Cranial Nerves

Question 1

What type of nervous system for segmental trunk nerves

Answer 1

1. Somatic nervous system under voluntary control, conscious

Question 2

How does the reflex arc of segmental trunk nerves occur?

Answer 2

1 = afferent (sensory) = back to brain
2-3 = inter neruone in spinal cord
4 = Efferent (motor) coming out

Question 3

What is an important concept with the spinal nerves roots?

Answer 3

1. you have both dorsal and ventral roots (nerve fibres coming into the spinal cord in the top and bottom)
2. spinal segmental nerves almost immediately fuse = looks like a single nerve going into or coming out of the cord.
3. So from anatomical point of view looks like a single nerve but is just a fusion or dorsal and ventral roots

Question 4

Where does the autonomic efferent neurones come out of the spine and head

Answer 4

1. Head = top: dorsal root nerves

2. Spine = bottom: ventral root nerves

Question 5

What is different about the dorsal and ventral segmental nerves coming out of the head

Answer 5

No fusion of dorsal and ventral roots- they stay as separate nerves

Question 6

What are striated muscle arising from lateral plate mesoderm innervated and where do they leave?

Answer 6

Innervated = Special visceral efferents

2. Leave = via dorsal root

Question 7

What is the relationship between the pharyngeal arch and segment

Answer 7

1. Segment 1 has no pharyngeal arch

2. so arch is always numbered 1 behind the segment that they’re in.

Question 8

What is the dorsal root nerve of segment 2 like and why

Answer 8

1. Due to development of mouth it separates segment 2 into 2 areas anatomically .
2. so one of the nerves has to splits into 2 major divisions (maxillary and mandibular divisions of V)

Question 9

What is the nerve supply to 4 and 5 and why

Answer 9

No ventral root nerve as lose their somites

Question 10

What is the nerve supply like for segment 6 (and 7)

Answer 10

1. segment 6 lost P arch so DORSAL nerve doesn’t exist
2. Seg 6 and 7 somites unite to form tongue muscles
3. Seg 6 and 7 Ventral root nerve unites

Question 11

Segment 5 and 7

Answer 11

SEg 5 and 7 share theri DORSAL root nerve (X/ XI)