Oral Cavity, Pharynx and Oesophagus SDL notes

Question 1

What causes depression of the jaw at the TMJ?

Answer 1

Depression of the jaw is by gravity, or the actions of the suprahyoid musicles.

To open the jaw widely, the mandible is protruded by the lateral pterygoid particularly, and also the medial pterygoid and masseter.

Question 2

What muscles elevate the jaw at the TMJ?

Answer 2

1. Masseter
2. Temporalis
3. Medial pterygoid

Question 3

What muscles retract the jaw?

Answer 3

• Posteroinferior part of the temporalis

Question 4

What muscles ab and adduct the mandible?

Answer 4

Side to side grinding of the teeth is by:

• Lateral and medial pterygoids
• Note: the right pterygoids move the jaw to the left and vice versa*

Question 5

What innervates the muscles of the TMJ?

Answer 5

The masseter, temporalis, and medial & lateral pterygoids are innervated by the mandibular division of the trigeminal nerve (CN V3).

Question 6

What innervates the muscles of facial expression?

Answer 6

• CN VII: the facial nerve

Question 7

Action of buccinator muscle

Answer 7

The buccinator muscle is the muscle of the cheek. It assists in positioning a bolus of food between the molar teeth for grinding (but the movements at the TMJ are caused by muscles of mastication).

Question 8

What is the general anatomy of a tooth?

Answer 8

The parts of the tooth include the crown, neck, and root.

Question 9

What are the joints of the teeth?

Answer 9

The teeth are secured by gomphoses (fibrous joints of the ‘peg in socket’ variety) to the superior alveolar process of the maxilla and the inferior alveolar process of the mandible.

Question 10

Describe the inervation of the teeth

Answer 10

The superior alveolar nerves, branches of the maxillary division of the trigeminal nerve (CN V2 – the 2nd division of cranial nerve V = 5), innervate the maxillary teeth.

The inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve (CN V3 – the 3rd division of cranial nerve V = 5), innervates the mandibular teeth.

Question 11

Innervation of the muscles of the tongue

Answer 11

The muscles of the tongue (intrinsic and extrinsic) are innervated by the hypoglossal nerve, CN XII (cranial nerve 12). There’s one exception: the palatoglossus is innervated by the vagus nerve, CN X (cranial nerve 10).

Question 12

Sensory innervation of the muscles of the tongue

Answer 12

Sensory innervation of the tongue includes general sensation (touch, pain, temperature) and the special sensation of taste.

For general sensation, the anterior 2/3 of the tongue is innervated by the mandibular division of the trigeminal nerve (CN V3 – the 3rd division of cranial nerve 5), while the posterior 1/3 of the tongue is supplied by the glossopharyngeal nerve (CN IX – cranial nerve 9).

For taste, the anterior 2/3 of the tongue is innervated by the facial nerve (CN VII – cranial nerve 7), while the posterior 1/3 of the tongue is supplied by the glossopharyngeal nerve (CN IX – cranial nerve 9) (again!).

Question 13

Describe the parasympathetic innervation of the salivary glands

Answer 13