Cranial Nerves

Question 1

What kind of lesions can happen to CN I?

Answer 1

Fractured anterior cranial fossa, anopsi on of olfactory nerve fibers, tumors.
*causes anosmia- loss of sense of smell

Question 2

What muscles are innervated by CN III

Answer 2

Medial rectus, inferior rectus, superior rectus, inferior oblique.
ADD, downward gaze, upward gaze, and extorsion
OCCULOMOTOR

Question 3

What muscles are innervated by CN IV

Answer 3

Superior oblique
Intorsion, inferior rotation, downward movement
TROCHLEAR

Question 4

What muscles are innervated by CN VI

Answer 4

Lateral rectus
Abduction
ABDUCENS

Question 5

Where do the somatic motor nerves originate for CN III?

Parasympathetic fibers?

Answer 5

Oculomotor nucleus in posterior midbrain.
Nerves exit through superior orbital fissure

Edinger-westphal nucleus superior to Oculomotor nucleus for preganglionic fibers. Ciliary ganglion for postganglionic fibers. Controls pupillary light reflex and accommodation reflex (changes lens for better near vision)

Question 6

Name second order neuron nuclei and what they sense from sensory part of CN V

Answer 6

Mesencephalic - proprioception (superior brainstem: midbrain and upper pons)
Main Sensory - discriminative sense (mid to lower pons)
Spinal Trigeminal - pain and temperature (medulla and upper SC)

Question 7

Which would most likely be damaged with crus cerebri lesion?

Answer 7

Oculomotor

Question 8

Where do the second order neurons synapse from sensory CN V?

Answer 8

Synapse on third order neurons in VPM then project to “face” SS cortex

Question 9

Describe the factory nerve track

Answer 9

First order neurons are olfactory receptor cell located in the mucosal lining of nasal cavity. These axons pass through the cribriform plate forming the olfactory nerve. Axons synapse on second order Neurons in the olfactory bulb. These axons form the olfactory tract and project posteriorly to primary olfactory cortex -Amygdala.