Upper Extremity Nerves

Which cord of the brachial plexus gives rise to the axillary nerve?

posterior cord

Which nerve roots contribute to the axillary nerve?

C5-C6

Which muscles receive motor innervation from the axillary nerve?

Teres minor

Deltoid

The primary action of the teres minor muscle is which of the following?

shoulder external rotation, extension, abduction, horizontal abduction

The deltoid muscle is composed of which distinct portions?

Anterior deltoid

Posterior deltoid

Acromial fibers

What is the primary action of the anterior deltoid muscle?

Shoulder internal rotation, flexion, horizontal adduction

What is the primary action of the posterior deltoid muscle?

Shoulder external rotation, extension, horizontal abduction

What is the primary action of the acromial fibers?

Powerful shoulder abductors

The axillary nerve continues distally as which cutaneous nerve, and what is its sensory distribution?

upper lateral cutaneous nerve of arm and supplies the skin covering the lower half of deltoid and upper part of long head of triceps

Injury to the axillary nerve is most commonly associated with which of the following mechanisms?

Dislocation of shoulder

Fracture of surgical neck of humerus

Injury to the axillary nerve would most likely result in which of the following deficits?

square shoulder from deltoid muscle atrophy

sensory loss over lower half of deltoid

The radial nerve is a branch of which part of the brachial plexus?

branch of posterior cord

Which spinal nerve roots contribute to the radial nerve?

C5-C8, T1

Through which anatomical space does the radial nerve exit the axilla?

triangular interval and travels down humerus in radial groove

At the level of the elbow, the radial nerve passes anterior to the lateral epicondyle and travels under the origin of a specific muscle before dividing into superficial and deep branches. Which muscle does the radial nerve pass under at this location?

Extensor carpi radialis brevis

Which muscles receive motor innervation from the radial nerve?

triceps

anconeus

brachioradialis

supinator

extensor carpi radialis longus

extensor carpi radialis brevis

extensor carpi ulnaris

extensor digitorum

extensor digiti minimi

extensor pollicis longus

extensor pollicis brevis

extensor indicis

abductor pollicis longus

What is the primary action of the triceps brachii muscle?

elbow extension

What is the primary action of the anconeus muscle?

weak elbow extensor

What is the primary action of the brachioradialis muscle?

elbow flexion

What is the primary action of the supinator muscle?

supination of forearm

What is the primary action of the extensor carpi radialis longus muscle?

wrist extension

radial deviation

What is the primary action of the extensor carpi radialis brevis muscle?

wrist extension

radial deviation

What is the primary action of the extensor carpi ulnaris muscle?

wrist extension

ulnar deviation

What is the primary action of the extensor digitorum muscle?

2-5th digits extension at MCP, IP, and wrist

What is the primary action of the extensor digiti minimi muscle?

5th digit extension at MCP and IP

What is the primary action of the extensor pollicis longus muscle?

1st digit extension at CMC and IP

What is the primary action of the extensor pollicis brevis muscle?

1st digit extension at MCP and IP

What is the primary action of the extensor indicis muscle?

2nd digit extension

wrist extension

What is the primary action of the abductor pollicis longus muscle?

1st digit abduction

extension at CMC joint

The radial nerve provides sensory innervation through:

Lower lateral cutaneous nerve of the arm

posterior cutaneous nerve of the arm

posterior cutaneous nerve of the forearm

superficial branch

The lower lateral cutaneous nerve of the arm provides sensory innervation to which region?

skin of lower half of lateral side of arm

The posterior cutaneous nerve of the arm provides sensory innervation to which region?

skin of back of the arm

The posterior cutaneous nerve of the forearm provides sensory innervation to which region?

skin of the back of forearm

The superficial branch provides sensory innervation to which region?

skin of lateral half of dorsum of hand

lateral two and half digits including thumb

Injury to the radial nerve most commonly occurs in which locations?

axilla

musculospiral groove

around radial neck

Which of the following best describes radial tunnel syndrome?

tenderness in the extensor muscle mass of the forearm (distal to lateral epicondyle)

long finger extension test reproduces pain

Which of the following are characteristic conditions or clinical presentations associated with radial nerve injury?

radial tunnel syndrome

posterior interosseous nerve syndrome

wrist drop

The ulnar nerve is a branch of which cord of the brachial plexus?

medial cord

Which spinal nerve roots contribute to the ulnar nerve?

C7-T1 (main contribution from C8-T1)

Through which anatomical regions does the ulnar nerve travel along its course?

Passes behind medial epicondyle

pierces the flexor carpi ulnaris to enter forearm

superficial to flexor retinaculum

enters hand via Guyon's canal/tunnel

Which muscles receive motor innervation from the ulnar nerve?

Dorsal interossei

palmar interossei

adductor pollicis

opponens digiti minimi

flexor digiti minimi

abductor digiti minimi

flexor pollicis brevis

flexor digitorum profundus (medial half)

flexor carpi ulnaris

lumbricals (3-4)

What is the primary action of the dorsal interossei muscles of the hand?

abduction of 2-4th digits away from middle finger

Which mnemonic is commonly used to remember the action of the dorsal interossei muscle?

DAB

What is the primary action of the palmar interossei muscles of the hand?

adduction of 2nd, 4th, 5th digits towards middle finger

flexion of digit at MCP

extension at IP

Which mnemonic is commonly used to remember the action of the palmar interossei muscles?

PAD

What is the primary action of the adductor pollicis muscle?

adduction of thumb

What is the primary action of the oppenens digiti minimi muscle?

flexion of 5th metacarpal

lateral rotation producing opposition

What is the primary action of the flexor digiti minimi muscle?

flexion of little finger

What is the primary action of the abductor digiti minimi muscle?

abduction of little finger at MCP joint

What is the primary action of the flexor pollicis brevis muscle?

flexion of thumb

What is the primary action of the flexor digitorum profundus (medial half)?

flexion of DIP

What is the secondary action of the flexor digitorum profundus (medial half)?

flexion of joints of digits, finger, and wrist

What is the primary action of the flexor carpi ulnaris muscle?

wrist flexion

ulnar deviation

What is the primary action of the lumbricals?

flexion at MCP

extension at IP

Which of the following branches contribute to the sensory distribution of the ulnar nerve?

palmar cutaneous branch

dorsal cutaneous branch

superficial branch

The palmar cutaneous branch of the ulnar nerve provides sensory innervation to which area?

supplies medial 1/2 of palm

The dorsal cutaneous branch of the ulnar nerve provides sensory innervation to which area?

supplies skin of dorsal aspect of medial one and half fingers

The superficial branch of the ulnar nerve provides sensory innervation to which area?

supplies 1/2 of 4th and 5th digit

An ulnar nerve lesion can result in several clinical conditions. Which of the following are characteristic presentations of ulnar nerve injury?

cubital tunnel syndrome

Guyon's canal syndrome

ulnar claw hand

Which of the following best describes the characteristic presentation of ulnar claw hand?

hyperextension at the MCP joints and flexion at the IP joints of the 4th and 5th digits due to weakness of lumbricals and interossei

Which of the following best describes Guyon's canal syndrome?

sensory changes and progressive weakness of muscles innervated distal to the site

Cubital tunnel syndrome is caused by compression of which nerve at the elbow?

ulnar nerve

Which of the following muscles would most likely be paralyzed in cubital tunnel syndrome?

flexor carpi ulnaris

flexor digitorum profundus (ulnar half)

hypothenar eminence

interossei

3rd and 4th lumbricals

A patient with cubital tunnel syndrome may present with:

inability to grip paper between fingers

sensory deficits in the 4th and 5th fingers

The median nerve is a branch of which cord(s) of the brachial plexus?

medial and lateral cords

Which spinal nerve roots contribute to the median nerve?

C5-C8, T1

Through which anatomical regions does the median nerve travel from the brachial plexus to the hand?

Descends lateral to brachial artery

enters forearm between two heads of pronator teres muscle

enters hand via carpal tunnel

Which muscles receive motor innervation from the median nerve?

flexor digitorum profundus (radial half)

flexor pollicis longus

pronator quadratus

abductor pollicis brevis

pronator teres

oppenens pollicis

palmaris longus

lumbricals 1-2

flexor carpi radialis

flexor digitorum superficialis

flexor pollicis brevis

What is the primary action of the flexor digitorum profundus muscle?

flexion of DIP

What is the secondary action of the flexor digitorum profundus muscle?

flexion of joints of digits, finger, and wrist

What is the primary action of the flexor pollicis longus muscle?

flexion of distal phalanx of thumb

What is the primary action of the pronator quadratus muscle?

pronation of forearm

What is the primary action of the abductor pollicis brevis muscle?

abduction of thumb at MCP and CMC joint

What is the primary action of the pronator teres muscle?

pronation of forearm

elbow flexion

What is the primary action of the opponens pollicis muscle?

opposition of thumb

What is the primary action of the palmaris longus muscle?

flexion of wrist

What is the primary action of the lumbricals 1-2?

flexion of MCP

extension of IP

What is the primary action of the flexor carpi radialis muscle?

wrist flexion

radial deviation

What is the primary action of the flexor digitorum superficialis muscle?

flexion of PIP joint

Which branches of the median nerve provide sensory innervation to the hand?

palmar cutaneous branch

palmar digital branches

The palmar cutaneous branch of the median nerve provides sensory innervation to which area of the hand?

skin of lateral two thirds of palm

The palmar digital branches of the median nerve provides sensory innervation to which area of the hand?

supplies dorsal tips of 1-3 fingers

palmar skin of lateral three and half fingers

Which of the following are characteristic presentations of median nerve injury?

pronator teres syndrome

carpal tunnel syndrome

ape hand deformity

Hypertrophy of the pronator teres muscle can compress the median nerve. Which of the following clinical findings would most likely be present?

Pronator teres normal

weakness in other median innnervated muscles

sensory deficits in the median nerve distribution

Compression of the median nerve under the flexor retinaculum at the wrist is most consistent with which condition?

carpal tunnel syndrome

Wasting of the thenar eminence is most likely caused by injury to which nerve?

median nerve

A patient presents with atrophy of the thenar eminence and loss of thumb opposition, resulting in a flattened appearance of the thumb in the same plane as the palm. This presentation is most consistent with:

ape hand deformity

The musculocutaneous nerve is a branch of which cord of the brachial plexus?

lateral cord

Which spinal nerve roots contribute to the musculocutaneous nerve?

C5-C7

Which muscles receive motor innervation from the musculocutaneous nerve?

biceps

brachialis

coracobrachialis

What is the primary action of the biceps brachii muscle?

elbow flexion

forearm supination

flexion of arm

What is the primary action of the brachialis muscle?

elbow flexion

What is the primary action of the coracobrachialis muscle?

flexion of arm

Which of the following nerves provides the sensory innervation for the musculocutaneous nerve?

lateral cutaneous nerve of the forearm

The lateral cutaneous nerve of the forearm, a branch of the musculocutaneous nerve, provides sensory innervation to which area?

lateral forearm

The suprascapular nerve arises from which part of the brachial plexus?

upper trunk

Which spinal nerve roots contribute to the suprascapular nerve?

C5-C6

Which muscles receive motor innervation from the suprascapular nerve?

infraspinatus

supraspinatus

What is the primary action of the infraspinatus muscle?

lateral rotation and abduction of arm

What is the primary action of the supraspinatus muscle?

shoulder abduction up to 15 degrees