5. Control of Jaw, Tongue and Soft Palate

Question 1

What nerve supplies the muscles of mastication?

Answer 1

Mandibular branch of trigeminal nerve

Question 2

Name some of the muscles of mastication that are supplied by the mandibular branch of the trigeminal nerve.

Answer 2

• Masseter
• Temporalis
• Medial and lateral pterygoids

(Lateral pterygoid is the only one that opens the jaw, the rest close it)

Question 3

What is the jaw jerk reflex?

Answer 3

• If the mouth is held slightly open and the lower jaw tapped sharply from above with a reflex- testing hammer the jaw will close and open again rapidly.
• This is a monosynaptic ‘stretch reflex’ involving primarily masseter and temporalis.

Question 4

Summarise the innervation of the tongue.

Answer 4

• Muscle supply = Hypoglossal nerve
• Sensation in anterior 2/3rds = Trigeminal nerve
• Taste in anterior 2/3rds = Facial nerve
• Sensation and taste in posterior 1/3rd = Glossopharyngeal nerve

Question 5

How does a hypoglossal nerve lesion present?

Answer 5

The tongue deviates towards the side of a peripheral lesion, and to the opposite side of a central lesion.

Question 6

Describe the spread of carcinoma of the tongue.

Answer 6

Spreads from the tip to lower deep cervical nodes, and from the body to the submandibular and upper deep cervical nodes.

Question 7

What senses the gag reflex?

Answer 7

The soft palate, via the glossopharyngeal nerve.

Question 8

What is jugular foramen syndrome?

Answer 8

Paralysis of the IX, X, and XI cranial nerves traversing the jugular foramen.