Lecture 4: innervation

Question 1

the dermis and the epidermis originate from what, respectively?

Answer 1

the dermis is mesoderm, the epidermis is the ectoderm

Question 2

hypaxial muscles and epaxial muscles, def:

Answer 2

skin and limbs of the trunk, intrinsic back muscles

Question 3

what does the spinal chord come from?

Answer 3

the neural tube

Question 4

where are the cell bodies that inneravate a myotome located? what do they innervate?

Answer 4

in the spinal chord, a muscle group

Question 5

what is the embryological origin of the dorsal root ganglion

Answer 5

the neural crest

Question 6

cells that innervate dermatomes are located

Answer 6

outside the spinal cord, in the DRG

Question 7

what information does a spinal nerve carry?

Answer 7

motor input to a muscle, sensory input back to the sc

Question 8

in terms of morphology, motorneurons are said to be this type, while sensory neurons are said to be this type

Answer 8

multipolar, psuedounipolar

Question 9

how many vertibral segments of each type do we have?

Answer 9

7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral and coccyx

Question 10

with what structure does the spinal cord end, and where does it terminate?

Answer 10

conus medullaris, L1/L2

Question 11

what is the cauda equina?

Answer 11

formed of PNS nerves, even though they are within the vertibral collumn. off of conus medularis

Question 12

what structure provides longitudinal support to the spinal cord?

Answer 12

filum terminale

Question 13

where is CSF? at what meningeal layer?

Answer 13

between the pia and arachnoid

Question 14

how many pairs of cervical nerves are there?

Answer 14

8

Question 15

what type of information does the ventral root carry

Answer 15

motor, efferent

Question 16

what type of information does the dorsal root carry

Answer 16

sensory, afferent

Question 17

which spinal level has the most grey matter?

Answer 17

L3 (c5 also has a lot)

Question 18

what do gamma mn do?

Answer 18

d contract the muscle spindle in coordination with the muscle fiber

Question 19

reflexes start with, and end with. may be blank

Answer 19

afferent feedback, end with motor output, may be mono or poly synaptic.

Question 20

the following branches off the brachial plexus contain only sensory information

Answer 20

median antebrachial cutaneous, superficial radial

Question 21

most branches off the brachial plexus contain both motor and sensory info, including

Answer 21

the axillary, (deep) radial –posterior interosseus, median, ulnar, musculocutaneous

Question 22

medial antebrachial cutaneous innervation, by, where?

Answer 22

T1, c8, medial forearm, from wrist, to above elbow

Question 23

medial brachial cutaneous innervation, by, where

Answer 23

T1, c8, medial upper arm below armpit

Question 24

musculocutaneous nerve, by, where?

Answer 24

C5, C6, c7, lateral forarm

Question 25

ulnar nerve, by, where?

Answer 25

C8, T1,front and back pinky side of the hand

Question 26

median nerve, by, where?

Answer 26

C5, C6, C7, C8, T1, palm side, thum to inner ring, tips of digits (sensory)

Question 27

what are the motor functions of the median nerve?

Answer 27

wrist flexors, pronators, lumbricals 1&2, nothing in upper arm, thenar muscles

Question 28

what are the motor functions of the ulnar nerve?

Answer 28

wrist flexors, hypothenar muscles, lumbricals 3&4 adductor pollicis, dorsal and palmar interossi

Question 29

what are the motor functions of the radial nerve? spinal?

Answer 29

extensors of the forearm, C5-T1

Question 30

what are the sensory functions of the radial nerve?

Answer 30

lateral and posterior upper arm, posterior fore arm, radial 1/2 of palm (lateral)

Question 31

what are some features of an upper mn injury?

Answer 31

paralysis, muscle wasting, spacticity, hypertonicity, hypereflexia

Question 32

what are some features of a lower mn injury?

Answer 32

flacidity, hypotonicity, hyporeflexia