Innervation of Upper Limb_MSB Flashcards Preview

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Flashcards in Innervation of Upper Limb_MSB Deck (93):
1

What are the roots of the Musculocutaneous Nerve?

C5 - C7

2

What is the muscles that is allowed motor function by the Musculocutaneous nerve?

Biceps Brachii
Brachialis
Coracobrachialis

3

What is the sensory function of the musculocutaneous nerve?

1) Lateral cutaneous branch of forearm
2) innervates lateral 1/2 of anterior forearm
3) Innervates lateral position of posterior forearm

4

What is the Anatomical course of the Musculocutaneous Nerve?

1) Arises from the lateral cord of the brachial plexus
2) Exits the Axilla
3) Pierces Coracobrachialis near its insertion
4) Passes down the arm anterior to Brachialis and deep to Biceps Brachii innervating them
5) Emerges lateral to the biceps tendon to continue into the forearm as the Lateral Cutaneous Nerve of Forearm
6) The lateral cutaneous nerve of forearm innervates the skin of the lateral aspect of the forearm

5

Is Musculocutaneous Nerve injury common?

Relatively uncommon because it is protected within the axilla

6

What is the most common Musculocutaneous Nerve injury?

Stab wound to the axilla

7

What happens to the motor functions when there is a Musculocutaneous Nerve Injury?

The BBC muscles become paralysed

8

What happens when the BBC muscles become paralysed during a musculocutaneous nerve injury?

1) Flexion at the shoulder is weakened but can still occur due to pectoralis major
2) Flexion at the elbow is affected but can still occur due to brachioradialis
3) Supination is greatly weakened but can still be produced by the supinator muscle

9

What happens to the sensory functions when there is a Musculocutaneous Nerve injury?

Loss of sensation over the lateral side of the forearm

10

What are the roots of the median nerve?

C6 - T1

11

What is the muscles that have motor function by the median nerve?

1) Forearm Flexors
2) Thenar muscle

12

What is the sensory function of the Median nerve?

1) Palmar cutaneous nerve innervates lateral palm
2) Digital cutaneous nerve innervates lateral 3 1/2 fingers on palmar hand

13

What is the Anatomical course of the Median Nerve?

1) Arises from Medial and Lateral cords of brachial plexus
2) Leaves the axilla
3) Descends in the arm initially lateral to the brachial artery. Halfway down the arm it crosses over the brachial artery to become medially situated
4) Enters anterior forearm via the cubital fossa
5) In the forearm is located between the flexor digitorum profundus and flexor digitorum superficialis
6) Innervates superficial and intermediate layers of anterior forearm
7) Give rise to 2 major branches in the forearm (Anterior interosseous nerve and Palmar cutaneous nerve)
8) Enters the hand via the carpal tunnel and terminates by dividing into 2 branches (Recurrent branch of median nerve and Palmar digital branch)

14

What is the superficial layer that is innervated by the median nerve?

1) Pronator Teres
2) Flexor Carpi Radialis
3) Palmaris Longus

15

What is the intermediate layer that is innervated by the median nerve?

1) Flexor digitorum superficialis

16

What does the Anterior interosseous nerve do?

Supplies the deep muscles in the anterior foreram

17

What are the 2 branches in the forearm that the median nerve gives rise to?

1) Anterior Interosseous Nerve
2) Palmar Cutaneous Nerve

18

What is the deep layer that is innervated by the Anterior Interosseous nerve?

1) Flexor Pollicis Longus
2) Pronator Quadratus
3) Lateral half of the flexor digitorum profundus

19

What does the Palmar Cutaneous Nerve do?

Innnervates the skin of the lateral palm

20

What are the 2 branches that the median nerve terminates by?

1) Recurrent branch of median nerve
2) Palmar digital branch

21

What does the recurrent branch of the median nerve do>

Innervates the thenar muscles

22

What does the Palmar digital branch do?

Innervates:
1) lateral two lumbricals
2) Palmar surface and fingertips of the lateral three and half digits

23

What is a median nerve injury?

Carpal Tunnel Syndrome

24

What is Carpal Tunnel Syndrome?

The thenar eminence becomes wasted due to atrophy of the thenar muscles

25

How do you detect irritated nerves (test for Carpel Tunnel syndrome)?

Tinel's sign

26

How is Tinel's sign performed?

It is performed by lightly tapping (percussing) over the nerve to elicit a sensation of tingling or "pins and needles" in the distribution of the nerve.

27

What are the different ways that the Median Nerve can be injured?

1) Damaged at elbow via Supracondylar fracture of humerus
2) Damaged at wrist via laceration just proximal to the flexor retinaculum.

28

What happens to the motor function when there is damage at elbow via Supracondylar fracture of humerus resulting in Median nerve injury?

The flexors and pronators of forearm are paralysed (except flexor carpi ulnas and medial half of flexor digitorum profundus)

29

What happens when the flexors and pronators of forearm become paralysed during a median nerve injury?

1) The forearm is constantly supinated and flexion is weak
2) Flexion cannot occur at the thumb as both longus and brevis muscles are paralysed
3) Flexion at the MCP joints and extension at IP joints of the index & middle fingers is affected due to paralysis of the lateral 2 lumbricals

30

What happens to the sensory function when there is damage at elbow via Supracondylar fracture of humerus resulting in Median nerve injury?

Lack of sensation over the areas that the median nerve inneravtes

31

What is an indication of a median nerve injury?

Hand of Benediction
- If a patient tries to make a fist, only the ring and little fingers can flex completely.
- This results in a characteristic shape of the hand

32

What happens to the motor function when there is damage at wrist via laceration just proximal to the flexor retinaculum resulting in Median nerve injury?

Thenar muscles are paralysed and lateral two lumbricals.

33

What happens when the thenar muscles and lateral two lumbricals become paralysed during median nerve injury?

Opposition of the thumb and flexion of the index and middle fingers is affected

34

What happens to the sensory function when there is damage at wrist via laceration just proximal to the flexor retinaculum resulting in Median nerve injury?

Same as an injury at the elbow
(Lack of sensation over the areas that the median nerve innervates)

35

What are the roots of the Ulnar Nerve?

C8 and T1

36

What is the muscles that have motor function by the ulnar nerve?

1) Muscles of the hand (except thenar muscles & 2 lateral lumbricals),
2) flexor carpi ulnaris
3) Medial 1/2 flexor digitorum profundus

37

What is the sensory function of the ulnar nerve?

Innervates anterior and posterior surfaces of medial 1 1/2 digits and palm

38

What is the anatomical course of the Ulnar Nerve?

1) Arises from the medial cord of the brachial plexus
2) Descends along medial side of the upper arm
3) At the elbow, it passes posterior to the medial epicondyle to enter the forearm.
4) In the forearm, the ulnar nerve pierces the two heads of the flexor carpi ulnas and travels alongside the ulna.
5) Three branches arise in the forearm (Muscular branch, palmar cutaneous branch, dorsal cutaneous branch)
6) At the wrist, the ulnar nerve travels superficially to the flexor retinaculum
7) Enters the hand via the ulnar canal (or Guyon's canal)
8) Give rise to superficial and deep branch
9) The majority of the intrinsic hand muscles are innervated by the deep branch of the ulnar nerve

39

What location is easily palpable & vulnerable to injury?

At the elbow, it passes posterior to the medial epicondyle to enter the forearm.

40

What are the three branches that arise in the forearm by the ulnar nerve?

1) Muscular branch
2) Palmar Cutaneous Branch
3) Dorsal Cutaneous Branch

41

What does the Muscular branch do?

Innervates:
1) Flexor digitorum profundus (medial half)
2) Flexor carpi ulnaris in anterior forearm

42

What does the Palmar Cutaneous branch do?

Innervates skin of the medial half to the palm

43

What does the Dorsal Cutaneous branch do?

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

44

What are the intrinsic hand muscles innervated by the deep branch of the ulnar nerve?

1) Hypothenar muscle
2) Medial 2 lumbricals
3) Adductor pollicis
4) Interossei

45

What does the superficial branch do?

Innervates palmar surface of medial one and a half fingers

46

What are the two ways that leads to ulnar nerve injury?

1) Damaged at elbow via fracture of the medial epicondyle
2) Damaged at wrist via laceration

47

What happens to motor function when elbow is damaged via fracture of the medial epicondyle leading to ulnar nerve injury?

1) Flexor Carpi Ulnaris and Medial half of Flexor Digitorum profundus paralysed
2) Interossei paralysed
3) Medial two lumbricals paralysed

48

What happens when the Interossei is paralysed during the ulnar nerve injury?

Abduction and adduction of the fingers cannot occur

49

What happens when the medial two lumbricals are paralysed during ulnar nerve injury?

Movement of the little and ring fingers is greatly reduced

50

What happens to sensory functions when elbow is damaged via fracture of the medial epicondyle leading to ulnar nerve injury?

All sensory branches are affected so there will be a loss of sensation over the areas that the ulnar nerve innervates

51

What happens to the motor functions when the wrist is damaged via laceration leading to ulnar nerve injury?

1) The two muscles in the forearm are unaffected
2) Interossei paralysed
3) Paralysis of the medial two lumbricals

52

How does the Ulnar Claw form?

Ulnar nerve lesion at the wrist, deformity evident at rest

53

What happens during Ulnar Claw?

1) Lumbricals to digits 4 & 5 are paralysed
2) Loss of flexion at MCP joints
3) Loss of extension of IP joints

54

What does the Ulnar Claw lead to?

1) Hyperextension of MCP joints - unopposed Extensor Digitorum
2) Flexion of IP joints
- unopposed Flexor Digitorum Superficialis & Profundus

55

What is Guyon’s Canal Syndrome / Handlebar palsy caused by?

caused by entrapment of the ulnar nerve in the Guyon canal as it passes through the wrist

56

What is the symptom of Guyon's canal syndrome/ Handlebar palsy?

Symptoms usually begin with a feeling of pins and needles in the ring and little fingers before progressing to a loss of sensation and/or impaired motor function of the intrinsic muscles of the hand which are innervated by the ulnar nerve

57

Who does the Guyon's Canal Syndrom/Handlebar Palsy occur most in?

Cyclist due to prolonged pressure on the Guyon canal

58

What are the roots of the Radial Nerve?

C5 - T1

59

What is the muscles that have motor function by the Radial nerve?

1) Triceps brachii
2) Forearm extensors

60

What are the sensory functions by the Radial Nerve?

Innervates:
1) posterior aspect of arm and forearm
2) posterior and lateral aspects of hand

61

What is the Anatomical Course of the Radial Nerve?

1) Arises from posterior cord of the brachial plexus
2) Exits the axilla inferiorly supplying the long and medial heads of the triceps brachii
3) Descends in the arm travelling within the radial groove
4) As it descends, it wraps around the humerus laterally & supplies the lateral head of the triceps brachii
5) Entering the forearm, the radial nerve passes anteriorly over the lateral epicondyle and through the cubital fossa
6) Divides into superficial and deep branches

62

What does the deep branch do?

1) Control motor function
2) Innervates most of the muscles in the posterior compartment of the forearm

63

When is it termed posterior interosseous nerve?

When the deep branch penetrates the supinator muscles

64

What does the superficial branch do?

1) Control sensory function
2) Contributes to the cutaneous innervation of the hand and fingers

65

What are the cubital fossa contents (from lateral to medial)?

"Really Need Booze To Be At My Nicest"
Radial Nerve
Biceps Tendon
Brachial Artery
Median Nerve

66

What is the Anatomical course of the Radial Nerve?

- 4 branches of the radial nerve provide cutaneous innervation to skin of the upper limb
- Three of these branches arise in the upper arm
- Fourth branch is a terminal division of the radial nerve

67

What are the three branches that arise in the upper arm by the Radial nerve?

1) Lower lateral cutaneous nerve of arm
2) Posterior cutaneous nerve of arm
3) Posterior cutaneous nerve of forearm

68

What is the fourth branch that is the terminal division of the radial nerve

Superficial branch

69

What does the Lower Lateral Cutaneous nerve of arm innervate?

Lateral aspect of the upper arm below the deltoid muscle

70

What does the Posterior Cutaneous Nerve of arm innervate?

Posterior surface of the upper arm

71

What does the Posterior Cutaneous Nerve of forearm innervate?

A strip of skin down the middle of the posterior forearm.

72

What does the Superficial branch innervate?

Dorsal surface of the lateral three and half digits and associated palm area.

73

What are the different causes of a Radial Nerve injury?

1) Damaged within axilla region via shoulder dislocation
2) Proximal humeral fracture
3) Excess pressure on the nerve within axilla (e.g. axillary crutches)
4) Damaged within radial groove via fracture of humeral shaft

74

What happens to the motor function when there is a radial nerve injury due to damage within axilla religion, proximal humeral fracture or excess pressure on the nerve within axilla?

Triceps Brachii and Posterior Forearm muscles affected

75

What happens when Triceps Brachii and Posterior Forearm muscles is affected due to radial nerve injury?

1) Patient is unable to extend at the forearm, wrist and fingers
2) Unopposed flexion of wrist occurs known as wrist drop

76

What happens to the sensory function when there is a radial nerve injury due to damage within axilla religion, proximal humeral fracture or excess pressure on the nerve within axilla?

All four cutaneous branches of the radial nerve are affected

77

What happens when all four cutaneous branches of the radial nerve are affected due to a radial nerve injury?

Loss of sensation over:
1) the lateral and posterior upper arm
2) Posterior forearm
3) Dorsal surface of the lateral three and a half digits

78

Name the condition that is radial nerve injury due to compression of Axilla?

Saturday Night Palsy/Crutch Palsy

79

What is wrist drop?

Unopposed flexion of wrist

80

How does Saturday Night Palsy/Crutch Palsy happen?

Compression of nerve in axilla or upper arm in patient sleeping with arm over chair back, edge of bed etc. or by crutch

81

What happens to motor functions when there is a radial nerve injury due to damage within radial groove via fracture of humeral shaft?

1) Triceps brachii is weakened but not paralysed as branches to long and medial heads of the triceps arise proximal to the radial groove.
2) Extensor muscles of the posterior forearm are paralysed & wrist drop occurs

82

What happens to sensory functions when there is a radial nerve injury due to damage within radial groove via fracture of humeral shaft?

1) Cutaneous branches to the arm and forearm have already arisen.
2) Superficial branch of radial nerve will be damaged

83

What happens when Superficial branch of radial nerve will be damaged?

Sensory loss on the dorsal surface of the lateral three and half digits and palm area.

84

What are the roots of the Axillary Nerve?

C5, C6

85

What are the muscles that have motor function due to the Axillary Nerve?

1) Teres Minor
2) Deltoid

86

What are the sensory function by the Axillary Nerve?

1) Superior lateral cutaneous nerve of arm innervates inferior region of the deltoid (regimental badge area)

87

What is the Anatomical Course of the Axillary Nerve?

1) Arises from posterior cord of the brachial plexus
2) Descends to the inferior border of the Subscapularis muscle and exits the axilla posteriorly via the quadrangular space accompanied by the posterior circumflex humeral artery
3) In the posterior scapular region, the axillary nerve terminates by dividing into two branches: posterior and anterior terminal branch
4) The axillary nerve also provides articular branches to the shoulder joint
5) after the posterior terminal branch of the axillary nerve has innervated the teres minor, it continues as the upper lateral cutaneous nerve of the arm
6) This nerve innervates the skin over the inferior portion of the deltoid called the 'regimental badge area'
7) Sensation at the regimental badge area may be impaired or absent if there is axillary nerve damage

88

What does the Posterior Terminal Branch do?

1) Provides motor innervation to the Teres Minor muscle, and
2) Innervates the skin over the inferior part of the deltoid

89

What does the Anterior Terminal Branch do?

Provides motor innervation to the deltoid muscle

90

What could cause Axillary Nerve Injury?

Damaged by trauma to the shoulder of fracture of the surgical neck of the humerus

91

What are the motor functions muscles that the axillary nerve injury could cause?

Paralysis of the deltoid and Teres minor muscles

92

What happens when there is paralysis of the deltoid and Teres minor muscles

Patient is unable to abduct the affected limb

93

What happens to the sensory function when there is an axillary nerve injury?

The upper lateral cutaneous nerve of arm will be affected resulting in loss of sensation over the regimental badge area.