Dermatomes

Question 1

C2

Answer 1

At least 1cm lateral to occiptal protuberance at the base of the skull

At least 3cm behind the ear

Question 2

C3

Answer 2

In the supraclavicular fossa, at the midclavicular line

Question 3

C4

Answer 3

Over the acromioclavicular joint

Question 4

C5

Answer 4

On the lateral (radial) side of the antecubital fossa just proximal to the elbow (see image below)

Question 5

C6

Answer 5

On the dorsal surface of the proximal phalanx of the thumb

Question 6

C7

Answer 6

On the dorsal surface of the proximal phalanx of the middle finger

Question 7

C8

Answer 7

On the dorsal surface of the proximal phalanx of the little finger

Question 8

T1

Answer 8

On the medial (ulnar) side of the antecubital fossa, just proximal to the medial epicondyle of the humerus

Question 9

T2

Answer 9

At the apex of the axilla

Question 10

T3

Answer 10

At the midclavicular line

3rd coastal space

Found by palpating the anterior chest to locate the third rib and the corresponding third intercostal space below it

Question 11

T4

Answer 11

At the midclavicular line

4th intercostal space

Located at the level of the nipples

Question 12

T5

Answer 12

At the midclavicular line

5th intercostal space

Located midway between the level of the nipples and the level of the xiphisternum

Question 13

T6

Answer 13

At the midclavicular line

Located at the level of the xiphisternum

Question 14

T7

Answer 14

At the midclavicular line

1/4 of the distance between the level of the xiphisternum and the level of the umbilicus

Question 15

T8

Answer 15

At the midclavicular line

1/2 of the distance between the level of the xiphisternum and the level of the umbilicus

Question 16

T9

Answer 16

At the midclavicular line

3/4 of the distance between the level of the xiphisternum and the level of the umbilicus

Question 17

T10

Answer 17

At the midclavicular line

Located at the level of the umbilicus

Question 18

T11

Answer 18

At the midclavicular line

Midway between the level of the umbilicus and the inguinal ligament

Question 19

T12

Answer 19

At the midclavicular line

Over the midpoint of the inguinal ligament

Question 20

L1

Answer 20

Midway between the key sensory points for T12 and L2

Question 21

L2

Answer 21

On the anterior-medial thigh

At the midpoint drawn on an imaginary line connecting the midpoint of the inguinal ligament and the medial femoral condyle

Question 22

L3

Answer 22

At the medial femoral condyle above the knee

Question 23

L4

Answer 23

Over the medial malleolus

Question 24

L5

Answer 24

On the dorsum of the foot at the third metatarsal phalangeal joint

Question 25

S1

Answer 25

On the lateral aspect of the calcaneus

Question 26

S2

Answer 26

At the midpoint of the popliteal fossa

Question 27

S3

Answer 27

Over the ischial tuberosity or infragluteal fold (depending on the patient their skin can move up, down, or laterally over the ischii)

Question 28

S4/5

Answer 28

In the perianal area, less than one cm lateral to the mucocutaneous junction