Dermatomes/Myotomes/Reflexes

Question 1

C1

Answer 1

Dermatome: vertex of skull
Myotome: cervical rotation/flexion

Question 2

C2

Answer 2

Dermatome: temple, forehead, occiput (POSTERIOR HEAD)
Myotome: cervical flexion

Question 3

C3

Answer 3

Dermatome: Entire neck, posterior cheek, temporal area, prolongation forward under mandible (POSTERIOR-LATERAL NECK)
Myotome: cervical side flexion

Question 4

C4

Answer 4

Dermatome: Shoulder area, clavicular area, upper scapular area (AC JOINT)
Myotome: scapular elevation

Question 5

C5

Answer 5

Dermatome: Deltoid, anterior aspect of entire arm to thumb (LATERAL ARM)
Myotome: elbow flexion & shoulder abduction

Question 6

C6

Answer 6

Dermatome: anterior arm, radial side of hand to thumb and index finger (LATERAL ARM AND THUMB)
Myotome: wrist extension and elbow flexion

Question 7

C7

Answer 7

Dermatome: Lateral arm and forearm to index, long, and ring fingers (PALMAR DISTAL PHALANX MIDDLE FINGER)
Myotome: Elbow extension & wrist flexion

Question 8

C8

Answer 8

Dermatome: Medial arm and forearm to long, ring, and little fingers (LITTLE FINGER AND ULNAR BORDER OF HAND)
Myotome: thumb extension and finger flexion

Question 9

T1

Answer 9

Dermatome: Medial side of forearm to base of little finger (MEDIAL FOREARM)
Myotome: finger abduction

Question 10

T2

Answer 10

Dermatome: Medial side of upper arm to medial elbow, pectoral and midscapular regions
Myotome: n/a

Question 11

L1

Answer 11

Dermatome: Back, over trochanter and groin
Myotome: hip flexion

Question 12

L2

Answer 12

Dermatome: Back, front of thigh to knee (ANTERIOR THIGH)
Myotome: hip flexion

Question 13

L3

Answer 13

Dermatome: Back upper buttock, anterior thigh and knee, medial lower leg (MIDDLE THIRD OF ANTERIOR THIGH)
Myotome: knee extension

Question 14

L4

Answer 14

Dermatome: Medial buttock, lateral thigh, medial leg, dorsum of foot, big toe (PATELLA AND MEDIAL MALLEOLUS)
Myotome: Ankle DF

Question 15

L5

Answer 15

Dermatome: Buttock, posterior and lateral thigh, lateral aspect of leg, dorsum of foot, medial half of sole, first, second, and third toes (FIBULAR HEAD AND DORSUM OF FOOT)
Myotome: great toe extension (also glute med)

Question 16

S1

Answer 16

Dermatome: Buttock, thigh, and posterior leg, Lateral and plantar aspect of foot (LATERAL AND PLANTAR ASPECT OF FOOT)
Myotome: ankle PF, eversion and hip extension

Question 17

S2

Answer 17

Dermatome: Buttock, thigh, and posterior leg (MEDIAL POSTERIOR THIGH)
Myotome: Same as S1 except peroneals (Hamstrings, gluteals, PF), knee flexion

Question 18

S3

Answer 18

Dermatome: Groin, posteromedial thigh to knee
Myotome: No specific test but S3 – intrinsic foot muscles

Question 19

S4

Answer 19

Dermatome: Perineum, genitals, lower sacrum
Muscles: bladder, rectum

Question 20

T3-T6

Answer 20

Dermatome: upper thorax

Question 21

T5-T7

Answer 21

Costal margin

Question 22

T8-T12

Answer 22

Abdomen and lumbar region

Question 23

Corneal reflex

Answer 23

involuntary blinking in response to corneal stimulation

Question 24

Abdominal reflex (levels)

Answer 24

T7-T12
Contraction of superficial abdominal muscles when stroking abdomen lightly lateral to medial

Significant if asymmetric; signifies UMN lesion on absent side

Question 25

Cremasteric reflex

Answer 25

L1, L2 Contraction of cremaster muscle after stroking the same side of superior/inner thigh absent with SCI and corticospinal lesions

Question 26

Plantar reflex

Answer 26

S1,S2, tibial nerve PF of toes is elicited when stroking lateral sole of the foot from calcaneous to base of 5th met DF of great toe/fanning is abnormal "babinski" seen with corticospinal/UMN lesions

Question 27

Anal reflex

Answer 27

reflexive contraction of the external anal sphincter upon stroking the skin around the anus

Question 28

Bulbocavernosus reflex

Answer 28

S2-S4 Anal sphincter contraction in response to squeezing the glans penis or tugging on an indwelling Foley First reflex to come after SCI, indicator body is out of spinal shock

Question 29

How to grade deep tendon reflexes

Answer 29

0-4+ 0-none 1+ slight reflex, depressed 2+ normal, typical 3+ brisk reflex, not necessarily abnormal 4+ very brisk, abnormal, clonus

Question 30

Nerve roots involved in biceps reflex

Answer 30

C5-C6

Question 31

Main nerve roots involved in brachioradialis reflex

Answer 31

C5-C6

Question 32

Main nerve roots involved in triceps reflex

Answer 32

C7-C8

Question 33

Main spinal nerve roots involved in patellar reflex

Answer 33

L2-L4

Question 34

Main nerve roots involved in achilles tendon reflex

Answer 34

S1-S2

Question 35

Main nerve roots involved in hamstrings reflex

Answer 35

L5-S2