MSK Flashcards
Arms: Nerves Blood vessels Dislocations Hand nerves and tendons (133 cards)
Sensations lost in order in nerve compression
Light tough, pressure and vibration
Then pain and temperature
Causes of nerve compression in arm - 5 categories
Anatomical - fracture deformity, synovial fibrosis
Systemic - alcohol, diabetes, renal failure, Reynaud’s
Inflammatory - RA, infection, tenosynovitis
Mass - haematoma, lipoma
Fluid imbalance - pregnancy, obesity
Pathophysiology of nerve compression
Microvascular compression causes intraneural oedema which increases it
Increases pressure and vibratory threshold
Fibrosis, axonal loss, demyelination cause weakness or paralysis of motor nerve
Other signs and tests of nerve compression except motor and sensory - 4
2 point discrimation (>6mm = abnormal)
Skin - colour, temperature from SNS dysfunction
Electromyography
Nerve conduction studies
RF for carpal tunnel
MEDIAN TRAP: Myxoedema oEdema Diabetes Iatrogenic Acromegaly Neoplasm Trauma RA Amyloidosis Pregnancy
What is in carpal tunnel
Median nerve
Flexor pollicis longus tendon
4 FDS tendons
4 FDP tendons
Pathogenesis of carpal tunnel syndrome
Pressure increases
Epineural blood flow decreases and nerve becomes oedematous
Increasing pressure causes nerve conduction to decrease
Sx of carpal tunnel and tests
Paraesthesia and pain often at night on volar aspect of radial 3.5 digits
Tinel and Phalen
Loss of fine motor control and weakness = late
Nerve conduction test and EMG
Differentials for carpal tunnel syndrome
Cervical radiculopathy
Thoracic outlet syndrome
Peripheral neuropathies eg diabetess
Treatment of carpal tunnel
Activity modification, night splint, NSAIDS
Single corticosteroid injection
Operative release
Complications of surgery for carpal tunnel - 2
Ulnar neurovascular structures in Guyon canal can be injured if too ulnar
Damage to recurrent motor branch of median nerve if too radial
Where to find recurrent motor branch of median nerve
Kaplan line (from abducted thumb distal surface) and longitudinal line from web spaces of index and middle finger
Differentiate pronator syndrome and CTS
Pronator has forearm pain and palmar cutaneous median nerve sensory pain
What is the cubical tunnel
Floor = elbow joint capsule and MCL Sides = olecrattnon and median epicondylitis Roof = FCU fascia and fibrous band
Compression of ulnar nerve at medial epicondyle
Paralyse FCU, 1/2 FDP, interossei and medial 2 lumbricals
No abduction or adduction
4th and 5th digits reduced movement
1/2 4th and 5th digits no sensation
Compression of ulnar nerve at wrist
Paralyse medial 2 lumbricals and interossei
No finger abduction/adduction
Ulnar claw: cannot extend at IPs of 4th and 5th digits (unopposed flexor digitorum), but overextension at MCP (unopposed extensor digitorum)
Test for ulnar nerve
Froment’s test - paper between thumb and finger, pulling out causes thumb to flex as flexor pollicis is used to make up for lack of adductor pollicis
Nerve damage in axilla?
Radial = paralyse triceps and posterior forearm, so no wrist extension, no cutaneous innervation
Nerve damage in radial groove?
Radial nerve - paralyse posterior forearm - wrist drop, no dorsum cutaneous innervation
Posterior forearm paralysis but no wrist drop
Deep motor branch of radial nerve injury after elbow, paralysing post forearm except ECRL and supinator
Median nerve damage at elbow
Paralyse anterior forearm except FCU and 1/2 FDP
No pronation
Weak flexion
Hand of Benediction when make fist: cannot flex MCP or extend IPs (1-3)
Sensory loss of lateral 1/2 of hand
Median nerve damage at wrist
Paralyse thenar muscles and lateral 2 lumbricals
Hand of benediction and sensory loss of lateral 1/2 hand
Nerve damage on shoulder dislocation
Axillary nerve Paralyse deltoid and teres minor No abduction Can feel greater tuberosity Loss of regimental badge sensation
Nerve damage causing weakness of arm movements?
Musculocutaneous at axilla: - weak shoulder flexion from pec major - weak elbow flexion from brachioradialis - weak supination from supinator Lateral forearm sensory loss