Nerve Injuries Flashcards
What is the motor/sensory distribution of the radial nerve?
Stems from C5-T1 (posterior branches of brachial plexus)
Motor: supplies extensors of the arm both in elbow and wrist
sensory : supplies most of posterior arm and radial side of posterior hand
Damage of the radial nerve can cause
crutch palsy/saturday night palsy = inability to extend elbow/hand leads to wrist drop
What is the muscular and sensory distribution of the median nerve?
motor = most of forearm and LOAF in hand (first and second lumbricals, opponens policis, abductor pollicis, and flexor pollicis brevis)
Sensory= first three fingers and radial half of palm in hand
What are some causes of injury to the median nerve?
laceration at the elbow
fractures at the elbow
laceration of the wrist
carpal tunnel
What may result from injury to the median nerve?
wasting of the thenar eminence
ape like hand due to loss of the long flexor tendons
loss/weakness of pronation
sensory loss to the radial half of hand
Injury to what muscles causes the pointing sign deformity?
pointing sign is due to inability to FLEX finger = loss of flexor digitorum superficialis and profundus = loss of median nerve
*test with clasping test*
What are the symptoms of carpel tunnel syndrome?
pins and needles in first two and half fingers
possible wasting of thenar eminence due to loss of LOAF
feeling intact in palmar cutaneous branch
What is the motor and sensory distribution of the ulnar nerve?
motor = 1 1/2 muscles in forearm and small muscles of the hand (except LOAF)
Sensory = ulnar half of the hand
What might damage to the ulnar nerve cause?
patial claw hand due to the motor function of the flexor carpi ulnaris and 1 1/2 flexor digitorum profundus (4th and 5th phalange)
Wasting of the hypothenar eminence
wasting of the interossei (inability to hold paper between fingers)
loss of adduction of thumb (compensate with bent 1st distal interphalangeal joint)
How do you test for ulnar nerve damage using the thumb?
you ask them to hold a piece of paper with their thumb - if they compensate by bending their thumb to hold the paper = ulnar nerve damage and loss of the adductor pollicis brevis muscle = froment’s sign
What nerve are we testing by placing paper between the fingers?
we are testing the interossei muscles which are supplied by the ulnar nerve
What is the ‘ulnar nerve paradox?’
a more distal lesion causes greater deformit because the flexor digitorum profundus is still pulling =
What injuries could damage the axillary nerve? What might injury to the axillary nerve cause?
injury to the axillary nerve could be due to shoulder dislocation, fractured surgical neck of humerus, or injections
damage could lead to paralysis of teres minor and the deltoids as well as loss of senstion over the regimental patch
What is erbs paralysis?
it is an upper brachial plexus injury causing the ‘waiter’s tip’ deformity = extension of arm, medial rotation at shoulder, and flexion of the hand
What is Klumpke’s Paralysis?
lower brachial plexus injury from an increased angle between trunk and arm - results in ‘claw hand ‘ from damage to C8-T1
Describe the Sterno Clavicular joint
It is a synovial joint saddle shaped
divided in two by an articular disk
it depends on the costoclavicular ligament
Describe the dermatomes of the hand
anteriorly - radial side = median nerve
- ulnar side = ulnar nerve
posteriorly - radial side = radial nerve
ulnar side = ulnar nerve
Describe the acromioclavicular joint
synovial joint that depends on the coracoclavicular ligament
Describe the wrist joint
synovial joint consists of the distal end of the radius, the scaphoid and the lunate
