OT 531 Musculoskeletal Anatomy (Dermatomes and Myotomes)

general explanation of dermatomes

unilateral area of skin of skin supplied by a single spinal n.

*dermatome area doesn't always supply the muscles beneath it (T1 example- myotome= intrinsic muscles of the hand, dermatome= medial elbow and inferior arm)

general explanation of myotomes

unilateral muscle mass supplied by a single spinal nerve

unilateral

means stays on the same side of body (does not cross)

list dermatomes and what part of the skin they innervate

C3, 4= root of neck, extending over shoulder

C5= lateral aspect of arm and elbow region

C6= lateral aspect of forearm and thumb

C7= region of middle finger, center posterior aspect of forearm

C8= little finger, medial hand, medial aspect of forearm

T1= medial elbow and inferior arm

T2= medial superior arm and axilla

list myotomes and which muscles/area they will innervate

1. glenohumeral joint (shoulder)

-lateral rotation, abduction, flexion= C5

-medial rotation, adduction, extension= C6, 7, 8

2. elbow joint

- flexion= C5, 6

-extension= C6, 7

3. wrist

-flexion, extension= C6, 7

4. radio-ulnar joint

- supination= C6

-pronation= C7, 8

5. MP and IP joints by forearm muscles

-digital flexion and extension= C7, C8

6. intrinsic muscles of the hand= T1

7. reflex testing of spinal segments (afferent and efferent limbs)

- biceps= C5, 6

-triceps= C7