Anatomy Limbs 5 - Brachial Plexus Flashcards

1
Q

How does the brachial plexus divide as it moves distally?

A

Roots - Trunks - Divisions - Cords - Terminal branches

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2
Q

What muscle does the long thoracic nerve supply?

A

Serratus anterior

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3
Q

What muscle does the thorax-dorsal nerve supply?

A

Latissimus dorsi

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4
Q

Which spinal cord nerves make up the brachial plexus?

A

C5 - T1

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5
Q

Which nerve roots form the upper trunk?

A

C5 and C6

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6
Q

Which nerve roots form the middle trunk?

A

C7

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7
Q

Which nerve roots form the lower trunk?

A

C8 and T1

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8
Q

There is a lateral cord, posterior cord and medial cord. They are all named in relation to?

A

The axillary artery

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9
Q

Which nerve roots supply the shoulder girdle muscles?

A

c3-c7

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10
Q

Which nerve roots supply the shoulder joint muscles and elbow flexors?

A

C5-C6

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11
Q

Which nerve roots supply the elbow joint extensors?

A

C7-C8

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12
Q

Which nerve roots supply the wrist and coarse hand muscles

A

C6-C8

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13
Q

Which nerve roots supply small muscles of the hand (fine movements)

A

C8-T1

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14
Q

What are the terminal divisions of the posterior cord?

A

Axillary nerve and radial nerve

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15
Q

How is the axillary nerve commonly damaged?

A

Shoulder dislocation and fracturing the surgical neck of the humerus

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16
Q

Which 2 muscles does the axillary nerve innervate?

A

Deltoid and teres minor

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17
Q

How is axillary nerve damage assessed?

A

Test the superior lateral part of the shoulder/arm. Supplied by superior lateral cutaneous nerve of arm.

Area of anaesthesia if axillary nerve damaged

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18
Q

When and why is the radial nerve commonly damaged?

A

Radial nerve runs closely with the shaft of the humerus - so is susceptible in humeral fractures

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19
Q

What muscle of the arm does the radial nerve supply?

A

Triceps, and also muscles of the hand

20
Q

How can radial nerve damage be assessed?

A

“Wrist drop” and anaesthesia of the dorsal hand

Radial nerve more proximally may also result in muscle masss wastage

ALSO LOSS OF POWER GRIP

21
Q

Which cord is the musculocutaneous nerve derived from?

A

The lateral cord

22
Q

Which muscles does the musculocutaneous nerve supply?

A

Anterior muscles of the arm

23
Q

Why is the musculocutaneous nerve not often injured in trauma?

A

It is well protected by muscles

24
Q

When might the musculocutaneous nerve be injured?

A

During surgery for breast cancer

25
From which cord is the ulnar nerve derived?
Medial cord
26
Which epicondyle does the ulnar nerve run behind?
Medial epicondyle
27
Which muscles does the ulnar nerve supply?
Flexor carpi ulnari and ulnar half of flexor digitorum profundus
28
Which muscles of the hand does the ulnar nerve supply?
Hypothenar muscles, lumbricals (4 and 5) and ALL dorsal/palmar interossei
29
When is the ulnar nerve commonly injured?
1. Injury to medial epicondyle of humerus | 2. Self harm - slashing wrists
30
How can you distinguish ulnar nerve injury in someone?
Claw-like appearance Due to loss of lumbrical contraction - causes loss of flexion in metacarpal-phalangeal joints and weakened extension in the first interphalangeal joints
31
Which digits are largely spared in ulnar nerve damage?
Thumb, index finger and middle fnger
32
Why might ulnar injury at the wrist appear worse than ulnar injury at the elbow (counterintuitively)
at elbow, ulnar half of FDP also injured - meaning weaker flexion of interphalangeal joints = less claw like appearance than just at the wrist
33
Which cords form the median nerve?
Lateral and medial cords
34
What structure does the median nerve pass under en route to the hand
Flexor retinaculum
35
Which digits does the median nerve supply?
The thumb, index and middle fingers
36
What other region does the median nerve supply?
Proximal palmar regions
37
Wasting of the thenar eminence is a symptom of?
Carpal tunnel syndrome
38
Where is sensory anaesthesia present in carpal tunnel syndrome?
Thumb, much of the radial Half of the palm (but not the hypothenar region), index finger and much of middle finger
39
How come the long thoracic nerve is easily damaged?
It runs quite superficially to the serrates anterior muscle, so susceptible to trauma/stabbing etc
40
How can you tell damage to the long thoracic nerve?
Pressing against a wall = leads to winging of the scapula due to loss of activity from serratus anteior
41
Upper root injury (aka Erb-Duchenne palsy) can be caused by?
Falls which puts strain on the neck/ giving birth - can damage C5 and C6
42
Damage to the upper root can cause?
"Waiters tip" Shoulder and anterior arm affected - forearm pronated due to lack of biceps supination
43
How can damage to the lower roots occur (C8/T1)
Overabduction due to gripping overhead to break a fall or in difficult births
44
Which cords can be affected by damage to the lower roots (C8/T1)
Medial cord and posterior cord
45
What is the outcome of lower root injury?
"Klumpke's Palsy" - Klumpkes monkey falls from a tree T1 - mainly supplies small muscles of hand via median and ulnar nerves - loss in activity gives clawed appearance Clawed due to hyperextension of MCP joints and strong flexion of the fingers