Anatomy

Question 1

Which structures pass through the parotid gland?

Answer 1

Lateral to medial:

1. Facial nerve (Mnemonic: The Zebra Buggered My Cat; Temporal Zygomatic, Buccal, Mandibular, Cervical)
2. Retromandibular vein
3. External carotid artery
4. Superficial temporal artery
5. Auriculotemporal nerve
6. Maxillary artery

Question 2

What does the median nerve supply in the hand?

Answer 2

Motor: LOAF

Sensory: Palmar surface - thumb and lateral 2 1/2 fingers. Dorsal surface - distal 2 1/2 fingers.

Question 3

What occurs on damage to the median nerve at:

1. The wrist?
2. The elbow?
3. Anterior interosseus nerve?

Answer 3

1. Thenar wasting, LOAF function impaired, sensory loss to radial 2 1/2 fingers.
2. As above plus inability to pronate, ulnar deviation of wrist
3. Loss of pronation and weakness of long flexors of thumb and index finger

Question 4

What is the mechanism of phonation (voice production)?

Answer 4

1. Superior laryngeal nerve (innvervates cricothyroid - adjusting tension of vocal fold for high notes) = abnormalities in pitch, inability to sing with smooth change to each higher note
2. Recurrent laryngeal nerve (innervates intrinsic larynx muscles) - opens vocal folds (breathing/coughing), closing vocal folds for vibration during voice use, closing vocal folds during swallowing

Question 5

What are the boundaries of the inguinal canal?

Answer 5

Floor: external oblique aponeurosis, inguinal ligament, lacunar ligament

Roof: internal oblique, transversus abdominis

Anterior wall: external oblique aponeurosis

Posterior wall: transversalis fascia, conjoint tendon

Lateral: internal ring, transversalis fascia, fibres of internal oblique

Medial: external ring, conjoint tendon

Question 6

What is the difference between neuropraxia and neurotmesis?

Answer 6

Neuropraxia - temporary loss of sensation/motor due to nerve damage, fully returning after several weeks. No loss of axonal continuity.

Axonotmesis - loss of relative continuity of axon and myelin sheath, but connective tissue intact. Motor and sensory function distal to lesion. Axonal regeneration occurs without surgical Rx.

Neurotmesis - total severence/disruption of nerve fibre. Complete recovery impossible. Surgical intervention necessary.

Question 7

Which structures pass through the foramen ovale?

Answer 7

Foramen ovale:

1. Otic ganglion
2. V3
3. Accessory meningeal artery
4. Lesser petrosal nerve
5. Emissary veins