10- BRACHIAL PLEXUS, DERMATOMES AND MYOTOMES

Question 1

State the nerves of the spine and their number of pairs in order

Answer 1

1. Cervical nerves (8)
2. Thoracic nerves (12 pairs)
3. Lumbar nerves (5 pairs)
4. Sacral nerves (5 pairs)
5. Coccygeal nerve (1 pair)

Question 2

C5 and C6 contributes to which terminal nerve(s)?

Answer 2

Musculocutaneous and median nerves

Question 3

C7 contributes to which terminal nerve(s)?

Answer 3

Radial nerve

Question 4

C8 and T1 contribute to which terminal nerve(s)?

Answer 4

Median and ulnar nerves

Question 5

Which roots connect to the median nerve?

Answer 5

C5, C6, C8 and T1

Question 6

State the trunks of the Brachial Plexus

Answer 6

Superior, middle and inferior

Question 7

State the cords of the Brachial Plexus

Answer 7

Lateral, posterior and medial

Question 8

State the terminal branches (nerves) of the brachial plexus

Answer 8

Musculocutaneous nerve
Median nerve
Axillary nerve
Radial nerve
Ulnar nerve

Question 9

Which muscles do the musculocutaneous nerve trigger?

Answer 9

Coracobrachialis, Biceps and brachialis

Question 10

Which muscles do the axillary nerve trigger?

Answer 10

Deltoid and teres minor

Question 11

Describe the dermatome for C3 and C4

Answer 11

Region at base of neck, extending laterally over shoulder

Question 12

Dermatome of C5

Answer 12

Lateral aspect of arm (i.e superior aspect of abducted arm)

Question 13

Dermatome of C6

Answer 13

Lateral forearm and thumb

Question 14

Dermatome of C7

Answer 14

Middle and ring fingers(or middle three fingers) and center of posterior aspect of forearm

Question 15

Dermatome of C8

Answer 15

Little finger, medial side of hand and forearm (i.e, inferior aspect of abducted arm)

Question 16

Dermatome of T1

Answer 16

Medial aspect of forearm and inferior arm

Question 17

Dermatome of T2

Answer 17

Medial aspect of superior arm and skin axilla

Question 18

Root, nerve and muscle of shoulder abduction

Answer 18

C5
Axillary
Deltoid

Question 19

Root,nerve and muscle of elbow flexion

Answer 19

C5/C6
Musculocutaneous, radial
Biceps, brachioradialis

Question 20

Root,nerve and muscle of elbow estension

Answer 20

C7
Radial
Triceps

Question 21

Root,nerve and muscle of radial wrist extension

Answer 21

C6
Radial
Extensor carpi, radialis longus

Question 22

Root,nerve and muscle of finger extension

Answer 22

C7
Posterior interosseus nerve
Extensor digitorum communis

Question 23

Root,nerve and muscle of finger flexion

Answer 23

C8
anterior interosseus nerve
Flexor pollicis longus, flexor digitorum profundus (index)
Flexor digitorum profundus(ring +little)

Question 24

Root,nerve and muscle of finger abduction

Answer 24

T1
ulnar- first dorsal interosseus
median- abductor pollicis brevis

Question 25

Waiter’s tip deformity

Answer 25

Due to loss of lateral rotators of the shoulder, arm flexors, and hand extensor muscles

Question 26

Claw hand

Answer 26

Ulnar nerve is damaged

Imbalance between strong extrinsic muscles and weakened intrinsic muscles.

Question 27

Thoracic outlet syndrome

Answer 27

Compression of the brachial plexus.
Shoulder and neck pain.
Numbness and weak grip in the fingers