November 7

Question 1

Accessory Nerve Course

Answer 1

Accesory nerve has 2 parts: Cranial part and spinal part.
The cranial part arises from the nucleus ambiguus of the medulla oblongata along with the vagus nerve and pass through the jugular foramen. after that it passes throught the carotid sheath along with the vagus nerve to become the pharyngeal plexus with the vagus and glossopharyngeal nerve to supply some of the palatal muscles of the pharynx.

The spinal part arises from the lateral funiculus of C1- C5, enters through foramen magnus and exits through the jugular foramen along with the cranial part of the accesory nerve and the vagus nerve. the spinal part them moves through the carotid sheath and move through the atlas and below the styloid process, the occipital artery and the digastric muscle to pierce the sternocleidomastoid muscle and supply that muscle.

Question 2

Muscles supplied by the accessory nerve

Answer 2

Sternocleidomastoid( C2 and C3) and Trapezius ( C3 and C4) - suppled by the spinal accessory nerve

Question 3

Pharyngeal Plexus

Answer 3

The pharyngeal plexus is a group of fine, ramifying nerve fibres on the posterior aspect of the pharynx which are centred around the middle constrictor muscles. They are derived from several sources:

pharyngeal branches of the vagus nerve; supply:
efferent motor fibres from the cranial part of the accessory nerve which originate within the nucleus ambiguus
afferent general somatic fibres originating in the sensory nucleus of the trigeminal nerve
pharyngeal branches of glossopharyngeal nerve; supplies afferent fibres from the pharyngeal mucosa. Note that the glossopharyngeal branch to stylopharyngeus is entirely separate.
cervical sympathetic fibres; vasoconstrict within the pharynx

Question 4

Abductor Pollicis Brevis

Answer 4

Origin - scaphoid, trapezium and flexor retinaculum
Insertion - Proximal phalanx of thumb and radial sesamoid bone
Innervetion - Reccurent branch of the median Nerve
Function - Abduction, Medial Rotation and Extension.

Question 5

Adductor Pollicis

Answer 5

Muscle of the thenar emminence
Origin - Transverse head originates from the third metacarpal bone. Olique Head originates from the capitate bone and the base of the 2nd and 3rd metacarpal bone.
Insertion - Proximal phalanx of the thumb and dorsal aponeurosis of the thumb.
Innervation - Deep branch of the ulnar nerve
Function - Adduction and Opposition.