Mouth

Question 1

What structure can be palpated on the contracted masseter muscles?

Answer 1

Parotid duct

Question 2

What parts of the face are anaesthetised during an inferior alveolar nerve block? Where is the block injected?

Answer 2

• lower teeth
• 1st premolar, canine, incisor teeth & associated buccal gingiva via incisive branch
• chin & lower lip via mental nerve
• loss of sensation of ant. 2/3 of tongue via lingual nerve (anaesthetic spreads to lingual nerve, which is immediately anterior to the inf. alveolar nerve)

Injected on the medial border of the mandibular ramus (inner face of infratemporal fossa, as the inferior alveolar nerve enters the alveolar canal, anterior to medial pterygoid)

Question 3

Describe the structure of the tongue.

Answer 3

Terminal sulcus divides majority of tongue from pharyngeal part of the tongue

Foramen cecum at pharyngeal part of the tongue (attachment of thyroglossal duct, then obliterated)

Comprised of intrinsic & extrinsic muscles

Highly mobile; only connected to floor of the mouth by the lingual frenulum

Lies partly in the pharynx

Contribution from all pharyngeal arches (proliferations of mesenchyme)

Question 4

What is the innervation of the tongue?

Answer 4

SENSORY:

• anterior 2/3 = pharyngeal arches 1 & 3 = general sensory innervation (mandibular division of trigeminal nerve - CNV3 - and glossopharyngeal - CNIX)
• posterior 1/3 = pharyngeal arches 3 & 4 = general & special sensory innervation (glossopharyngeal- CNIX - & vagus - CNX)

TASTE: chorda tympani (branch of facial nerve - CNVII)

note: nerve of second pharyngeal arch but passes into first arch bia middle ear

MOTOR: both intrinsic & extrinsic muscle develop from myogenic precursors (occipital somites that migrate into the developing tongue) - hypoglossal nerve - CNXII

Question 5

What is the innervation of the parotid gland?

Answer 5

Auriculotemporal nerve (PS) from glossopharyngeal nerve (CNIX)

Question 6

How does a patient present with right hypoglossal nerve palsy?

Answer 6

Paralysis of right side of tongue —> atrophy of tongue on affected side
—> when protruded, the tongue deviates to the affected side (unopposed action of genioglossus on left side)

Question 7

What are the specific branches supplying the upper and lower teeth?

Answer 7

UPPER = superior alveolar nerve (maxillary division of trigeminal nerve)

LOWER = inferior alveolar nerve (mandibular division of trigeminal nerve)