Lecture 9.1: Submandibular gland + Oral Cavity floor

Question 1

What are anterior and posterior boundaries of the oral cavity

Answer 1

Opens anteriorly to the oral fissure,

Posteriorly to the oropharyngeal isthmus.

Question 2

What muscles form the floor of the oral cavity and what attachments do they have (from inferior to superior)

Answer 2

1. Paired mylohyoid muscle connected midline by the raphe
   (mylohyoid line to hyoid bone)
2. the paired geniohyoid muscles
   (inferior mental spine->hyoid bone)

3) Extrinsic tongue muscles: (one attachment in tongue)

a) Genioglossus: from superior mental spine and hyoid bone
b) Hyoglossus: from hyoid

c) Styloglossus: from styloid process
d) Palatoglossus: from palate

4) Intrinsic muscles of tongue: both insertions in the tongue (static):
- Inferior longitudinal, Transverse, Vertical and Superior Longitudinal

Question 3

What are the two potential surgical spaces in the floor of the oral cavity and what are their contents

Answer 3

1st space: between mylohyoid and hyoglossus muscle:

• CN12 (hypoglossal) runs lower than
• Lingual nerve (CNV3) and Chorda tympani (CN7) running together
• Deep part of the Submandibular gland and duct.
• deep lingual vein

2nd space: between hyoglossus and genioglossus.

• Lingual artery
• CN9 (glossopharyngeal)
• Dorsal lingual vein

Question 4

What would be the signs of damage to first surgical space

Answer 4

1st surgical space

• CN12: Loss of extrinsic and intrinsic tongue muscles except palatoglossus
• Lingual nerve (CNV3): Loss of general sensation from ant 2/3 tongue
• Chorda tympani (CN7): loss of taste from ant 2/3 tongue
• Deep part of the Submandibular gland and duct damage
• ( deep lingual vein damage )

Question 5

What would be the signs of damage to second surgical space

Answer 5

• Lingual artery: loss of blood supply to the tongue - pulsatile bleeding
• CN9: loss of taste and general sensation of posterior 1/3 of tongue
• (Dorsal lingual vein damage)

Question 6

What is the general structure and position of the submandibular gland and its duct

Answer 6

The submandibular glands are hook shaped with the larger arm = superficial part (palpable outside of oral cavity) and

shorter arm = deep part which loops around the posterior margin of mylohyoid muscle.

The submandibular duct originates from superficial part but emerges from medial side of deep part, passing forward to open on the sublingual caruncle (papilla) beside base of frenulum of tongue.

Question 7

In order to remove the submandibular gland, what tissue layers must be dissected

What are the neurovascular and muscles at risk at each step?

Superficial -> deep

Answer 7

1. Skin
2. Subcutaneous fat
3. Platysma
   - must check for marginal mandibular nerve (cn7) 3cm below margin of mandible
   also crosses the facial artery and vein.
4. Investing layer of deep cervical fascia

5.Anterior/ Post belly of digastric
(if anterior there might be nerve to mylohyoid lying in between them)
6. Superficial submandibular gland around
7. Mylohyoid muscle

8. Deep part of submandibular gland in 1st potential space:

• lingual nerve (also chorda tympani) hooked around the submandibular duct- have to separate +
• hypoglossal nerve at risk

Here the hyoglossus muscles is the posterior boundary: don’t cut.

Question 8

What are the 3 structures running across the submandibular gland

Answer 8

facial artery, vein, lymph nodes

Question 9

What is the course of the lingual nerve from the submandibular gland- need to be separated from the what on removal of the gland

Answer 9

Lingual nerve enters superiorly to the deep portion of the submandibular gland (inside the mandible) and loops under the duct from lat to med deep to mylohyoid on the surface of hyoglossus- so needs to be separated upon removal

Question 10

How does the texture of the tongue change from front to back

Answer 10

Goes from smooth to rough due to 3 different papillae:

Fungiform, filiform and vallate

Question 11

What is the lateral wall of the oral cavity and its function

Answer 11

Cheeks made of Fascia + Buccinator muscle (CN7) sandwiched between skin and oral mucosa.

It holds the cheeks against the alveolar arches and keeps food between the teeth when chewing.

Question 12

What two muscles provide continuity between walls of the oral and pharyngeal cavities

Answer 12

Buccinator and Superior constrictor muscle of the pharynx as they are in the same plane