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Flashcards in Ulnar Nerve Deck (43):
1

What is the ulnar nerve?

A major peripheral nerve of the upper limb

2

What are the spinal roots of the ulnar nerve?

C8-T1

3

What muscles does the ulnar nerve innervate?

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

4

What are the sensory functions of the ulnar nerve?

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

5

What is the ulnar nerve derived from?

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

6

What course does the ulnar nerve take?

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

7

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

It is easily palpable and vulnerable to injury

8

What does the ulnar nerve do in the forearm?

Pierces the two heads of the flexor carpi ulnaruis

9

Where does the ulnar nerve travel in the forearm?

Alongside the ulna

10

What branches arise from the ulnar nerve in the forearm?

Muscular branch
Palmar cutaneous branch 
Dorsal cutaneous branch

11

What does the muscular branch of the ulnar nerve do?

Innervates some muscles in the anterior compartment of the forearm

12

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

Innervates the skin of the medial half of the palm

13

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

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

14

Where does the ulnar nerve travel in the wrist?

Superficially, to the flexor retinaculum

15

How does the ulnar nerve enter the hand?

Via the ulnar canal (or Guyon’s canal)

16

How does the ulnar nerve terminate?

In the hand it gives rise to superficial and deep branches

17

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

Flexor carpi ulnaris 
Flexor digitorum profundus (medial half)

18

What does the flexor carpi ulnaris do?

Flexes the hand and adducts the hand at the wrist

19

What does the flexor digitorum profundus do?

Flexes the fingers

20

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

The median nerve

21

What does the deep branch of the ulnar nerve innervate?

The majority of the intrinsic hand muscles

22

What muscles in the hand does the ulnar nerve innervate?

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

23

What are the hypeothenar muscles?

A group of muscles associated with the little finger

24

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

The median nerve

25

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

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

26

Where do the palmar and dorsal cutaneous branches arise?

In the forearm

27

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

The skin of the medial half of the palm

28

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

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

29

Where does the superficial branch of the ulnar nerve arise?

In the hand

30

Where does the superficial branch of the ulnar nerve innervate?

The palmar surface of the medial one and a half fingers

31

Where is the ulnar nerve most susceptible to injury?

The elbow and wrist

32

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

At the medial epicondyle

33

How does ulnar nerve damage at the elbow commonly occur?

Fracture of the medial epicondyle

34

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

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

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

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

36

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

Patient cannot grip paper placed between fingers

37

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

Lacerations to the wrist

38

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

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

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

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

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

Patient cannot grip paper placed between fingers
For long-term cases, ‘ulnar claw’ develops

41

What does ulnar claw consist of?

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

42

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

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

43

When may flexion at the interphalangeal joints not be apparent?

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