Peripheral Nerve Injuries

Question 1

What does the Median nerve innervate?

Answer 1

MEAT LOAF
M = median nerve
T = pronator teres
L = lumbricals (1,2)
A = abductor pollicis brevis
F = flexors (wrist + fingers) except FCU/FDP

Question 1

T/F: the Median nerve supplies muscles in the ARM

Answer 1

F: only innervates forearm and wrist/hand musculature

Question 2

The anterior interosseous nerve is (motor/sensory/combined)

Answer 2

Motor ONLY

Question 3

The median nerve passes through the 2 heads of which muscle?

Answer 3

Pronator Teres

Question 4

The anterior interosseous and palmar cutaneous nerves come from which nerve?

Answer 4

Median

Question 5

What is the important thing to know about the palmar cutaneous’s relationship with the carpal tunnel?

Answer 5

The palmar cutaneous nerve runs OVER the carpal tunnel, not through it.

Question 6

What median nerve entrapment leads to motor and sensory loss in the entire distribution AND affects the Pronator Teres?

Answer 6

Compression under the Ligament of Struthers
- This location is proximal to the Pronator Teres, so the innervation is affected.

Question 7

What is a positive Pronator Teres Syndrome test?

Answer 7

Reports of pain or paresthesia with resisted pronation and extension of the elbow.

Question 8

Is the Pronator Teres affected in Pronator Teres Syndrome?

Answer 8

No, it’s innervation is intact.

Question 9

What are the special tests used to detect Pronator Teres Syndrome?

Answer 9

(+) Pronator Teres Syndrome test
(+) Tinel’s sign in the forearm
(-) Phalen’s test

Question 10

Patient presents with paresthesia on digits 1-3.5 and thenar eminence on palmar side.
Patient has decreased grip strength in affected arm, but is able to pronate their forearm.
What nerve is entrapped and where?

Answer 10

This is describing Pronator Teres Syndrome, which affects the Median nerve at the Pronator Teres muscle.

Question 11

T/F: Anterior Interosseous Syndrome presents with motor and sensory impairments.

Answer 11

F: AIN is a motor-only nerve

Question 12

Your patient is unable to make an OK sign (Kiloh-Nevin sign). What nerve do you suspect is affected?

Answer 12

Anterior Interosseous Nerve

Question 13

Night pain is a hallmark symptom of which nerve entrapment?

Answer 13

Carpal Tunnel Syndrome

Question 14

Your patient shakes their hands quickly to relieve their paresthesia symptoms in their hand.
What is the name for shaking your hands to relieve pain and what condition does this point to?

Answer 14

Flick maneuver: shaking hands decreases pain
Common in Carpal Tunnel Syndrome

Question 15

What are the special tests for Carpal Tunnel Syndrome?

Answer 15

(+) Tinel’s at the wrist
(+) Phalen’s test
(+) Reverse Phalen’s test

Question 16

Carpal tunnel syndrome presents with (hypothenar/thenar) muscle atrophy?

Answer 16

Thenar eminence since the Median nerve supplies motor innervation there.

Question 17

What is inside of the Carpal Tunnel?

Answer 17

Median nerve
Flexor tendons:
flexor digitorum superficialis
flexor digitorum profundus
flexor pollicis longus

Question 18

Is sensation of the thenar eminence intact or diminished with carpal tunnel syndrome?

Answer 18

Intact: sensation for thenar eminence is innervated by palmar cutaneous nerve, which is not affected in carpal tunnel syndrome

Question 19

Carpal Tunnel or Pronator Teres Syndrome:
Which one has diminished sensation to thenar eminence?

Answer 19

Pronator teres syndrome

Question 20

Carpal Tunnel or Pronator Teres Syndrome:
Which one presents with pain in the forearm?

Answer 20

Pronator teres syndrome

Question 21

What does the Radial nerve innervate?

Answer 21

BEAST
B: brachioradialis
E: extensors
A: anconeus/abductor pollicis longus
S: supinators
T: triceps

Question 22

The radial nerve mostly innervates muscles on the (medial, posterior, lateral, anterior) side of the arm/forearm.

Answer 22

Posterior

Question 23

T/F: Radial nerve supplies sensation to the hand, forearm, and arm.

Answer 23

True

Question 24

At the supinator, the radial nerve branches off into what nerve?

Answer 24

Posterior interosseous nerve

Question 25

Posterior interosseous nerve innervates all wrist/finger extensors except these 2:

Answer 25

Extensor carpi radialis longus
Supinator
These are innervated by the radial nerve.

Question 26

What is a key way to differentiate radial tunnel syndrome from lateral epicondylitis?

Answer 26

Location of pain for radial tunnel syndrome will be 5cm distal to lateral epicondyle.

Question 27

Wartenberg’s syndrome is a purely (sensory/motor) condition which affects what nerve?

Answer 27

Sensory
Radial

Question 28

What muscles does the Ulnar nerve innervate?

Answer 28

MAFIA
M: medial lumbricals (4-5)
A: adductor pollicis
F: FCU/FDP ulnar side (3/4)
I: interossi
A: abductor digiti minimi

Question 29

What is the sensory distribution of the Ulnar nerve?

Answer 29

1/2 fourth digit
all of fifth digit

Question 30

What are the two sites of Ulnar nerve entrapment we need to know?

Answer 30

Cubital Tunnel
Guyon’s Canal

Question 31

What is the sensory distribution of the median nerve?

Answer 31

Palmar sides of digits 1-3 and half of 4.
Distal ends of dorsal sides of fingers 1-3 and half of 4.

Question 32

What is the sensory distribution of the radial nerve?

Answer 32

Dorsum of the hand except for ulnar side (past half of 4th digit) and distal fingers.
On the palmar end, right at the base of the thumb.

Question 33

T/F: The Ulnar nerve innervates some muscles in the thenar eminence.

Answer 33

T: Ulnar nerve innervated adductor pollicis and flexor pollicis brevis which are in the thenar eminence

Question 34

The hypothenar eminence is innervated by which nerve?

Answer 34

Ulnar

Question 35

Where is Guyon’s Canal?

Answer 35

Between the hook of the hamate and the transverse carpal ligament. Also near pisiform.

Question 36

For both cubital tunnel syndrome and guyon’s canal syndrome, what tests will be positive?

Answer 36

(+) Froment paper sign
(+) Wartenberg sign
(+) Tinel’s sign at site of compression

Question 37

In Guyon’s canal syndrome, what wrist/hand muscle is spared?

Answer 37

Flexor digitorum profundus is spared because it originates in the forearm