Week 6: Practical applications

Question 1

What is Erb’s palsy?

Answer 1

• paralysis of the arm caused by injury to the upper brachial plexus, specifically C5–C6 nerves
• can happen to babies during delivery and adults due to trauma

Question 2

What is Klumpke’s palsy?

Answer 2

• paralysis of the lower parts of the brachial plexus
• specifically C8-T1
• can happen to babies during delivery and adults during trauma

Question 3

What is an obstetric upper brachial plexus injury?

Answer 3

• occurs due to excessive stretching of the baby’s neck during delivery, causing damage to C5 and C6 nerve roots
• this stretching usually happens when the baby’s are ‘stuck’
• C5,6 and possibly C7

Question 4

Why would a patient with Erb’s palsy be unable to abduct their arm?

Answer 4

• because the injury is to C5/6 so teres minor and deltoid would not work as they are innervated by the axillary nerve
• arm is limp

Question 5

In a patient with Erb’s palsy, why can’t the elbow me flexed?

Answer 5

• musculocutaneous is also impacted
• this innervates biceps and brachialis
• these are both flexors of the elbow so the elbow cannot be flexed

Question 6

What is a typical cause of adult upper brachial plexus injuries?

Answer 6

motorbike accidents

Question 7

How would an obstetric lower brachial plexus injury occur?

Answer 7

due to excessive pulling on the baby’s upper limb during delivery causing damage to C8 and T1 nerve roots (less common than Erb’s palsy)

Question 8

When does an adult lower brachial plexus injury occur?

Answer 8

when excessive force is placed on an abducted shoulder e.g grasping to prevent a fall

Question 9

The function of which nerve will be impaired by a C8 and T1 root injury?

Answer 9

Ulnar

Question 10

What does the ulnar nerve innervate?

Answer 10

Arm: nothing
Forearm: FCU, medial 1/2 of FDP
Hand: Hypothenar eminence, adductor pollicis, all the interossei, medial 2 lumbricals

Question 11

Which areas of the skin are innervated by the ulnar nerve?

Answer 11

medial side of hand and forearm

Question 12

Based on the previous questions, What would be the result of a lower bP injury?

Answer 12

• paralysis of the majority of the intrinsic hand muscles

- ‘claw hand’

Question 13

A LBP injury may be associated with Horner’s syndrome. What are the features of Horner’s syndrome?

Answer 13

• ptosis - drooping of upper eyelid
• miosis - excessive constriction of the pupil
• anhidrosis - absence of sweating
• vasodilation

Question 14

What would be the effect of a low lesion of the radial nerve?

Answer 14

• motor function would not be impaired (as the radial nerve doesn’t innervate any muscles in hand)
• would only lead to a sensory deficit over the dorsolateral aspect of the hand

Question 15

Which muscles does the median nerve innervate?

Answer 15

• Almost all anterior forearm flexor muscles - PT, palmaris longus, FCR, FDS, lateral half of FDP, FPL, PQ
• Thenar eminence (not adductor pollicis) (APB, FPB, OP), lateral 2 lumbricals (digits 2&3)
• Skin over lateral 1/2 of the palm of the hand

Question 16

Which muscles does the radial nerve innervate?

Answer 16

• All posterior compartment muscles
• Triceps
• All forearm extensors - thumb, wrist, fingers, APL
• No muscles in hand
• Skin over parts of the posterior arm, forearm, ASB and dorsolateral hand

Question 17

Which muscles does the ulnar nerve innervate?

Answer 17

• Almost all intrinsic hand muscles - adductor pollicis, hypothenar eminence (ADM, FDM, ODM), medial 2 lumbricals (to 4th and 5th digits), all interossei
• 1 1/2 anterior forearm flexors (FCU & half of FDP)
• Skin over medial 1/2 of the hand (palm and dormsum)

Question 18

Which condition develops from a high radial nerve lesion?

Answer 18

• ‘wrist drop’
• paralysis of forearm extensors
• unable to extend wrist, fingers and thumb
• sensory loss over dorsolateral hand
• can still weakly extend the elbow, as by this point the radial nerve has usually sent a branch to the long head of the triceps

Question 19

Which condition develops from a high median nerve lesion?

Answer 19

• ‘Bishop’s hand’
• unable to flex 2nd and 3rd digits as FDP (and FDS) is paralysed
• also unable to fully straighten the 2nd and 3rd as the lumbricals are paralysed, but are essential in extension
• can fully flex and extend 4th and 5th digits as FDP and lumbricals are innervated by ulnar nerve in these fingers

Question 20

What is a ‘simian hand’?

Answer 20

• lower medial nerve lesion
• thenar wasting
• fine movements of digits 2&3 impaired

Question 21

What is a ‘claw hand’ and what is its key feature?

Answer 21

• high or low lesion of the ulnar nerve

- hyperextension at the MCPJs

Question 22

What is meant by ‘ulnar paradox’?

Answer 22

• lower lesions of the ulnar nerve cause a more severe deformity than high ones, even though fewer muscles are paralysed
• this is because with a high lesion, there is less flexion at the IPJs so the ‘claw’ doesn’t look as bad

Question 23

Cardiac cauterisation can be done through which nerves?

Answer 23

radial or ulnar

Question 24

What is the relationship between frequency of an US wave and resolution of image?

Answer 24

higher frequency = better resolution (however, the lower the frequency, the better the depth of penetration)

Question 25

What is a doppler?

Answer 25

• measures difference in frequency of the emitted and collected doppler wave
• provides colour