Dermatomes, Myotomes, and Spinal Nerve Plexuses

Question 1

5 Contrast segmental innervation with innervation via plexus formation

segmental innervation

Answer 1

a single posterior spinal root fiber innervating a single area of skin with an afferent nerve (sensory)

Question 2

innervation via plexus formation

Answer 2

includes the effects of an entire peripheral nerve, which may include one or more dermatomes

Question 3

what’s the difference between a dermatome and a nerve map?

Answer 3

a dermatome map includes a single sensory roots path and effect

nerve map is the map and effect of an entire peripheral nerve, which may include more than one dermatome

Question 4

brachial plexus components (just the terminal branches)

Answer 4

musculocutaneous
axillary
radial
ulnar
median
medial brachial cutaneous n.
medial antebrachial cutaneous n.

Question 5

Musculocutaneous

Answer 5

C5-C7

Question 6

Median

Answer 6

C6-T1

Question 7

Ulnar

Answer 7

C8-T1

Question 8

Radial

Answer 8

C5-T1

Question 9

Medial branchial cutaneous n.

Answer 9

C8-T2

Question 10

Medial antebrachial cutaneous n.

Answer 10

C8-T1

Question 11

Branches of lumbosacral

Answer 11

Femoral n
Obturator n
Sciatic n 
Lateral Femoral Cutaneous n 
Posterior femoral cutaneous

Question 12

Femoral n.

Answer 12

L2-L4

Question 13

Obturator

Answer 13

L2-L4

Question 14

Sciatic n.

Answer 14

L4-S3

Question 15

Lateral femoral cutaneous n.

Answer 15

L2-L3

Question 16

Posterior femoral cutaneous n.

Answer 16

S1-S3

Question 17

Lesions in C1-C7 would lead to

Answer 17

fully paraplegic

Question 18

lesions in T1-T12

Answer 18

lower extremity paraplegia

Question 19

lesions in L1-L5

Answer 19

impaired walking

Question 20

lesions in S1-S5 and conus equina

Answer 20

impaired but good walking