Anatomy

Question 1

1. Draw course of CNV2

2. Draw course of CNV3

Answer 1

CNV2 leaves BoS at foramen rotundum. It tracks down towards the pterygopalatine fossa, giving off the pharyngeal branch on its way. It gives off 3 branches around the pterygopalatine ganglion (nasopalatine and nasal branches), before continuing its course towards the IOF, giving off greater and lesser palatine nerves, zygomatic nerve and posterior superior alveolar nerve en route. At the inferior orbital fissure, the maxillary nerve becomes the infraorbital nerve. It gives off middle and anterior superior alveolar nerves before exiting the infraorbital foramen and terminating as palpebral, nasal and labial branches.

CNV3 leaves BoS at foramen ovale. Travels down, giving off the branch to the medial pterygoid and the auticulotemporal branch, before dividing into an anterior and posterior branch. The anterior branch supplies the remaining muscles of mastication (masseter, deep temporal branches and lateral pterygoid), before terminating as the buccal branches. The posterior branch divides into the lingual nerve (giving off the chordates tympani) and the inferior alveolar nerve, which also gives off the nerve to mylohyoid before terminating as the mental nerve.

Question 2

1. Describe neuroanatomy of a stroke
2. Describe differences between stroke and facial palsy
3. Management of facial palsy

Answer 2

1. Occurs due to an interruption in the blood supply/rupture of a blood vessel in the brain. Causes loss of blood supply (ischaemia/pressure compresses BVs from haematoma) to certain areas of the brain. An interruption in the supra-nuclear fibres from the motor areas of the cerebral cortex causes the opposite 2/3 of the face to begin to ‘droop’ due to loss of motor function.
2. Stroke - affects opposite side of face to hemisphere affect. Also can’t raise arms. Only lower 2/3 of face affected (only receives crossed fibres from opposite hemisphere), as upper 1/3 of face receives both crossed and uncrossed fibres (from both hemispheres).
   Facial palsy - due to injection of LA from IDB into parotid gland (to far back, no contact with bone). LA trapped within the dense tissue, within the capsule of parotid gland, near to where CNVII branches/divides and so affects all branches of CNVII (affects entire side of face - same side of affected parotid gland)
3. Confirm not a stroke (close eyes, wrinkle forehead, raise and hold arms), explain what has happened, cover affected eye with dam gauze patch, reassure that sensation will return when LA wears off in a few hours - monitor or send home and follow up

Question 3

Muscles of mastication

For each, give:

1. Name
2. Function
3. Origin
4. Insertion

Answer 3

1. Masseter - elevation and protrusion of mandible
   Temporal process of zygomatic bone and zygomatic arch to angle and ramus of mandible
2. Temporalis - elevation and retrusion of mandible
   Temporal fossa and deep part of temporal fascia to coronoid process and anterior border of ramus of mandible
3. Medial pterygoid - elevation and protrusion of mandible
   Medial surface of lateral pterygoid plate and maxillary tuberosity to medial surface of ramus and angle of mandible
4. Lateral pterygoid - depression and protrusion of mandible
   Lateral surface of lateral pterygoid plate and infratemporal surface of greater wing of spheroid to neck of mandible and capsule/intracapsular disc