MSK- upper limb, functional anatomy and clinical applications

Question 1

musculocutaneous nerve injury

Answer 1

Rare isolated lesion
Lesions to the upper arm and shoulder (e.g., humeral fracture)

Symptoms:
Weakness of elbow flexion – paralysis of muscles (motor)
Sensory impairment on the extensor aspect of the forearm (sensory) – paresthesia

Usually do not occur in isolation
Looked at it last week – nerve can be damaged by shoulder dislocation, but ALSO humeral fracture (e.g., humeral neck fracture)
Symptoms – both motor and sensory
Paresthesia - tingling, numbness or “pins and needles.

Question 2

axiallary nerve injury

Answer 2

Traumatic injury (most common)
Dislocation of the shoulder, humeral fracture (surgical neck)

Symptoms:
Deltoid weakness – paralysis (motor) clinically evident!
Sensory loss – patch on outer aspect of arm (sensory)

If caused by fracture of the humerus – fracture at the surgical neck
MOTOR – innervates deltoid and teres minor BUT weakness of deltoid most clinically evident! (think about movements of the deltoid – loss of function of this muscle)
Sensory – patch on outer aspect of the arm

Question 3

median nerve injury

Answer 3

Carpal tunnel syndrome – Sensory

Most common compression neuropathy
repetitive activities, inflammation of tendons, fractures…
commonly associated with diabetes, rheumatoid arthritis, pregnancy, menopause

Nerve compressed beneath transverse carpal ligament
Weakness when gripping
Pain and numbness / ‘Pins and needles’ feeling in the hand

Activity worsen the symptoms

Nerve conduction test, Durkan test, Phalen’s test, Tinel’s test

More common in women than men (3:1 ratio)
Risks factors – diabetes, pregnancy etc…
Phalen’s test – to check for syndrome: to flex patient’s wrists and hold together for 1 minute – positive test: tingling feeling in the thumb, index and middle fingers and half of the ring finger
Confirmation of diagnosis – medical imaging (e.g., ultrasound)

Question 4

median nerve injury

Answer 4

Uncommon entrapment neuropathy – elbow region, 4 different sites
Pain to distal arm and proximal forearm
Weakness in muscles (motor)
Sensory impairment to palm (sensory)

Pronator syndrome:
Uncommon. Different types of entrapment of the nerve – in this case entrapment happens quite high in the forearm, just after cubital fossa
Symptoms might be aggravated by movement

Question 5

radial nerve injury

Answer 5

Traumatic lesion/damage at the radial groove (humerus)
Global paralysis of muscles of posterior compartment! (motor)
Reduced sensation posterior aspect of upper limb and lateral aspect of the dorsum of the hand (sensory)

wrist drop, clinical sign
Usually occurs where the radial nerve passes on the radial groove of the humerus.

Question 6

ulnar nerve injury

Answer 6

Ulnar tunnel syndrome – Claw hand

Lesion at the wrist/compression in the Guyon’s canal (between the pisiform and hook of the hamate, and the transverse carpal ligament)
3 zones of compression

Zone 2 – deep branch of ulnar (motor)
Weakness of the interossei, lumbricals and hypothenar muscles
Able to make a full fist BUT not able to fully extend 4th and 5th fingers (IP)

IF sensory is affected as well – tingling and numbness feeling

Question 7

ulnar tunnel syndrome pt2

Answer 7

Ulnar tunnel syndrome – lesion or compression of the nerve at the ulnar (Guyon’s) canal (canal between the carpal bones, specifically pisiform and hook of hamate) by a ganglion (full filled cyst) or repeated trauma.
There are 3 different zones in which the nerve can be compressed
ZONE 1 – nerve damage only sensory ( metacarpals)
ZONE 2 – nerve damage only motor ( carpals)
ZONE 3 – nerve damage both (wrist)

INTEROSSEI (PALMAR AND DORSAL) RESPONSIBLE FOR EXTENSION OF THE FINGERS AT THE INTERPHALANGEAL JOINTS) + LUMBRICALS 4 AND 5 ALSO RESPONSIBLE FOR IP EXTENSION

Surgical exposure of the nerve may be necessary when there is no history of trauma.