Ulnar Nerve Flashcards

1
Q

What is the ulnar nerve?

A

A major peripheral nerve of the upper limb

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2
Q

What are the spinal roots of the ulnar nerve?

A

C8-T1

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3
Q

What muscles does the ulnar nerve innervate?

A

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

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4
Q

What are the sensory functions of the ulnar nerve?

A

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

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5
Q

What is the ulnar nerve derived from?

A

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

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6
Q

What course does the ulnar nerve take?

A

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

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7
Q

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

A

It is easily palpable and vulnerable to injury

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8
Q

What does the ulnar nerve do in the forearm?

A

Pierces the two heads of the flexor carpi ulnaruis

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9
Q

Where does the ulnar nerve travel in the forearm?

A

Alongside the ulna

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10
Q

What branches arise from the ulnar nerve in the forearm?

A

Muscular branch
Palmar cutaneous branch
Dorsal cutaneous branch

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11
Q

What does the muscular branch of the ulnar nerve do?

A

Innervates some muscles in the anterior compartment of the forearm

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12
Q

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

A

Innervates the skin of the medial half of the palm

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13
Q

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

A

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

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14
Q

Where does the ulnar nerve travel in the wrist?

A

Superficially, to the flexor retinaculum

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15
Q

How does the ulnar nerve enter the hand?

A

Via the ulnar canal (or Guyon’s canal)

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16
Q

How does the ulnar nerve terminate?

A

In the hand it gives rise to superficial and deep branches

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17
Q

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

A

Flexor carpi ulnaris

Flexor digitorum profundus (medial half)

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18
Q

What does the flexor carpi ulnaris do?

A

Flexes the hand and adducts the hand at the wrist

19
Q

What does the flexor digitorum profundus do?

A

Flexes the fingers

20
Q

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

A

The median nerve

21
Q

What does the deep branch of the ulnar nerve innervate?

A

The majority of the intrinsic hand muscles

22
Q

What muscles in the hand does the ulnar nerve innervate?

A

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

23
Q

What are the hypeothenar muscles?

A

A group of muscles associated with the little finger

24
Q

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

A

The median nerve

25
Q

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

A

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

26
Q

Where do the palmar and dorsal cutaneous branches arise?

A

In the forearm

27
Q

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

A

The skin of the medial half of the palm

28
Q

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

A

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

29
Q

Where does the superficial branch of the ulnar nerve arise?

A

In the hand

30
Q

Where does the superficial branch of the ulnar nerve innervate?

A

The palmar surface of the medial one and a half fingers

31
Q

Where is the ulnar nerve most susceptible to injury?

A

The elbow and wrist

32
Q

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

A

At the medial epicondyle

33
Q

How does ulnar nerve damage at the elbow commonly occur?

A

Fracture of the medial epicondyle

34
Q

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

A

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

35
Q

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

A

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

36
Q

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

A

Patient cannot grip paper placed between fingers

37
Q

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

A

Lacerations to the wrist

38
Q

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

A

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.

39
Q

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

A

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

40
Q

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

A

Patient cannot grip paper placed between fingers

For long-term cases, ‘ulnar claw’ develops

41
Q

What does ulnar claw consist of?

A

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

42
Q

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

A

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

43
Q

When may flexion at the interphalangeal joints not be apparent?

A

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