General Intro To Cranial Nerves

Question 1

What do the cranial nerves supply?

Answer 1

Tissues of the head and neck region
Glossopharyngeal and vagus also supply viscera out of the head and neck region

Question 2

Where do the cranial nerves exist the brain?

Answer 2

Inferior surface apart from one which emerges from the superior surface

Question 3

Most cranial nerves are typical of ‘peripheral nerves’. 2 are apical, which are these are why?

Answer 3

The optic and olfactory nerves are atypically as they are true brain tracts rather than peripheral nerves. Their connective tissue envelopes are not the same as most peripheral nerves, but instead ensheathed by the meninges. They contain CSF so almost like tracts rather than nerves.

Question 4

What are the 2 criteria for spinal nerve fibres?

Answer 4

Criterion 1: general functional classification of nerves must be somatic or autonomic (or visceral)
Criterion 2: the direction of conduction of impulses by the nerves is afferent or efferent

Question 5

What are the 4 general classes of spinal/peripheral nerves? (Cranial nerves also have these classifications)

Answer 5

General somatic afferents (GSA) - responsible for general sensation - localisable pain
General visceral afferents (GVA) - nerves that carry sensation from visceral organs to CNS, so visceral sensation - less localised, more discomfort
General somatic efferents (GSE) - supply skeletal muscle
General autonomic efferents (GVE) - autonomic fibres innervating visceral structures

Question 6

What are the 3 extra classifications found in only cranial nerves?

Answer 6

Special visceral efferent - muscles derived from branchial arches (CNV, VI, IX, X)
Special somatic afferent - equilibration, hearing, sight
Special visceral afferent - taste

Question 7

Rostral to caudal arrangement of nerves

Answer 7

CNI is the most rostral
CNXI is the most caudal
CNXII is the exception, being just in front of CNXI