Dermatomes & Myotomes

Question 1

Dermatome

Answer 1

Sensory distribution of each nerve root

Question 2

Dermatome defined as

Answer 2

Area of skin supplied by a single nerve root. The area innervated by a nerve root is larger than that innervated by a peripheral nerve

Question 3

31 spine segments on each side give rise to…

Answer 3

31 spinal nerves
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal spinal nerve

Question 4

Dermatomes exist for each of these spinal nerves, except the

Answer 4

first cervical spinal nerve

Question 5

Sensory information from a specific dermatome is transmitted by the sensory nerve fibers to

Answer 5

the spinal nerve of a s specific segment of the spinal cord

Question 6

Pressure on nerve roots leads to loss of muscle tone and mass, but the loss is often not as obvious as when pressure is applied to a peripheral nerve.

Answer 6

Because the peripheral nerve that innervates the muscle is usually supplied by more than 1 nerve root, more muscle fibers are likely to be affected and wasting or atrophy is more evident if the peripheral nerve itself is damaged.

Question 7

C1

Answer 7

Vertex of skull

Question 8

C2

Answer 8

Temple, forehead, occiput

Question 9

C3

Answer 9

Entire neck, posterior cheek, temporal area, prolongation forward under mandible

Question 10

C4

Answer 10

Shoulder area, clavicular area, upper scapular area

Question 11

C5

Answer 11

Deltoid area, anterior aspect of entire arm to base of thumb

Question 12

C6

Answer 12

Anterior arm, radial side of hand to thumb and index finger

Question 13

C7

Answer 13

Lateral arm and FA to index, long, ring fingers

Question 14

C8

Answer 14

Medial arm and FA to long, ring, and little fingers

Question 15

T1

Answer 15

Medial side of FA to base of little finger

Question 16

T2

Answer 16

Medial side of upper arm to medial elbow, pectoral and mid-scapular areas

Question 17

T3-T12

Answer 17

T3 - T6 upper thorax
T5 - T7 costal margin
T8 - T12 abdomen and lumbar region

Question 18

L1

Answer 18

Back, over trochanter and groin

Question 19

L2

Answer 19

Back, front of thigh to knee

Question 20

L3

Answer 20

Back, upper buttock, anterior thigh and knee, medial lower leg

Question 21

L4

Answer 21

Medial buttock, lateral thigh, medial leg, dorsum of foot, big toe

Question 22

L5

Answer 22

Buttock, posterior and lateral thigh, lateral aspect of the leg, dorsum of foot, the medial half of sole, first, second, and third toes

Question 23

S1 and S2

Answer 23

Buttock, thigh, and leg posterior

Question 24

S3

Answer 24

Groin, medial thigh to knee

Question 25

S4

Answer 25

Perineum, genitals, lower sacrum

Question 26

Myotomes

Answer 26

Group of muscles innervated by a single spinal nerve root. Clinically useful as they can determine if damage has occurred to the spinal cord, and at which level the damage has occurred.

Question 27

M : C1 - C2

Answer 27

Cervical Flexion

Question 28

M: C3

Answer 28

Cervical Side Flexion

Question 29

M: C4

Answer 29

Scapular Elevation

Question 30

M: C5

Answer 30

Shoulder abduction

Question 31

M: C6

Answer 31

Elbow flexion and wrist extension

Question 32

M: C7

Answer 32

Elbow extension and wrist flexion

Question 33

M: C8

Answer 33

Thumb extension

Question 34

M: T1

Answer 34

Finger abduction

Question 35

M: L1 - L2

Answer 35

Hip flexion

Question 36

M: L3

Answer 36

Knee extension

Question 37

M: L4

Answer 37

Ankle dorsiflexion

Question 38

M: L5

Answer 38

Big toe extension

Question 39

M: S1

Answer 39

Ankle eversion and Plantarflexion, hip extension

Question 40

M: S2

Answer 40

Knee Flexion

Question 41

M: S3

Answer 41

No specific test action; intrinsic foot muscles (except abductor hallucis)