Brachial Plexus

Question 1

What is the brachial plexus formed from?

Answer 1

The ventral rami of C5-T1

Question 2

Which roots converge to form the superior trunk?

Answer 2

C5 + C6

Question 3

Which roots form the middle trunk?

Answer 3

C7

Question 4

Which roots converge to form the inferior trunk?

Answer 4

C8 + T1

Question 5

Which divisions is the lateral cord formed from?

Answer 5

Anterior division of the superior and middle trunk

Question 6

Which divisions is the posterior cord formed from?

Answer 6

The posterior divisions of the superior, middle and inferior trunk

Question 7

Which divisions is the medial cord formed from?

Answer 7

The anterior division of the inferior trunk

Question 8

What are the 5 terminal branches of the brachial plexus?

Answer 8

Remember MARMU
1. Musculocutaneous
2. Axillary
3. Radial
4. Median
5. Ulnar

Question 9

What are nerves which branch off before the terminal branches called?

Answer 9

Preterminal (collateral) branches

Question 10

Which cord and nerve roots does the median nerve arise from?

Answer 10

Arises from the lateral and medial cords
C5 - T1

Question 11

Which muscles in the anterior forearm does the median nerve innervate?

Answer 11

1. Flexor digitorum superficialis
2. Pronator quadratus
3. Flexor digitorum profundus (with ulnar nerve)

Question 12

Which muscles in the hand does the median nerve innervate? - think LOAF

Answer 12

Lateral 2 lumbricals, opponens brevis, abductor pollicis brevis, flexor pollicis brevis

Question 13

What is the sensory innervation of the median nerve?

Answer 13

1. Palmar - lateral 3.5 digits and adjacent palm
2. Dorsal - distal aspects of the lateral 3.5 digits (tips of these fingers)

Question 14

Which cord and nerve roots does the musculocutaneous nerve arise from?

Answer 14

Arises from the lateral cord
C5 - C7

Question 15

Which muscles does the musculocutaneous nerve innervate?

Answer 15

1. Corabrachialis
2. Biceps brachii
3. Brachialis

Question 16

Where is the sensory innervation of the musculocutaneous nerve located?

Answer 16

Lateral side of forearm

Question 17

Which cord and nerve roots does the axillary nerve arise from?

Answer 17

Arises from the posterior cord of the brachial plexus
C5 - C6

Question 18

Which muscles does the axillary nerve innervate?

Answer 18

1. Deltoid
2. Teres minor

Question 19

What is the sensory innervation of the axillary nerve?

Answer 19

1. glenohumeral joint
2. skin covering the inferior portion of the deltoid (sergeants patch)

Question 20

Which cord and nerve roots does the radial nerve arise from?

Answer 20

Arises from the posterior cord
C5 - T1

Question 21

Which muscles does the radial nerve innervate?

Answer 21

All muscles of the posterior arm and forearm. This includes the tricpes brachii, anconeus, brachioradialis muscle and the wrist extensors and long muscles of the thumb

Question 22

What is the sensory innervation of the radial nerve?

Answer 22

Skin of the posterior forearm
Dorsal hand (back of hand) - lateral hand, thumb and proximal 2nd-4th digits (not the tips of these fingers)

Question 23

Which cord and nerve roots does the ulnar nerve arise from?

Answer 23

Arises from the medial cord
C8 - T1 (occasionally C7)

Question 24

Which muscles does the ulnar nerve innervate?

Answer 24

1. Flexor carpi ulnaris
2. Ulnar half of the flexor digitorum profundus
3. Most of the intrinsic muscles of the hand which aren’t innervated by the median nerve. This includes
   - palmaris brevis
   - lumbricals
   - hypothenar
   - interossei muscles

Question 25

What is the sensory innervation of the ulnar nerve?

Answer 25

1. Palmar - medial 1.5 digits and adjacent palm 2. Dorsal - medial 1.5 digits and adjacent skin of the back of the hand

Question 26

Nerve root at which level is responsible for shoulder abduction?

Answer 26

1. movement = shoulder abduction 2. muscle = deltoid 3. nerve = axillary 4. cord = posterior cord 4. root = C5

Question 27

Nerve root at which level is responsible for elbow flexion?

Answer 27

1. movement = elbow flexion 2. muscle = biceps brachii 3. nerve = musculocutaneous 4. cord = lateral cord 5. root = C6

Question 28

Nerve root at which level is responsible for elbow extension?

Answer 28

1. movement = elbow extension 2. muscle = triceps brachii 3. nerve = radial 4. cord = posterior cord 5. root = C7

Question 29

Nerve root at which level is responsible for wrist extension?

Answer 29

1. movement = wrist extension 2. muscle = extensor carpi radialis 3. nerve = radial 4. cord = posterior cord 5. root = C7/8

Question 30

Nerve root at which level is responsible for wrist flexion?

Answer 30

1. movement = wrist flexion 2. muscle = flexor carpi ulnaris 3. nerve = ulnar 4. cord = medial cord 5. root = C7/8

Question 31

Nerve root at which level is responsible for finger flexion?

Answer 31

1. movement = finger flexion 2. muscle = FDS/FDP 3. nerve = median (+ ulnar) 4. cord = lateral and medial cords 5. root = C8

Question 32

Nerve root at which level is responsible for finger extension?

Answer 32

1. movement = finger extension 2. muscle = extensor digitorum 3. nerve = radial 4. cord = posterior cord 5. root = C8

Question 33

Nerve root at which level is responsible for finger abduction?

Answer 33

1. movement = finger abduction 2. muscle = dorsal interossei 3. nerve = ulnar 4. cord = medial cord 5. root = T1

Question 34

Lesions in which nerves can cause scapular winging?

Answer 34

most common - long thoracic nerve less common - accessory nerve rare - dorsal scapular nerve