Upper Extremity Nerves EC

Question 1

Axillary nerve (roots, typical injury, sign, muscles innervated)

Answer 1

C5-6

Fractures surgical neck of humerus
Dislocation of humeral head

Atrophied deltoid

Deltoid, Triceps longhead, teres minor

Question 2

Radial nerve (roots, typical injury, sign, muscles innervated)

Answer 2

C5-T1

Fractures midshaft humerus
“Saturday Night palsy”/Incorrect use of crutches

Wrist drop

BEST: Brachioradialis, Extensors, Supinator, Triceps

Question 3

Median nerve (roots, typical injury, sign, muscles innervated)

Answer 3

C5-T1

Fracture of supracondylar humerus

Impaired opposition of thumb, lateral finger flexion, and wrist flexion
“Ape hand” and “Pope’s blessing”

Forearm: flexors (minus carpi ulnaris and ulnar 1/2 of digitorum profundus)
Hand: Thenar muscles and 1st 2 lumbricals (“MED-LOAF”)

Question 4

Ulnar nerve (roots, typical injury, sign, muscles innervated)

Answer 4

C8, T1

Fracture of medial epicondyle of humerus (funny bone)

Impaired medial finger flexion and wrist flexion
Radial deviation of wrist upon flexion

Forearm: flexor carpi ulnaris + 1/2 digitorum profundus
Hand: all but MED-LOAF

Question 5

Musculocutaneous nerve (roots, typical injury, sign, muscles innervated)

Answer 5

C5-C7

Upper trunk compression

Impaired flexion at elbow

BBC - Brachialis, Biceps, Coracobrachialis

Question 6

Limb adducted, medially rotated, and forearm pronated (lesion and common cause)

Answer 6

Damage to C5-C6 roots (Erbs palsy)

Often seen in infants following trauma during delivery

Question 7

Atrophy of the thenar and hypothenar eminences, Atrophy of the interosseous muscles, Sensory deficits on the medial side of the forearm and hand, Disappearance of the radial pulse upon moving head toward ipsilateral side

Answer 7

Embryologic defect in C8-T1 or a cervical rib compressing subclavian artery and inferior trunk

Klumpke’s palsy/Thoracic outlet syndrome

Question 8

Inability to extend 4th and 5th digits when trying to open hand

Answer 8

Ulnar claw

Distal ulnar nerve lesion (ie hook of hamate) leads to loss of medial lumbrical function

Question 9

2nd and 3rd digits clawed upon attempted finger extension.

Answer 9

Median claw

Carpel tunnel or dislocated lunate
Distal median nerve lesion leads to loss of lateral lumbrical function

Question 10

Loss of function of all lumbricals, finger flexers. Clawing of all digits

Answer 10

Klumpke’s total claw

C8-T1 lesion

Question 11

What does the dorsal scapular nerve innervate?

Answer 11

Rhomboids

Question 12

What does the long thoracic nerve innervate?

Answer 12

Serratus anteroir

Question 13

What does the suprascapular nerve innervate?

Answer 13

Supraspinatus and Infraspinatus

Question 14

What does the lateral pectoral nerve innervate?

Answer 14

Pectoralis major

Question 15

What does the medial pectoral nerve innervate?

Answer 15

Pectoralis major and minor

Question 16

What does the upper subscapular nerve innervate?

Answer 16

Subscaularis

Question 17

What does the thoracodorsal nerve innervate?

Answer 17

Latissimus dorsi

Question 18

What does the lower subscapular nerve innervate?

Answer 18

Subscapularis and Teres major

Question 19

What does the medial branch of the cutaneous nerve innervate?

Answer 19

Skin of the medial forearm

Question 20

What does the medial antebrachial cutaneous nerve innervate?

Answer 20

Skin of medial forearm