Dermatomes, Myotomes, Nerve Roots

Question 1

C2

Answer 1

Back of head

Question 2

C5

Answer 2

Shoulder, lateral arm

Question 3

C6

Answer 3

Lateral forearm and digits 1-2

Question 4

C7

Answer 4

Digit 3

Question 5

T10

Answer 5

Umbilicus

Question 6

L4

Answer 6

Knee and medial lower leg

Question 7

L5

Answer 7

Dorsal foot

Big toe

Question 8

S1

Answer 8

Lateral food, small toe, and sole

Question 9

Dermatome definition

Answer 9

Spiral nerves innervate the skin in an orderly, rostral-caudal arrangement

Touch skin to test spinal nerve and cord segment

Question 10

Myotome

Answer 10

Muscles innervated by spinal nerves

Tested with muscle strength test

Question 11

Effect of L4 Nerve Root Lesion

Answer 11

Reduced patellar tendon reflex
Weakness in iliopsoas, quads
Sensory loss in

Question 12

L5 Nerve Root Lesion

Answer 12

Sensory loss in dorsal of big toe

Weakness in foot dorsifexion, big toe extension, foot eversion, inversion

Question 13

S1 Nerve Root Lesion

Answer 13

Weakness in foot plantar flexion
Decreased Achilles’ tendon reflex
Sensory abnormality in lateral foot, small toe

Question 14

C5 Nerve Root Lesion

Answer 14

Weakness in deltoid, infraspinatus, biceps
Reflex decreased in biceps and pectoralis
Sensory abnormality in shoulder, upper lateral arm

Question 15

C6 Nerve Root Lesion

Answer 15

Weakness in wrist extensors, biceps
Reflex decreased in biceps and brachioradialis
Sensory symptoms in first and second fingers, lateral forearm

Question 16

C7 Nerve Root Lesion

Answer 16

Weakness in triceps
Reflex decreased in triceps
Sensory abnormality in middle finger