Introduction to Cranial Nerves

Question 1

How many paris of spinal nerves are there compared to cranial nerves?

Answer 1

31 pairs of spinal nerves

12 pairs of cranial nerves

Question 2

How do spinal nerves and cranial nerves differ in their fiber content?

Answer 2

1. spinal nerves are mixed - motor and sensory
2. cranial nerves can be mixed, only motor, or only sensory

Question 3

What 2 cranial nerves are actually tracts because they don’t have nuclei - they just stay in the brain?

Answer 3

Cranial nerves 1 and 2

Question 4

What is the only CN that comes out the dorsal side of the brain?

Answer 4

trochlear

Question 5

What eye muscle is controlled by the trochlear nerve?

Answer 5

superior oblique

Question 6

What eye muscle is controlled by the abducens nerve?

Answer 6

the lateral rectus - controls eye movement in a horizontal plane

Question 7

How many nerves are associated with the forebrain, midbrain, pons, or medulla respectively?

Answer 7

2 with the forebrain (1 and 2)

2 with the midbrain (3 and 4)

4 with the pons (5-8)

4 with the medulla (9-12)

Question 8

In general, how are nerves arranged based on embryological development?

Answer 8

the alar plate has sensory fibers and the basal blate as motor fibers

as the medulla upens up , the plates go with it so that the alar (sensory) is lateral while the basal (motor) is medial

These are separated by the sulcus limitans and viseral innervarion is located near the sulcus

Question 9

WHat does the inferior colliculus do? How about the superior colliculus?

Answer 9

inferior = audition

superior = ocular revlexes

Question 10

What do fibers do at the pyramidal decussation?

Answer 10

they cross over to the other side

Question 11

What are pattern generators, and how can they occur?

Answer 11

It’s an “autopilot” type of coordinated response which is activtated when a command domes down from the motor cortex to the brainstem neurons

It’s possible because th eneurons are wired together in such a way that pools of neurons are activated in the right order and timing to make the response occur

(examples are chewing, swalowing, breathing, etc)

Question 12

What ist he “packing material” of the cranial nerve nuclei?

Answer 12

the reticular formation

Question 13

If the caudal medulla looks like a squished spinal cord, what is the “dorsal horn” area associated with?

Answer 13

the trigeminal nerve

Question 14

WHat type of sensation if the medial lemniscus associated with?

Answer 14

proprioceptive, light touch, vibration

Question 15

What types of touch are associated with the spinal thalamic tract?

Answer 15

pain and temperature

Question 16

What is the corticospinal tract associated with? Where does it cross/

Answer 16

Voluntary motor

crosses at the pyramidal decussation