Peripheral Nerve

Question 1

What roots contribute to the suprascapular nerve?

Answer 1

C5, C6 (occasionally C4)

Question 2

What part of the brachial plexus does the suprascaular nerve arise?

Answer 2

The upper trunk

Question 3

What muscles does the suprascapular nerve contribute to?

Answer 3

supraspinatus and infraspinatus muscles (and there is a sensory component)

Question 4

What are symptoms of suprascapular nerve injury?

Answer 4

Dull, aching pain in the superior and/or posterolateral shoulder that can radiate down the arm or into the neck. If the injury is distal to the spinoglenoid notch, patients may not complain of pain at all. Additional symptoms include a sense of instability if there is associated shoulder pathology, such as a labral or rotator cuff tear.

Question 5

Physical exam findings for suprascapular nerve injury?

Answer 5

Most common findings: atrophy of the infraspinatus and/or supraspinatus- nearly 80% of cases

Tenderness to palpation posterior to the AC joint and/or the posterosuperior joint line.

Pain may be exacerbated by cross-body adduction and internal rotation.[47]

Weakness with shoulder external rotation and/or shoulder abduction.

However, if the nerve injury is at or distal to the spinoglenoid notch and as a result, only the infraspinatus is affected, weakness may not be as pronounced given the patient’s deltoid, supraspinatus, and teres minor can aid in functional and strength compensation.

A specific physical exam maneuver: SSN stretch test. This test consists of laterally rotating the patient’s head away from the painful shoulder and retracting the neck and shoulder. A positive test is when the pain at the posterior shoulder is exacerbated

Question 6

During surgery, how do you test nerve fascicles to determine if they contribute to motor function of the nerve?

Answer 6

Portable nerve stimulator

Stimulation parameters: 1-2mA

Question 7

What are signs of early peripheral neuropathy on EMG?

Answer 7

Increased latency- which is due to demyelination

Question 8

What are signs of late radiculopathy on EMG?

Answer 8

Decreased amplitude secondary to neuronal loss

Question 9

What is the cause of pain or numbness in the hand after a carpal tunnel release?

Answer 9

Injury to the palmar percutaneous branch

Question 10

If there is thenar motor branch injury during a CTR, what is the treatment?

Answer 10

Allograft repair?

Question 11

If the palmar aspect of the hand (as opposed to just the first three fingers) is involved in the patient’s Median neuropathy symptoms what does that imply?

Answer 11

The lesion is proximal to the carpal tunnel

Question 12

If you see the benediction sign with attempt to form a fist what does that imply?

Answer 12

There is involvement of the long flexors so this is a more proximal lesion of the median nerve like at the level of the pronator teres or the flexor digitorum superficialis arch

Question 13

What causes the inability to make an ok sign with the hand?

Answer 13

AIN palsy- flexor policus longs and the lateral aspect of the flexor digitorum profundus

Question 14

If there is sensory sparing of the dorsal aspect of hand in an ulnar distribution what does that imply

Answer 14

Guyon canal at the wrist is where the nerve is compressed bc this distally, the canal does not contain the dorsal cutaneous branch

Question 15

What are the bony landmarks for an ulnar nerve decompression? Where is the incision placed?

Answer 15

Small “v” shaped incision between the olecranon and the medial epicondyle

Question 16

What is the classic exam finding for ulnar neuropathy?

Answer 16

Wartenberg sign- where the 5th digit cannot adduct to joint the other fingers

Question 17

What is the band called that covers the ulnar nerve? What is it composed of?

Answer 17

Osborne’s band in the distal decompression this is located between the two heads of flexor carpi ulnaris

Question 18

What fascial bands must be released to decompress the ulnar nerve?

Answer 18

The superficial and deep fascia of the flexor carpi ulnaris

Question 19

When should you be transposing the ulnar nerve?

Answer 19

With recurrence of ulnar neuropathy

There is a higher incidence of injury so it should not be performed up front for virgin neuropathy

Question 20

For an ulnar nerve transposition, how far does your incision need to be?

Answer 20

20cm! 10cm above and 10cm below the medial epicondyle

Question 21

With an ulnar nerve transposition, what nerve needs to be safe guarded during the dissection and transposition?

Answer 21

Median antebrachial cutaneous nerve which travels w a vein

Question 22

What structure poses risk to the ulnar nerve following a transposition if it is not resected?

Answer 22

Median intermuscular septum

Question 23

The ulnar nerve is located where?

What is the distal component of decompression required? What muscle contributes?

Answer 23

Within the medial elbow between the medial epicondyle and the olecranon within the cubital tunnel
Within the distal aspect of the cubital tunnel exists Osborne’s band which is connective tissue that originated at the heads of the flexor carpi ulnaris

Question 24

What is the pathway of the ulnar nerve proximal to the elbow?

Answer 24

The ulnar nerve is the most medial terminal branch off of the brachial plexus (medial aspect of the M with musculocutaneous and median)-
It descends posterior to the pec major and medial to the brachial artery. At the inferior border of the pec it moves more medically and pierces the intermuscular septum 8cm above the medial epicondyle.
From here it descends medially on the anterior surface of the medial head of the triceps where it is invested by some fibers of the triceps called the arcade of Struthers
It then passes into the ulnar groove at the entrance of the cubital tunnel
In passage through the cubital tunnel it goes from the extensor surface of the arm to the flexor surface of the forearm.
As it exits the cubital tunnel it does so through the two heads of the flexor carpi ulnaris

Question 25

Where does the medial antebrachial cutaneous nerve arise?

What does it supply

Answer 25

Medial cord of the brachial plexus (proximal to the branch point of the medial and ulnar nerves)
Sensation of the medial forearm down to the level of the wrist