Oral Cavity, Tongue and Pharynx
Dissection:
  Tongue and Submandibular Region:
  1. Examine the surface of the tongue.  Locate the sulcus terminalis, a v-shaped furrow that divides the tongue into an anterior 2/3 and a posterior 1/3.  Identify the circumvallate papilli that line the sulcus and the foramen cecum at the pit of the apex.  Understand the embryological significance of the foramen.
  2. Identify, on the underside of the tongue, the opening to the duct of the submandibular salivary gland (the sublingual caruncle).  Also notice the sublingual fold which contains the openings of the sublingual salivary gland.
  3. Make an incision down the lateral border of the tongue inferior to the papilli that cover the superior surface.  Peel down the mucosa across the floor of the mouth to an area just inferior to the mylohyoid line of the mandible.
  4.  Running along the lateral, inferior border of the tongue are two structures that must be identified. The submandibular salivary duct runs posterior to anterior and the lingual nerve runs superior-posterior to anterior-inferior.  At the posterior of the tongue, the duct is laterally positioned to the medially placed lingual nerve.  The nerve crosses under the duct from lateral to medial entering the tongue and the duct continues anteriorly to the oral cavity (laterally to the nerve).
  5. Clean the lingual nerve back toward the infratemporal fossa and identify the submandibular ganglion.
  6. Clean the floor of the oral cavity, beneath the tongue and note the mylohyoid muscle running from the mandible to the mylohyoid raphe.  Also the geniohyoid muscle runs from the hyoid bone to the bulk of the tongue superior to mylohyoid.  CN XII (Hypoglossal) should be visible running between mylohyoid and geniohyoid.  This nerve enters the tongue to supply motor innervation to the intrinsic muscles of the tongue (In sagittal section, identify the genioglossus, geniohyoid and mylohyoid muscles and their arrangement along the floor of the oral cavity).
  7. Between CN XII and the lingual nerve, the lingual artery should be present as the main arterial supply to the tongue.

Images


Dissection:
  Oral Cavity:
  1. Identify the following landmarks in the oral cavity: the maxillary and mandibular teeth, the opening of the parotid duct, the frenuli, the uvula, hard and soft palate, and the “Pillars of the Fauces”
  2. Remove the mucosa from the hard palate.  Beneath this mucosa is a layer of palatine glands which should be dissected to locate the greater and lesser palatine nerves.  The greater palatine nerve exits the greater palatine foramen, located medial to the maxillary third molar, and runs in an anterior direction as sensory to the hard palate.  The lesser palatine nerve exits the lesser palatine foramena, medial and posterior to the maxillary third molar, and runs in a posterior direction as sensory to the soft palate.
  3. Locate the incisive foramen just posterior to the maxillary incisors where the nasopalatine nerve communicates with the greater palatine nerve from the nasal to the oral cavity.
  4. Remove the mucosa from the soft palate.  Locate the palatine aponeurosis which is a tendinous sheath into which the muscles of the soft palate insert.
  5. Identify the muscles that create the “Pillars of the Fauces”.  Anteriorly, the palatoglossus muscle, posteriorly the palatopharyngeus muscle.  The pharyngeal tonsil should sit between these muscles.  Whether the tonsil is present, or not, there should be an artery and vein plexus serving this region.
  6. Locate the tendon of the tensor veli palatini muscle.  The muscle’s origin is the scaphoid fossa at the base of the medial pterygoid plate.  Its tendon loops around the hamulus of the medial pterygoid plate and inserts into the palatine aponeurosis

Pictorial Atlas:
Landmarks
Salivary Glands
Hard Palate
Nerves
Floor
Soft Palate
Autonomics


Dissection:
  Pharynx:
  1. Beginning in the nasopharynx, locate the following surface landmarks: the opening of the auditory (Eustachian) tube, the torus tubarius, the salpingopharyngeal fold, the fold of the levator veli palatini, and the pharyngeal recess.
  2. Remove the mucoperiosteum of the nasopharynx.  Identify the levator veli palatini which emerges from the inferior edge of the cartilaginous auditory tube and inserts on the soft palate aponeurosis.  Also identify the salpingopharyngeus muscle which extends from the inferior border of the torus tubarius to the lateral pharyngeal wall.
  3. There are three pharyngeal constrictor muscles; superior, middle and inferior.  Locate and identify these muscles on both the interior and exterior surface of the pharynx.  The muscles sit like stacked cups inside each other creating a continuous muscle.
  4. Understand the spaces created by the three pharyngeal constrictors and the structures that pass through each space:
       skull-superior constrictor – auditory tube and the soft palate muscles
       superior-middle constrictors – stylopharyngeus muscle, and CN IX (Glossopharyngeal)
       middle-inferior constrictors – thyrohyoid membrane and internal laryngeal nerve

Fascia Planes and Spaces
Images