Oral Cavity, Oral Pharynx and Palatine Tonsil

Palpable structures in the vestibule of the oral cavity

The vestibule of the mouth is the space between the lips and the teeth. If you start in the mid line along the bottom, you can feel the inferior frenulum. Move your finger to the side until it moves up along a ridge, this is the anterior border of the ramus of the mandible. While your finger is on this border, bite down and you will feel the masseter muscle contracting. If you move your finger as far up as you can go, you will feel the coronoid process of the ramus and the tendinous insertion of the temporalis muscle. Now move your finger in the upper recess of the vestibule until you come to the mid line again and you will feel the upper frenulum. Look in your own mouth for the opening of the parotid duct that enters the vestibule opposite the 2nd upper molar tooth.

Oral Cavity Proper

Structures that you should be able to feel or see in your own mouth.

Figure 1.

    First, the boundaries of the mouth are:

  • superior--hard and soft palates
  • inferior--tongue and floor of mouth
  • anterolateral--upper and lower teeth
  • posterior--palatoglossal fold (5)
Structures to identify:
  1. vestibule
  2. hard palate
  3. soft palate
  4. uvula
  5. palatoglossal arch
  6. palatine tonsil
  7. palatopharyngeal arch
  8. posterior wall of oropharynx
  9. pterygoid hamulus
Figure 2. Tongue elevated.
  1. frenulum of tongue
  2. ridge formed by deep lingual vein
  3. sublingual fold
  4. sublingual caruncle
  5. opening of submandibular duct
The sublingual gland forms the sublingual fold and sends multiple small ducts into the mouth along the fold.

Figure 1


Figure 2

Surface of the tongue viewed from above.
Note the tip of tongue, epiglottis and soft palate with the uvula as points of reference!

Identify:

  1. anterior 2/3rd of tongue
  2. posterior 1/3rd of tongue
  3. palatogossal fold
  4. palatine tonsil
  5. fungiform papillae
  6. circumvallate papillae
  7. sulcus terminalis
  8. foramen cecum
  9. foliate papillae
Innervation:
Anterior 2/3rd:
  • general sensation--lingual nerve (V3)
  • taste--chorda tympani (VII)
Posterior 1/3rd:
  • general sensation--glossopharyngeal (IX)
  • taste--glossopharyngeal (IX)

Floor of the Mouth

Here is a perfect example of how important it is to orient yourself. In order to show the structures in the floor of the mouth, the tongue must be reflected posteriorly (notice the vertebral column). I always look for the mandible for anterior orientation.
    In opening up the floor of the mouth, the mucous membrane is gently incised just above the sublingual gland and the fascia covering the gland (sg) is pulled posteriorly along with the tongue. This reveals:
  • mylohyoid muscle (floor)
  • geniohyoid muscle just above the mylohyoid
The mylohyoid muscles of the two sides joint in the mid line forming a sling across the floor of the mouth. In the section of the head and neck, the mylohyoid muscle can be seen in cross section.
Note where the tip of the tongue is
It has been displaced posteriorly.

Removal of the fascia around the sublingual gland (slg) and the deep part of the submandibular gland (sm) allows you to visualize the remainder of the structures of the mouth.

  • styloglossus muscle (sg)
  • hyoglossus muscle (hg)
  • genioglossus muscle (gg)
  • submandibular duct (5)
  • lingual nerve (1)
  • submandibular ganglion (2)
  • hypoglossal nerve (3)
  • C1 nerve to geniohyoid (4)
You can also see the genioglossus muscle from the sectioned tongue.

 
Muscle
Origin
Insertion
Action
Nerve Supply
styloglossus styloid process merges with hyoglossus and genioglossus muscles in the tongue draws tongue up and back to aid swallowing food XII
hyoglossus greater horn of hyoid bone merges with styloglossus and genioglossus muscles draws side of tongue down XII
genioglossus genial tubercle of mandible fans out in the tongue to make up the bulk of the tongue pulls tongue forward, sticking the tongue out XII
intrinsic muscles tissues of tongue tissues of tongue produce small changes in the contour of the surface of tongue XII
mylohyoid mylohyoid line of mandible hyoid bone and raphe elevates hyoid bone and floor of mouth to aid in swallowing nerve to mylohyoid (V3)
geniohyoid lower genial tubercle of mandible body of hyoid bone elevate hyoid bone or depress mandible C1

 
You will now identify the structures found in the lateral wall of the oropharynx. This is where the palatine tonsil is located. Again, orient yourself: identify the tongue, hard palate, hyoid bone and soft palate.
Identify the palatoglossal arch and the palatopharyngeal arch. Find the palatine tonsil between the two arches, if it is present. Beneath the mucosa of the arches, identify the small palatoglossus (pg) and palatopharyngeus (pp) muscles. You might also see the superior pharyngeal constrictor (SC) and middle pharyngeal constrictor (mc) at this stage.
When the tonsil is removed, you can see the structures that make up the tonsillar bed and that could be injured during a tonsilectomy.
  • superior pharyngeal constrictor (SC)
  • pterygomandibular raphe (PR)
  • middle pharyngeal constrictor (MC)
  • tonsillar branch of facial artery (1)
  • glossopharyngeal nerve (2)
  • stylohyoid ligament (3)
You might also be able to see the buccinator muscle (BUC) in this dissection. The pterygomandibular raphe serves as an insertion point for two muscles: superior constrictor and buccinator.

List of Items Covered in this Lesson

Bones

mandible
genial tubercles
mylohyoid line
maxilla
palatine process
palatine
horizontal process
hyoid
lesser horn
greater horn
medial pterygoid plate
pterygoid hamulus

Muscles

styloglossus
hyoglossus
genioglossus
mylohyoid
geniohyoid
palatoglossus
palatopharyngeus

Arteries

lingual
tonsilar branch of facial

Nerves

glossopharyngeal
hypoglossal
lingual
submandibular ganglion
C1 fibers

Tongue

sulcus terminalis
foramen cecum
fungiform papillae
foliate papillae
circumvallate papillae
frenulum
sublingual fold
anterior 2/3rd
posterior 1/3rd
sublingual caruncle
opening of submandibular duct

Tonsil region

palatoglossal fold
palatopharyngeal fold
palatine tonsil
superior pharyngeal constrictor
pterygomandibular raphe
stylohyoid ligament
glossopharyngeal nerve
tonsilar branch of facial artery
 

Nasal Cavity & Paranasal Sinuses   Larynx


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