Ulnar Nerve

Question 1

What is the ulnar nerve?

Answer 1

A major peripheral nerve of the upper limb

Question 2

What are the spinal roots of the ulnar nerve?

Answer 2

C8-T1

Question 3

What muscles does the ulnar nerve innervate?

Answer 3

The muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum produndus

Question 4

What are the sensory functions of the ulnar nerve?

Answer 4

Innervates the anterior and posterior surfaces of the medial one and a half fingers, and associated palm area

Question 5

What is the ulnar nerve derived from?

Answer 5

The brachial plexus- is a continuation of the medial cord, containing fibres from spinal roots C8 and T1

Question 6

What course does the ulnar nerve take?

Answer 6

After arising from the brachial plexus, it descends down the medial side of the upper arm. At the elbow, it passes posterior to the medial epicondyle, entering the forearm

Question 7

What can be said of the ulnar nerve as it passes posterior to the medial epicondyle?

Answer 7

It is easily palpable and vulnerable to injury

Question 8

What does the ulnar nerve do in the forearm?

Answer 8

Pierces the two heads of the flexor carpi ulnaruis

Question 9

Where does the ulnar nerve travel in the forearm?

Answer 9

Alongside the ulna

Question 10

What branches arise from the ulnar nerve in the forearm?

Answer 10

Muscular branch
Palmar cutaneous branch
Dorsal cutaneous branch

Question 11

What does the muscular branch of the ulnar nerve do?

Answer 11

Innervates some muscles in the anterior compartment of the forearm

Question 12

What does the palmar cutaneous branch of the ulnar nerve do?

Answer 12

Innervates the skin of the medial half of the palm

Question 13

What does the dorsal cutaneous branch of the ulnar nerve do?

Answer 13

Innervates the skin of the medial 1 and a 1/2 fingers, and the associated palm area

Question 14

Where does the ulnar nerve travel in the wrist?

Answer 14

Superficially, to the flexor retinaculum

Question 15

How does the ulnar nerve enter the hand?

Answer 15

Via the ulnar canal (or Guyon’s canal)

Question 16

How does the ulnar nerve terminate?

Answer 16

In the hand it gives rise to superficial and deep branches

Question 17

What muscles does the muscular branch of the ulnar nerve supply in the anterior forearm?

Answer 17

Flexor carpi ulnaris

Flexor digitorum profundus (medial half)

Question 18

What does the flexor carpi ulnaris do?

Answer 18

Flexes the hand and adducts the hand at the wrist

Question 19

What does the flexor digitorum profundus do?

Answer 19

Flexes the fingers

Question 20

What are the muscles in the anterior forearm that aren’t innervated by the ulnar nerve innervated by?

Answer 20

The median nerve

Question 21

What does the deep branch of the ulnar nerve innervate?

Answer 21

The majority of the intrinsic hand muscles

Question 22

What muscles in the hand does the ulnar nerve innervate?

Answer 22

The hypothenar muscles
Medial two lumbricals
Adductor pollicis
Interossei of the hand

Question 23

What are the hypeothenar muscles?

Answer 23

A group of muscles associated with the little finger

Question 24

What are the muscles in the hand that aren’t innervated by the ulnar nerve innervated by?

Answer 24

The median nerve

Question 25

What is responsible for the cutaneous innervation function of the ulnar nerve?

Answer 25

Three branches, the palmar cutaneous branch, dorsal cutaneous branch, and the superficial branch

Question 26

Where do the palmar and dorsal cutaneous branches arise?

Answer 26

In the forearm

Question 27

Where does the palmar cutaneous branch of the ulnar nerve innervate?

Answer 27

The skin of the medial half of the palm

Question 28

Where does the dorsal cutaneous branch of the ulnar nerve innervate?

Answer 28

The skin of the medial one and a half fingers, and the associated palm area

Question 29

Where does the superficial branch of the ulnar nerve arise?

Answer 29

In the hand

Question 30

Where does the superficial branch of the ulnar nerve innervate?

Answer 30

The palmar surface of the medial one and a half fingers

Question 31

Where is the ulnar nerve most susceptible to injury?

Answer 31

The elbow and wrist

Question 32

Where is the ulnar nerve most vulnerable to injury at the elbow?

Answer 32

At the medial epicondyle

Question 33

How does ulnar nerve damage at the elbow commonly occur?

Answer 33

Fracture of the medial epicondyle

Question 34

How are motor functions affected by ulnar nerve damage at the elbow?

Answer 34

Flexor carpi ulnaris and medial half of flexor digitorum profundus paralysed.
Flexion of the wrist can still occur, but is accompanied by abudction
Interossei are paralysed, so abduction and adduction of fingers cannot occur
Movement of little and ring fingers is greatly reduced, due to paralysis of the medial two lumbricals

Question 35

How are sensory functions affected by ulnar nerve damage at the elbow?

Answer 35

All sensory branches are affected, so loss of sensation over the areas that the ulnar nerve innervates

Question 36

What are the characteristic signs of ulnar nerve damage at the elbow?

Answer 36

Patient cannot grip paper placed between fingers

Question 37

How does damage to the ulnar nerve at the wrist commonly occur?

Answer 37

Lacerations to the wrist

Question 38

How does damage to the ulnar nerve at the wrist affect motor function?

Answer 38

The interossei are paralysed, so abduction and adduction of the fingers cannot occur.
Movement of the little and ring fingers is greated reduced, due to paralysis of the medial two lumbricas.

Question 39

How does damage to the ulnar nerve at the wrist affect sensory function?

Answer 39

The palmar branch and superficial branch are usually severed (but the dorsal branch unaffected)
Sensory loss over palmar side of medial one and a half fingers

Question 40

What are the characteristic signs of ulnar nerve damage at the wrist?

Answer 40

Patient cannot grip paper placed between fingers

For long-term cases, ‘ulnar claw’ develops

Question 41

What does ulnar claw consist of?

Answer 41

Hyper-extension of the metacarpophalangeal joints of the little and ring fingers
Flexion at the interphalangeal joints

Question 42

Why does the ulnar claw have hyper-extension of the metacarpophalangeal joints of the little and ring fingers?

Answer 42

Because of paralysis of the medial two lumbricals, and the now unopposed action of the extensor muscles

Question 43

When may flexion at the interphalangeal joints not be apparent?

Answer 43

If the lesion has occurred close to the elbow, as the flexor digitorum profundus will be paralysed