Exam 3 - Nerve Lesions of the Upper Limb Flashcards
Loss of which nerve produces seriously weakened abduction and sensory loss in the skin over the lower half of the deltoid muscle?
Axillary nerve!
Note: This nerve can be injured by the pressure of badly adjusted crutches or shoulder joint dislocations.
‘Saturday night palsy’ - caused by falling asleep with arm on the back of a chair - will prevent what function?
Extension of the forearm - by the radial nerve
A fracture of the proximal humerus would cause paralysis of what 3 muscles?
Triceps
Brachioradialis
Supinator
If the supinator muscle is lost, what muscle can still aid in supination
Biceps brachialis is actually the prime supinator
In radial groove injuries that cause radial nerve lesions, what action may still be spared?
Extension of elbow. Branches are given off earlier, so this action is impaired in axilla injuries to the radial nerve.
Which nerve may be injured as a result of supracondylar fractures of the humerus?
Median nerve
With median nerve injuries in the elbow region, which forearm muscles are not paralyzed?
Flexor carpi ulnaris
Medial one-half flexor digitorum profundus
A patient’s forearm is in supine position from paralysis of a particular nerve. What nerve is this?
Median nerve - the forearm is supinated due to the loss of the pronators.
A patient attempts to make a fist, but you notice that his index finger remains straight and the middle finger bends only slightly. What nerve must be damaged?
Median nerve - the ring and little finger bend, but are weakened by the loss of the flexor digitorum superficialis.
Additionally, there is unopposed adduction. The thumb is adducted, which is different from “claw-hand” that occurs with lesions of the ulnar nerve.
Where is the most common site of injury for the median nerve?
Interval between tendons of flexor carpi radialis and flexor digitorum superficialis (overlapped by the palmaris longus tendon).
Note: in wrist injuries of the median nerve, all sensory innervation to hand is lost, and control of hand muscle is lost.
What is the most common compression neuropathy in the peripheral nervous system?
Carpal tunnel syndrome
In carpal tunnel syndrome, why is there no sensory loss over the thenar eminence?
Thenar eminence supplied by the palmar cutaneous branch of the median nerve, which passes superficially to the flexor retinaculum (and before median nerve enters carpal tunnel!)
In peripheral neuropathies, which symptom (sensory or motor) occurs first?
Sensory
In one particular nerve lesion, patients will make a triangle shape with thumb/index when asked to make the “ok” sign. This is caused by weakness of the long flexor muscle of the thumb and the flexor digitorum profundus 1, which are innervated by what nerve?
Anterior interosseous branch of the median nerve
Where is the ulnar nerve commonly injured?
Where it lies behind the medial epicondyle is a common site of injury. If this happens, all muscles innervated by the ulnar nerve are knocked out.
