG7-32C, TG7-33)
The TMJ is both a hinge and gliding synovial joint, with an articular disc present between the mandibular condyle and both the mandibular fossa and articular eminence on the temporal bone. With the fibrous capsule attaching to the perimeter of the articular surfaces and the edges of the articular disc, two articular cavities are formed. The upper one is between the articular disc and temporal bone, while the lower one is between the disc and mandibular condyle. The lateral and medial TM ligaments limit the posterior movements of the mandible. Movements involved include: hinge movement at the lower joint and gliding at the upper joint. The joint is innervated by the auriculotemporal nerve.
11. Identify the muscles bordering the submandibular and paralingual spaces. (N27, N28, N46, N53A, N53C, N59, N63, TG7-12, TG7-37A, TG7-37B, TG7-38)
MUSCLEORIGININSERTIONACTIONINNERVATIONNOTES
Digastric muscle, anterior belly digastric fossa of mandible body of hyoid via a fibrous loop over an intermediate tendon elevates and draws forward hyoid bone; depresses mandible mylohyoid nerve [from inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve (CN V3)] forms anterior boundary of submandibular triangle
Digastric muscle, posterior belly mastoid notch of temporal bone body of hyoid via a fibrous loop over an intermediate tendon elevates and retracts the hyoid bone; depresses mandible facial nerve (CN VII) forms posterior boundary of submandibular triangle
Stylohyoid posterior side of the styloid process splits around intermediate tendon of digastric to insert on the body of the hyoid bone elevates and retracts the hyoid bone facial nerve (CN VII) medial and parallel to posterior belly of digastric in submandibular triangle
Mylohyoid mylohyoid line of mandible midline raphe and body of the hyoid bone elevates the hyoid bone and tongue; depresses the mandible mylohyoid nerve [from inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve (CN V3)] paired mylohyoid muscles form the muscular floor of oral cavity
Geniohyoid mental spines of mandible body of hyoid bone elevates hyoid; depresses mandible C1 ventral ramus via fibers carried by hypoglossal nerve (i.e., ansa cervicalis fibers) adjacent to the midline and superior to mylohyoid
12. List and identify the major nerves and vessels of the submandibular and paralingual spaces. (N46, N59, N122, N123, N126, N69, N70, TG7-18, TG7-19, TG7-40B, TG7-40C, TG7-81, TG7-84, TG7-94)
NERVE SOURCE BRANCHES MOTOR SENSORY NOTES
to mylohyoid inferior alveolar (from mandibular division of trigeminal, V3) none to mylohyoid m., terminates in anterior belly of digastric m. none arises near lingula of mandible (and often grooves the medial surface of the ramus)
lingual n. mandibular division of trigeminal, V3 none none general sensation to anterior two-thirds of tongue forms hammock for submandibular duct by crossing it twice in paralingual space
submandibular ganglion preganglionic parasympathetic from chorda tympani n. postganglionic parasympathetic to submandibular and sublingual glands secretomotor to submandibular and sublingual glands none hangs off lingual nerve just above deep part submandibular gland in the paralingual space
chorda tympani facial (CN VII) none secretomotor to submandibular and sublingual glands taste to anterior two-thirds of tongue indistinguishable from lingual nerve in submandibular and paralingual spaces
hypoglossal n. (CN XII) hypoglossal nucleus of medulla in brain none intrinsic and extrinsic muscles of tongue none only motor nerve to tongue


ARTERY SOURCE BRANCHES SUPPLY NOTES
facial external carotid a. ascending palatine a., tonsilar br., submental a., superior and inferior labial as., lat. nasal br., angular a. lower part of palatine tonsil, submandibular gland, facial muscles, & fascia deep to submandibular gland
submental facial a. none sublingual gland, submental triangle none
lingual external carotid a. suprahyoid br., dorsal lingual brs., deep lingual a., sublingual a. tongue, suprahyoid muscles, palatine tonsil runs deep to hyoglossus m.
deep lingual lingual a. none anterior tongue terminal branch of lingual a. from bifurcation deep to hyoglossus m.
sublingual lingual a. none sublingual gland, mylohyoid m. mucous membranes of floor of mouth terminal branch of lingual a. from bifurcation deep to hyoglossus m.


VEIN TRIBUTARIES DRAINS INTO REGION DRAINED NOTES
facial vein submental vein, others common trunk for lingual, facial, retromandibular vs., then internal jugular submandibular gland and others superficial to submandibular gland
submental vein none facial v. submandibular triangle anterior to submandibular gland, including sublingual gland
vena comitans of the hypoglossal n. deep lingual v., sublingual v. lingual v. tongue, sublingual region accompanies CN XII, usually inferior to n., runs on hyoglossus m.
13. Describe the submandibular and sublingual salivary glands and give their innervations. (N46, N61, N123, N133, TG7-31, TG7-37, TG7-40, TG7-84)
Submandibular gland: This salivary gland occupies most of the posterior part of the submandibular triangle. The superficial portion is larger and lies inferior to the mylohyoid muscle directly underneath the superficial layer of cervical fascia. The deep portion folds around the posterior edge of the mylohyoid muscle to lie deep in the sublingual space between the mylohyoid and hyoglossus muscles. The 5 cm long submandibular duct arises from the deep part of this gland and passes forward and medialward to open in the sublingual caruncle at the side of the lingual frenulum. The facial artery and vein supply this gland, and lymphatic drainage is to the submandibular lymph nodes.

Innervation of submandibular gland:
Sublingual gland: This is the smallest salivary gland. It is located beneath the oral mucosa in the floor of the mouth between the mandible on one side and the genioglossus and hyoglossus muscles on the other side. The sublingual gland sits on the mylohyoid muscle. Unlike the submandibular gland, which drains via one large duct, the sublingual gland drains via approximately 12 small ducts along the sublingual fold along the floor of the mouth. (This occurs basically in a line behind the sublingual caruncle.) Blood supply is from the sublingual branch of the lingual artery and from the submental branch of the facial artery.

Innervation of the sublingual gland: Same as the submandibular gland.
14. Describe the muscles of the tongue. (N53A, N53C, N59, N63, N68, N126, TG7-40, TG7-38)
MUSCLEORIGININSERTIONACTIONINNERVATIONNOTES
Hyoglossus body and greater horn of the hyoid bone intrinsic muscles of the tongue depresses side of tongue; retracts tongue hypoglossal nerve (CN XII) this extrinsic muscle of the tongue lies in submandibular triangle
Genioglossus mental spine on inner aspect of mental symphysis fans out to insert into the tongue from tip to base inferior fibers protrude tongue; middle fibers depress tongue; superior fibers draw tip back and down hypoglossal nerve (CN XII) this extrinsic muscle of the tongue is fan shaped and lies vertically next to the median plane
Styloglossus styloid process side of the tongue retracts and elevates tongue hypoglossal nerve (CN XII) this extrinsic muscle runs longitudinally along the side of the tongue
Superior longitudinal base of tongue apex of tongue hypoglossal nerve (CN XII) intrinsic muscle immediately under mucous membrane of dorsum
Inferior longitudinal base of tongue apex of tongue hypoglossal nerve (CN XII) intrinsic muscle runs between genioglossus and hyoglossus on inferior surface of tongue
Transverse lingual septum of tongue submucous tissue at side of tongue compresses sides of tongue; shapes tongue for speech and mastication hypoglossal nerve (CN XII) intrinsic muscle runs transversely between superior and inferior longitudinal layers
Vertical superior surface of tongue inferior surface of tongue shapes tongue for speech and mastication hypoglossal nerve (CN XII) intrinsic muscle with fibers at border of tongue
15. Describe the oral cavity, its oral vestibule, and the dental arches (including temporary and permanent dentitions). (N56, N57A, N57B, N63, TG7-38, TG7-32)
The oral cavity extends from the lips to the palatopharyngeal folds. The oral vestibule lies between the lips and the teeth.

The dental arches, upper and lower, are made, on each side, of 2 incisors, 1 canine, 2 premolars, and 3 molar teeth for the permanent dentition, and 2 incisors, 1 canine, and 2 molars for the temporary or deciduous dentition.
16. Review the carotid sheath and contents. (WB 201,203,206; N 32, 33, 35, 125, 126, TG 7-17, 7-18, 7-13, 7-10)
The carotid sheath is a tube-shaped fascia wrapping the common carotid a., internal carotid a., internal jugular v., and vagus n. It lies anterolateral to the cervical sympathetic trunk, behind the sternocleidomastoid muscle. The sheath blends with the thyroid fascia anteromedially and with the deep surface of sternocleidomastoid anterolaterally. Posteriorly it is attached to prevertebral fascia along the tips of the transverse processes of vertebrae. It ends at the base of the skull where it attaches around the jugular foramen and carotid canal. It is here at the base of the skull that the internal carotid artery and internal jugular vein go their separate ways. Inferiorly, the carotid sheath fuses with scalene fascia, adventitia of great vessels, and the fibrous pericardium.

Within the sheath, artery is medial, vein lateral, and nerve posterior and between the vessels.

The superior root of ansa cervicalis (from cervical plexus C1-2) lies draped over the anterior part of the carotid sheath.

The carotid sinus is the dilated terminal part of the common carotid artery, approx. 1 cm long. It is a baroreceptor in the elastic wall which responds to changes in blood pressure. The carotid sinus is innervated by a branch of the glossopharyngeal nerve.

The carotid body is an disc-shaped mass lying behind the bifurcation of the common carotid artery. It has a chemoreceptor sensitive to blood oxygen concentration. The carotid body is innervated by the nerve to carotid sinus from glossopharyngeal nerve, and also receives the nerve to carotid body, a branch of the vagus n. (CN X), as well as sympathetic fibers.
17. Identify, trace and describe the general functions of cranial nerves IX (glossopharyngeal), X (vagus), XI (spinal accessory), XII (hypoglossal). (WB 91,205,206,218,239; N 118, N125, 127, 128, TG 7-90, 7-91, 7-93, 7-94)
IOlfactorySomeSensory
IIOpticSaySensory
IIIOculomotorMoneyMotor
IVTrochlearMattersMotor
VTrigeminalButBoth
VIAbducensMyMotor
VIIFacialBrotherBoth
VIIIVestibulocochlearSaysSensory
IXGlossopharyngealBigBoth
XVagusBrainsBoth
XIAccessoryMatterMotor
XIIHypoglossalMostMotor


Glossopharyngeal, CN IX, Both motor and sensory.
Emerges from medulla in the groove dorsal/lateral to the olive, passes through jugular foramen, passes along the posterior border of stylopharyngeus m.

The short story:
  • Motor: innvervates stylopharyngeus m. (that's the only muscle it innervates)
  • Sensory: posterior 1/3 of tongue: general sensory (pain, etc) and special sensory (taste); sensory to oropharynx via pharyngeal plexus
The long story . . . Branches include:
  • Tympanic n. - parasympathetic fibers to otic ganglion, which supplies parotid gland (increases salivation) and mucous membrane of the middle ear
  • Carotid sinus nerve, with branches to carotid sinus and carotid body
  • Pharyngeal branches which form the pharyngeal plexus (along with vagus and cervical sympathetics)
  • Branches to stylopharyngeus (the ONLY motor branches of this nerve)
  • Branches to tonsils
  • Lingual branches - afferent fibers from the tongue report taste sensations and somatic sensations from the posterior third of the tongue
Vagus, X, Both motor and sensory.
Arises from the medulla, in the groove dorsal and lateral to the olive, in the same plane as glossopharyngeal (CN IX) and accessory (CN XI). The vagus leaves the skull through the jugular foramen, descends through the neck in the carotid sheath behind and between the internal carotid/common carotid and the internal jugular v.

The short story:
  • Vagus supplies all the muscles of the pharynx and soft palate and upper 2/3rds of esophagus EXCEPT stylopharyngeus (from glossopharyngeal) and tensor veli palatini (from mandibular division of trigeminal V3). It does this primarily through the pharyngeal plexus. The inferior pharyngeal constrictor is innervated by the superior laryngeal external branch.
  • Vagus, through the superior and inferior laryngeal nerves, also supplies all muscles and sensory innervation of the larynx and laryngopharynx.
  • Motor: The inferior laryngeals (=recurrent laryngeals) supply all the muscles of the larynx EXCEPT cricothyroideus. Superior laryngeal external branch supplies cricothyroideus.
  • Sensory: The inferior laryngeals supply sensory fibers to the larynx below the vocal folds, but their role is minor in sensation. Superior laryngeal internal branch supplies sensory fibers to the larynx above the vocal folds. It is the principal sensory nerve of the larynx, according to W+B.
  • It also supplies fibers to the dura, trachea, heart, etc
The long story...
Branches include:
  • meningeal to posterior dura mater
  • auricular to back of external ear
  • pharyngeal, which contribute to the pharyngeal plexus. The pharyngeal plexus (from vagus, glossopharyngeal, and cervical symp trunk) supplies the constrictor muscles
  • superior laryngeal n. Arises from the inferior ganglion of the vagus. Passes inferomedially toward the larynx. Has 2 branches.
    • internal branch: sensory to the mucous membrane of epiglottis
    • external branch: inferior pharyngeal constrictor m., cricothyroid m.
  • cervical cardiac
  • recurrent laryngeal
    • right recurrent laryngeal loops under and behind the subclavian a.
    • left recurrent laryngeal loops under aortic arch
    • both recurrent laryngeals ascend between the esophagus and trachea and enter the larynx from under the inferior constrictor muscle. Above the cricothyroid articulation, name changes to inferior laryngeal n.
    • branches of the laryngeals include: cardiac, tracheal, esophageal, pharyngeal branch to inferior pharyngeal constrictor m.
    • inferior laryngeals innervate all intrinsic muscles of the larynx EXCEPT cricothyroideus
Accessory, CN XI, Motor nerve.
Arises from rootlets of C1-C5 which ascend within the vertebral column through foramen magnum. It then descends through the jugular foramen, where it receives fibers from the cranial portion of the accessory nerve. Upon leaving through the jugular foramen, the accessory nerve lies between the internal carotid and internal jugular veins. It travels laterally, piercing and innervating sternocleidomastoid. It then passes through the muscle, goes dorsally under the superficial layer of deep cervical fascia to trapezius, where it joins sensory branches of C3 and C4 to form the subtrapezial plexus.
Hypoglossal, CN XII, Motor nerve.
Motor nerve of the tongue arises from the medulla oblongata in the anterolateral sulcus between the pyramid and the olive. The rootlets which form the hypoglossal unite in the hypoglossal canal. It emerges from the canal medial to carotid sheath, then goes lateral. Travels for a short distance with the superior root of ansa cervicalis. Turns forward near angle of the mandible, loops around occipital artery, enters the submandibular triangle deep to posterior belly of digastric, and goes superior to the greater horn of the hyoid bone. Terminal branches distribute to styloglossus, hyoglossus, genioglossus, and intrinsic muscles of the tongue. Carries C1 and C2 fibers that leave as the superior root of ansa cervicalis, and the nerves to the thyrohyoid and geniohyoid muscles.
18. Describe the pharynx, its anatomical architecture and action of its musculature during swallowing. (WB 235; N 35, 63, 65, 66, 67, N125, 126, 130, TG 7-10A, 7-10B, 7-20, 7-21, 7-22, 7-24)
The pharynx is the multi-purpose chamber that connects the nasal and oral cavities superiorly with the esophagus and larynx inferiorly. It is multi-purpose in that it is the common pipe for food, liquids, and air, and it is the job of the pharynx to see that these invaluable items travel through the right pipe to the proper destination.

The pharynx is the part of the digestive system posterior to the nasal and oral cavities, extending posteriorly and inferiorly past the larynx. It extends to the inferior border of the cricoid anteriorly and the inferior border of C6 posteriorly. The posterior wall of the pharynx lies against the prevertebral layer of deep cervical fascia.

In the pharynx the paths of food and air cross. Food travels from the mouth (anterior) to the esophagus (posterior). Air travels from the choanae (posterior) to the trachea (anterior).

The interior of the pharynx is divided into 3 parts: Structure of the pharynx:
The wall of the pharynx is composed of two layers of 3 muscles each. The external rings of circular constrictor muscles - the superior, middle, and inferior constrictors - contract serially to push a bolus down to the esophagus. The internal ring of longitudinal muscles - palatopharyngeus, stylopharyngeus, and salpingopharyngeus - elevate and widen the pharynx to accommodate a bolus during swallowing. The fascia covering the outside of the posterior of the pharynx is the buccopharyngeal fascia. The interior fascia is the pharyngobasilar fascia.
Innervation of the pharynx:
Motor:
Pharynx muscles are innervated by branches from pharyngeal plexus with 2 exceptions: stylopharyngeus (glossopharyngeal, CN IX) and tensor veli palatini (supplied by mandibular division of trigeminal, V3). Other than these two exceptions, the vagus is the source of motor innervation to the pharynx. The inferior pharyngeal constrictor also receives innervation from the recurrent laryngeal and external branch of the superior laryngeal (which are also derived from the vagus).

Sensory:
The glossopharyngeal sensory contribution to the pharyngeal plexus is connected to the mucosa of all three parts of the pharynx. (Sensory nerve supply to the nasopharynx is primarily from the maxillary division of trigeminal, V2)
The stages of swallowing (deglutition) (W+B 238)

Questions and Answers:

19. What is the primary function of the tensor veli palatini? (N68, N69, N72, TG7-24, TG7-65)
The most important function of tensor veli palatini is to open the auditory tube by pulling its lateral wall inferiorly. This flushes the middle ear cavity with fresh air, thereby equalizing pressure within the middle ear.
20. Can you find the deep temporal nerves and arteries? (N46, N69, TG7-34, TG7-85)
They should be present innervating and feeding the temporalis muscle, respectively. The anterior and posterior deep temporal arteries are branches of the maxillary artery, and their accompanying nerves are branches of mandibular division of trigeminal.
21. What is the articular eminence? (N14, TG7-06)
The articular eminence is a projection of bone at the anterior margin of the mandibular fossa.
22. Consider the condylar movements at each (joint cavity formed by the articular capsule). (N14, TG7-33)
See above, but briefly:
Hinge movement at the lower joint (initiation of mandibular opening)
Gliding at the upper joint (termination of mandibular opening).
23. What kind(s) of fibers does it (chorda tympani) carry? (N46, N123, TG7-84)
See above, objective 4.
24. Identify other branches of the mandibular division of the trigeminal, a mixed motor and sensory nerve. (N46, TG7-84A, TG7-84B, TG7-84C, TG7-85A, TG7-85B)
See above, objective 3.
25. Accompanying autonomic fibers? Otic ganglion? (N46, N125, TG7-84)
The autonomic fibers from the chorda tympani were mentioned above (objective 4). Other fibers present involve the otic ganglion. Specifically, this structure is a parasympathetic ganglion just below the foramen ovale, which receives preganglionic parasympathetic fibers from the glossopharyngeal nerve (CN IX) via the lesser petrosal nerve. Postganglionic parasympathetic fibers emerging from the ganglion join the auriculotemporal nerve and reach the parotid gland.
26. Define the boundaries of the submandibular triangle. (N28, TG7-02, TG7-12)
The submandibular triangle is defined by the inferior border of mandible and the anterior and posterior bellies of digastric muscle. Please note that the submandibular triangle is the "suprahyoid portion of the anterior cervical triangle" (W&B 213)
27. Trace the facial artery and vein noting relations with the submandibular gland (which one is superficial or deep to the gland?). (N69, N70, TG7-19)
The facial artery is deep to the superficial portion of the submandibular gland. The facial vein crosses the superficial surface of the submandibular gland
28. Can you find the mylohyoid nerve? (N46, TG7-85)
The mylohyoid nerve arises from the inferior alveolar nerve, which is in turn a branch of the mandibular division of the trigeminal nerve (CN V3). It arises near the lingula of the mandible. The inferior alveolar nerve continues its course through the mandibular foramen, but the mylohyoid nerve stays on the medial surface of the mandible. This makes the nerve readily identifiable, as it is plastered to the inside of the mandible.
29. Locate the mylohyoid nerve (what muscles does it supply; what does it arise from?) (N46, TG7-85)
The mylohyoid nerve supplies the mylohyoid muscle before burying itself in the anterior belly of the digastric muscle.
30. On the tongue, identify the foramen cecum (significance?). (N58, TG7-39)
The foramen cecum is a small pit on the dorsum of the tongue located in the midline. It is at the apex of the sulcus terminalis. It is an embryological remnant marking the site of the diverticulum of the thyroid gland, the thyroglossal duct.
31. Where is the lingual tonsil? (N58, N63, TG7-39)
The lingual tonsil is in the submucosa on the superior surface of the root of the tongue just behind the sulcus terminalis. It is a collection of lymphoid nodules that give the posterior one-third of the tongue its warty appearance.
32. Consider the motor and sensory (special and general) innervation of the tongue. (N62, N126, TG7-39, TG7-90, TG7-94)
GENERAL SENSATIONTASTE (SPECIAL SENSATION)MOTOR
ANTERIOR TWO-THIRDSLingual n. (V) Chorda tympani (VII) Hypoglossal n. (XII) -- extrinsic and intrinsic muscles
POSTERIOR ONE-THIRDGlossopharyngeal n. (IX) Glossopharyngeal n. (IX) (includes vallate papillae)
EPIGLOTTIC REGION OF TONGUE Superior laryngeal n. (X) Superior laryngeal n. (X), internal branch
33. Read about the intrinsic muscles of the tongue. (N126, TG7-38)
These are all muscles with attachments entirely within the tongue. Like all true tongue muscles (intrinsic and extrinsic), they are innervated by the hypoglossal n. (CN XII). They are the superior longitudinal muscle, the inferior longitudinal muscle, the transverse lingual muscle, and the vertical muscle. All are treated in more detail in the objectives section (but the only thing that I think we need to be aware of according to the laboratory manual is that intrinsic muscles, as a group, exist).
34. Consider actions of both intrinsic and extrinsic groups of muscles in moving the tongue and changing the shape of the organ. (N53A, N53C, N59, N63, N68, N126, TG7-38, TG7-40)
The actions of the extrinsic muscles are covered in the objectives section. In addition, the palatoglossus, which is not a true tongue muscle, assists in elevation of the tongue. The intrinsic muscles assist in all of the actions of the tongue but are particularly involved in deviations of the tongue from side to side. Note that extrinsic and intrinsic muscles combine for all of the actions of the tongue. "In eating, the tongue forms itself into a trough-like receptacle, conducts the food between the teeth for their tearing and crushing actions, and prevents food from falling to the floor of the mouth. Finally it makes firm pressure against the palate above and forces the mixed food and saliva into the oropharynx" (W&B 276).
35. Identify the ascending pharyngeal artery (a branch of the external carotid) distributing to the dorsal wall of the pharynx. Do you find any lymph nodes (retropharyngeal)?
Retropharyngeal lymph nodes are usually present in the tissue between visceral and musculoskeletal parts of the neck, known as the retropharyngeal space, but difficult to find unless they are enlarged by disease. They are associated with the deep cervical nodes found in the carotid sheath just lateral to the space. (N 73, 136, TG 7-74)
36. Observe the pharyngobasilar fascia forming the pharyngeal wall above the superior pharyngeal constrictor. What tissue is it?
The wall of digestive and respiratory tracts, of which the pharynx is common to both, consists of a mucosal lining, a connective tissue layer - the submucosa - and a muscular wall. The pharyngobasilar fascia is the submucosa of the pharyngeal wall. (N 67, TG 7-21)
37. Clear the stylopharyngeus muscle and trace to the pharynx. Between what two muscles does it pass?
The stylopharyngeus muscle passes between the superior and middle pharyngeal constrictors. (N 67, TG 7-21)
38. Consider the complete blood supply to pharyngeal constrictors. Innervation?
The pharynx is supplied by the ascending pharyngeal artery, branches of the facial, maxillary and inferior thyroid. The pharynx receives nerves from the pharyngeal plexus which is composed of branches of the glossopharyngeal nerve (sensory), the vagus (motor and parasympathetic motor to the glands of the mucosa) and the sympathetic trunk (vasomotor to the blood vessels of the pharynx). (N 69, 75, 125, 126, 130, 131, 136, TG 7-22, 7-21, 7-20, 7-23, 7-24)
39. Define nasal, oral and laryngeal portions of pharynx. What boundaries separate these regions?
The nasopharynx extends from the choanae anteriorly to the soft palate inferiorly; it is the respiratory portion of the pharynx. The oropharynx extends from the soft palate above to the epiglottis below and opens into the mouth anteriorly. The laryngopharynx extends from the epiglottis to the beginning of the esophagus below. It opens into the larynx anteriorly.
40. What structures lie immediately deep (lateral) to the palatine tonsil? Where is the lingual tonsil?
The superior pharyngeal constrictor muscle lies lateral to the palatine tonsil, along with the vessels supplying the tonsil. The lingual tonsil is in the submucosa on the superior surface of the root of the tongue just behind the sulcus terminalis. It is a large collection of lymphoid nodules that give the posterior one-third of the tongue its warty appearance.