Peripheral Nerve Injuries Flashcards
What does the Median nerve innervate?
MEAT LOAF
M = median nerve
T = pronator teres
L = lumbricals (1,2)
A = abductor pollicis brevis
F = flexors (wrist + fingers) except FCU/FDP
T/F: the Median nerve supplies muscles in the ARM
F: only innervates forearm and wrist/hand musculature
The anterior interosseous nerve is (motor/sensory/combined)
Motor ONLY
The median nerve passes through the 2 heads of which muscle?
Pronator Teres
The anterior interosseous and palmar cutaneous nerves come from which nerve?
Median
What is the important thing to know about the palmar cutaneous’s relationship with the carpal tunnel?
The palmar cutaneous nerve runs OVER the carpal tunnel, not through it.
What median nerve entrapment leads to motor and sensory loss in the entire distribution AND affects the Pronator Teres?
Compression under the Ligament of Struthers
- This location is proximal to the Pronator Teres, so the innervation is affected.
What is a positive Pronator Teres Syndrome test?
Reports of pain or paresthesia with resisted pronation and extension of the elbow.
Is the Pronator Teres affected in Pronator Teres Syndrome?
No, it’s innervation is intact.
What are the special tests used to detect Pronator Teres Syndrome?
(+) Pronator Teres Syndrome test
(+) Tinel’s sign in the forearm
(-) Phalen’s test
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?
This is describing Pronator Teres Syndrome, which affects the Median nerve at the Pronator Teres muscle.
T/F: Anterior Interosseous Syndrome presents with motor and sensory impairments.
F: AIN is a motor-only nerve
Your patient is unable to make an OK sign (Kiloh-Nevin sign). What nerve do you suspect is affected?
Anterior Interosseous Nerve
Night pain is a hallmark symptom of which nerve entrapment?
Carpal Tunnel Syndrome
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?
Flick maneuver: shaking hands decreases pain
Common in Carpal Tunnel Syndrome
What are the special tests for Carpal Tunnel Syndrome?
(+) Tinel’s at the wrist
(+) Phalen’s test
(+) Reverse Phalen’s test
Carpal tunnel syndrome presents with (hypothenar/thenar) muscle atrophy?
Thenar eminence since the Median nerve supplies motor innervation there.
What is inside of the Carpal Tunnel?
Median nerve
Flexor tendons:
flexor digitorum superficialis
flexor digitorum profundus
flexor pollicis longus
Is sensation of the thenar eminence intact or diminished with carpal tunnel syndrome?
Intact: sensation for thenar eminence is innervated by palmar cutaneous nerve, which is not affected in carpal tunnel syndrome
Carpal Tunnel or Pronator Teres Syndrome:
Which one has diminished sensation to thenar eminence?
Pronator teres syndrome
Carpal Tunnel or Pronator Teres Syndrome:
Which one presents with pain in the forearm?
Pronator teres syndrome
What does the Radial nerve innervate?
BEAST
B: brachioradialis
E: extensors
A: anconeus/abductor pollicis longus
S: supinators
T: triceps
The radial nerve mostly innervates muscles on the (medial, posterior, lateral, anterior) side of the arm/forearm.
Posterior
T/F: Radial nerve supplies sensation to the hand, forearm, and arm.
True
At the supinator, the radial nerve branches off into what nerve?
Posterior interosseous nerve
Posterior interosseous nerve innervates all wrist/finger extensors except these 2:
Extensor carpi radialis longus
Supinator
These are innervated by the radial nerve.
What is a key way to differentiate radial tunnel syndrome from lateral epicondylitis?
Location of pain for radial tunnel syndrome will be 5cm distal to lateral epicondyle.
Wartenberg’s syndrome is a purely (sensory/motor) condition which affects what nerve?
Sensory
Radial
What muscles does the Ulnar nerve innervate?
MAFIA
M: medial lumbricals (4-5)
A: adductor pollicis
F: FCU/FDP ulnar side (3/4)
I: interossi
A: abductor digiti minimi
What is the sensory distribution of the Ulnar nerve?
1/2 fourth digit
all of fifth digit
What are the two sites of Ulnar nerve entrapment we need to know?
Cubital Tunnel
Guyon’s Canal
What is the sensory distribution of the median nerve?
Palmar sides of digits 1-3 and half of 4.
Distal ends of dorsal sides of fingers 1-3 and half of 4.
What is the sensory distribution of the radial nerve?
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.
T/F: The Ulnar nerve innervates some muscles in the thenar eminence.
T: Ulnar nerve innervated adductor pollicis and flexor pollicis brevis which are in the thenar eminence
The hypothenar eminence is innervated by which nerve?
Ulnar
Where is Guyon’s Canal?
Between the hook of the hamate and the transverse carpal ligament. Also near pisiform.
For both cubital tunnel syndrome and guyon’s canal syndrome, what tests will be positive?
(+) Froment paper sign
(+) Wartenberg sign
(+) Tinel’s sign at site of compression
In Guyon’s canal syndrome, what wrist/hand muscle is spared?
Flexor digitorum profundus is spared because it originates in the forearm
