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YR2: Limbs > Nerve injuries and consequences in the upper limb > Flashcards

Nerve injuries and consequences in the upper limb Flashcards

1
Q

What branches off the lateral, posterior and medial cords of the brachial plexus from proximal to distal?

A 
Lateral = 
Lateral pectoral
Musculocutaneous 
Median
Posterior = 
upper subscapular 
thoracodorsal
lower subscapular 
Axillary
Radial
Medial = 
medial pectoral
medial cutaneous nerve of the ARM
medial cutaneous nerve of the FOREARM
Ulnar
Median
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2
Q

The cords of the brachial plexus are named because of their position relative to what important structure?

A

Axillary artery

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3
Q 
Which spinal nerves make up each of the following nerves:
Dorsal scapular
Long Thoracic
Suprascapular 
Subclavian 
Lateral Pectoral
Medial Pectoral
Upper Subscapular 
Lower Subscapular 
Thoracodorsal
Axillary 
Musculocutaneous
Radial
Median
Ulnar
A 
Dorsal Scapular: C5
Long Thoracic: C5-7
Suprascapular: C5 + 6 (+C4)
Subclavian: C5 + 6 (+C4)
Lateral Pectoral: C5-7
Medial Pectoral: C8 + T1
Upper Subscapular: C5
Lower Subscapular: C6
Thoracodorsal: C6-8
Axillary: C5 + 6
Musculocutaneous: C5-7
Radial: C5-T1
Median: C6-8 + T1
Ulnar- C8 + T1
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4
Q

Which two muscles, which start outside the hand, does the ulnar nerve innervate?

A

Flexor carpi ulnaris (FCU)

Ulnar half of flexor digitorum profundus (FDP)

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5
Q

Which nerves supply the shoulder girdle muscles?

A

C3-C7

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6
Q

Which nerves supply the shoulder muscles and elbow joint flexors?

A

C5+C6

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7
Q

Which nerves supply the elbow joint extensors?

A

C7 + C8

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8
Q

Which nerves are responsible for coarse wrist and hand movements?

A

C6-C8

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9
Q

Which nerves supply small muscles of the hand (fine movements)?

A

C8 + T1

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10
Q

Describe the dermatome pattern of the skin on the posterior of the upper limb?

A

Strips going from C6 (thumb) - C8 (ring+little) from top to bottom

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11
Q

Describe the dermatome pattern of the skin on the anterior of the upper limb?

A

Same as posterior side but there are dermatomes of C5 + T1 running down the middle with their apex at the wrist

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12
Q

Why is the dermatome pattern different to the cutaneous nerve pattern?

A

Dermatome: area of skin innervated by a single spinal nerve
A cutaneous nerve pattern is the area of skin innervated by a peripheral nerve
Peripheral nerves contain various spinal nerve root fibres so the cutaneous nerve pattern is very different to to the dermatome pattern.

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13
Q

What is the benefit of having a brachial plexus instead of having spinal nerves directly innervating the upper limb muscles?

A

If a muscle group is innervated by 1 nerve root, damage to that nerve root will cause total loss of function of the muscle. If it is innervated by >1 nerve root there may still be some function.

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14
Q

What does the axillary nerve supply and what branch of the axillary nerve is responsible for sensory innervation of the skin of the regimental badge area?

A

Deltoid + teres minor

Superior lateral cutaneous branch

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15
Q

How is the axillary nerve commonly damaged?

A

Shoulder dislocation

Fracture of surgical head of humerus

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16
Q

What are the consequences of axillary nerve damage?

A

Loss of function of deltoid (muscle wastage)

Anaesthesia or parasthesia of the regimental badge area

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17
Q

Describe the passage of the radial nerve through the arm.

A

Exits axilla posterior to axillary artery
Passes posterior to humerus in radial groove, with the deep brachial artery
Perforates the lateral intermuscular septum
Enters the cubital fossa
Divides into superficial radial nerve (sensory) + posterior interosseous nerve (motor)

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18
Q

How is the radial nerve commonly damaged?

A

Humeral fractures: because the radial nerve is closely associated with the humerus in the radial groove

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19
Q

What are the consequences of radial nerve damage?

A

Wrist drop
Anaesthesia of the dorsal hand (on the thumb side)
Wasting of posterior compartment muscles of arm + forearm

20
Q

What is the most important outcome in radial nerve injury and how does it happen?

A

Loss of the power grip
To allow extension, flexors of the fingers are slightly longer than they need to be.
So extension of the wrist allows shortening of flexors to maximise their efficiency + allow the power grip
Radial nerve palsy: can’t extend wrist anymore so can’t perform the power grip

21
Q

Describe the passage of the musculocutaneous nerve down the arm.

A

Exits axilla by piercing coracobrachialis
Descends between biceps brachii + brachialis, supplying both
Continues as the lateral cutaneous nerve of the forearm

22
Q

When can the musculocutaneous nerve be damaged?

A

Not often damaged by trauma because it’s well protected by anterior compartment muscles
It can be cut during surgery for breast cancer (removal of axillary lymph nodes)

23
Q

Describe the passage of the ulnar nerve down the arm.

A

Descends in the medial arm
Passes posterior to the medial epicondyle
Descends down the ulnar aspect of the forearm to the hand

24
Q

What are two common sites of damage of the ulnar nerve?

A

Injury to the medial epicondyle of the humerus

Injury to the wrist

25
Q

What situation commonly encountered by clinicians could cause injury at the wrist?

A

Self-harm

Attempted suicide

26
Q

Which muscles do the ulnar nerve innervate?

A

Flexor carpi ulnaris (FCU)
Ulnar half of flexor digitorum profundus (FDP)
All intrinsic hand muscles except LOAF (lumbricals 1+2, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis)

27
Q

Describe and explain the appearance of the hand in ulnar nerve injury.

A

Damage to the ulnar nerve causes loss of function of lumbricals 3+4
Lumbricals are responsible for flexion of the MCPs + extension of the IPJs
Loss of lumbrical function will cause flexion of the IPJs + extension of the MCPs
The hand has a half claw-like appearance (ring finger + little finger are flexed)

28
Q

What is the ulnar paradox? What causes it?

A

Claw is worse when lesion is at the wrist than at the elbow
Because lesion at the elbow will mean the ulnar nerve to both FDP (causes flexion of fingers) + lumbricals (cause extension of fingers) will not be functioning = less flexion of fingers
With a wrist lesion, FDP is still functioning + able to cause flexion whereas the lumbricals are not functioning + can’t cause extension
So with wrist lesions you get an unopposed flexion of fingers due to FDP, meaning flexion of the fingers is worse
‘the closer to the paw, the worse the claw’

29
Q

Describe the path of the median nerve down the arm.

A

Lateral + medial cords merge to form the median nerve, lateral to the axillary artery
Descends through the arm adjacent to the brachial artery with the nerve gradually crossing anterior to the artery to lie medial to the artery in the cubital fossa

30
Q

Which muscles do the median nerve supply?

A

All the anterior compartment of forearm muscles except FCU + ulnar half of FDP
Thenar muscles + lumbricals 1+2

31
Q

What are the contents of the carpal tunnel?

A

Median nerve
Flexor pollicis longus (FPL)
4 tendons of flexor digitorum superficialis (FDS)
4 tendons of flexor digitorum profundus (FDP)

32
Q

Describe the sensory innervation of the palmar surface of the hand.

A

Ulnar Nerve = little finger + ½ of ring finger
Median Nerve = ½ of ring finger + middle finger + index finger + ½ of thumb
Radial Nerve = small part of lateral side of thumb

33
Q

What branch comes off the median nerve before it enters the carpal tunnel?

A

Palmar cutaneous branch
Branches off the median nerve before the carpal tunnel + so sensation to the thenar eminence is spared in carpal tunnel syndrome

34
Q

Describe the appearance of a hand in long-term carpal tunnel syndrome.

A

Thenar eminence will be wasted

There will be a small triangle of muscle that is still prominent: adductor pollicis (as supplied by ulnar nerve)

35
Q

What are the consequences of carpal tunnel syndrome?

A

Loss of sensation + fine movement in lateral digits (thumb, index + middle finger)

36
Q

What are the consequences of injury to the long-thoracic nerve?

A

Winging of the scapula

Due to loss of function of serratus anterior

37
Q

What is Erb-Duchenne Palsy and what can it be caused by?

A

Damage to the upper roots (C5, C6)

Can be caused by over-abduction of the neck (e.g. falling on neck or delivering a baby)

38
Q

Describe the appearance of a patient with Erb-Duchenne Palsy.

A

Forearm pronated + wrist flexed

= ‘waiter’s tip’

39
Q

Why is the arm pronated in Erb-Duchenne Palsy?

A

C5 + C6 are part of the musculocutaneous nerve, which innervates biceps brachii
Lack of biceps supination causes the forearm to pronate
Many muscles are affected: shoulder + anterior arm

40
Q

What is the name given to lower nerve root injury and what is it caused by?

A

Klumpke’s Palsy

Caused by over-abduction of the arm due to gripping overhead to break a fall or pulling a limb in childbirth

41
Q

Which nerves are usually affected in lower nerve root injury?

A

T1 (+ sometimes C8)

42
Q

Which muscles does T1 innervate?

A

T1 mainly supplies the small muscles of the hand via the median + ulnar nerves so there is a loss of activity in many of the hand muscles

43
Q

What are the consequences of Klumpke’s Palsy?

A

Whole hand is clawed

Due to loss of activity of the lumbricals: reduced extension of the IPJs + reduced flexion of the MCP joints

44
Q

What mnemonic is used to remember the subsections of the brachial plexus?

A

Read that damn cadaver book
Roots (formed from anterior rami: C5-T1)
Trunks (Upper: C5,6, Middle: C7, Lower: C8,T1)
Divisions (Anterior/ Posterior)
Cords (upper 2 anterior form lateral, lower anterior forms medial, all 3 posterior form posterior)
Branches (peripheral nerves)

45
Q

What mnemonic is used to remember the contents of the cubital fossa?

A 
Really need beer to be at my nicest
Radial nerve
Brachial tendon
Brachial artery 
Median nerve

YR2: Limbs (8 decks)

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