Anatomy Limbs 5 - Brachial Plexus

Question 1

How does the brachial plexus divide as it moves distally?

Answer 1

Roots - Trunks - Divisions - Cords - Terminal branches

Question 2

What muscle does the long thoracic nerve supply?

Answer 2

Serratus anterior

Question 3

What muscle does the thorax-dorsal nerve supply?

Answer 3

Latissimus dorsi

Question 4

Which spinal cord nerves make up the brachial plexus?

Answer 4

C5 - T1

Question 5

Which nerve roots form the upper trunk?

Answer 5

C5 and C6

Question 6

Which nerve roots form the middle trunk?

Answer 6

C7

Question 7

Which nerve roots form the lower trunk?

Answer 7

C8 and T1

Question 8

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

Answer 8

The axillary artery

Question 9

Which nerve roots supply the shoulder girdle muscles?

Answer 9

c3-c7

Question 10

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

Answer 10

C5-C6

Question 11

Which nerve roots supply the elbow joint extensors?

Answer 11

C7-C8

Question 12

Which nerve roots supply the wrist and coarse hand muscles

Answer 12

C6-C8

Question 13

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

Answer 13

C8-T1

Question 14

What are the terminal divisions of the posterior cord?

Answer 14

Axillary nerve and radial nerve

Question 15

How is the axillary nerve commonly damaged?

Answer 15

Shoulder dislocation and fracturing the surgical neck of the humerus

Question 16

Which 2 muscles does the axillary nerve innervate?

Answer 16

Deltoid and teres minor

Question 17

How is axillary nerve damage assessed?

Answer 17

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

Area of anaesthesia if axillary nerve damaged

Question 18

When and why is the radial nerve commonly damaged?

Answer 18

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

Question 19

What muscle of the arm does the radial nerve supply?

Answer 19

Triceps, and also muscles of the hand

Question 20

How can radial nerve damage be assessed?

Answer 20

“Wrist drop” and anaesthesia of the dorsal hand

Radial nerve more proximally may also result in muscle masss wastage

ALSO LOSS OF POWER GRIP

Question 21

Which cord is the musculocutaneous nerve derived from?

Answer 21

The lateral cord

Question 22

Which muscles does the musculocutaneous nerve supply?

Answer 22

Anterior muscles of the arm

Question 23

Why is the musculocutaneous nerve not often injured in trauma?

Answer 23

It is well protected by muscles

Question 24

When might the musculocutaneous nerve be injured?

Answer 24

During surgery for breast cancer

Question 25

From which cord is the ulnar nerve derived?

Answer 25

Medial cord

Question 26

Which epicondyle does the ulnar nerve run behind?

Answer 26

Medial epicondyle

Question 27

Which muscles does the ulnar nerve supply?

Answer 27

Flexor carpi ulnari and ulnar half of flexor digitorum profundus

Question 28

Which muscles of the hand does the ulnar nerve supply?

Answer 28

Hypothenar muscles, lumbricals (4 and 5) and ALL dorsal/palmar interossei

Question 29

When is the ulnar nerve commonly injured?

Answer 29

1. Injury to medial epicondyle of humerus

2. Self harm - slashing wrists

Question 30

How can you distinguish ulnar nerve injury in someone?

Answer 30

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

Question 31

Which digits are largely spared in ulnar nerve damage?

Answer 31

Thumb, index finger and middle fnger

Question 32

Why might ulnar injury at the wrist appear worse than ulnar injury at the elbow (counterintuitively)

Answer 32

at elbow, ulnar half of FDP also injured - meaning weaker flexion of interphalangeal joints = less claw like appearance than just at the wrist

Question 33

Which cords form the median nerve?

Answer 33

Lateral and medial cords

Question 34

What structure does the median nerve pass under en route to the hand

Answer 34

Flexor retinaculum

Question 35

Which digits does the median nerve supply?

Answer 35

The thumb, index and middle fingers

Question 36

What other region does the median nerve supply?

Answer 36

Proximal palmar regions

Question 37

Wasting of the thenar eminence is a symptom of?

Answer 37

Carpal tunnel syndrome

Question 38

Where is sensory anaesthesia present in carpal tunnel syndrome?

Answer 38

Thumb, much of the radial Half of the palm (but not the hypothenar region), index finger and much of middle finger

Question 39

How come the long thoracic nerve is easily damaged?

Answer 39

It runs quite superficially to the serrates anterior muscle, so susceptible to trauma/stabbing etc

Question 40

How can you tell damage to the long thoracic nerve?

Answer 40

Pressing against a wall = leads to winging of the scapula due to loss of activity from serratus anteior

Question 41

Upper root injury (aka Erb-Duchenne palsy) can be caused by?

Answer 41

Falls which puts strain on the neck/ giving birth - can damage C5 and C6

Question 42

Damage to the upper root can cause?

Answer 42

“Waiters tip”

Shoulder and anterior arm affected - forearm pronated due to lack of biceps supination

Question 43

How can damage to the lower roots occur (C8/T1)

Answer 43

Overabduction due to gripping overhead to break a fall or in difficult births

Question 44

Which cords can be affected by damage to the lower roots (C8/T1)

Answer 44

Medial cord and posterior cord

Question 45

What is the outcome of lower root injury?

Answer 45

“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