Nerve Lesions of the Upper Limb Flashcards
What is caused by lesion of the axillary nerve?
Paralysis of deltoid muscle and teres minor
Loss of cutaneous sensation over lower half of deltoid muscle
What are the two places where the radial nerve can be injured?
Injuries in the axilla
Injuries in the radial groove
What muscles are paralyzed when the radial nerve is injured in the axilla? What joints are affected?
Triceps, brachioradialis, supinator, and all extensors are paralyzed
The elbow joint or the wrist joint cannot be extended
Therefore, wrist drop occurs due to unopposed action of wrist flexors
When the radial nerve is injured in the axilla, what has a loss of sensation?
Down posterior surface of lower part of arm
Down a narrow strip on back of forearm
Lateral part of dorsum of hand
Dorsal surface of the roots of the lateral fingers
What is affected when the radial nerve is injured in the radial groove?
Still have wristdrop
Extension of elbow may be spared (triceps branches are spared)
Loss of sensation on dorsal surface of lateral part of hand and dorsal surface of the roots of the lateral fingers
What is paralyzed if there is a lesion of the median nerve in the elbow region?***
Pronator muscles of the forearm
Long flexor muscles of wrist and fingers (except the flexor carpi ulnaris and medial 1/2 of flexor digitorum profundus)
Thenar muscles of hand
First 2 lumbrical muscles
What are the functional consequences of a median nerve lesion at the elbow?
- Forearm is kept in supine position (loss of pronators)
- Wrist flexion is weak and accompanied by adduction (flexor carpi radialis abducts and is lost)
- No flexion possible at interphalangeal joints of index and middle finger (paralysis of flexor digitorum profundus/superficialis; profundus at lateral 1/2 will be OK because it is innervated by ulnar nerve)
- Hand sign of Papal benediction
- thenar eminence are paralyzed and wasted
- thumb is adducted (loss of flexor pollicis and abductor pollicis thenar muscles)
- inability to oppose thumb (no opponens pollicis)
- loss of skin sensation on lateral half of palm and some on distal part of dorsal surfaces (nailbed area)
What are the functional consequences of a median nerve lesion at the wrist?
- paralysis of thenar muscles and 1st and 2nd lumbricals
- thenar eminence is wasted and flattened
- adducted thumb
- inability to oppose thumb
- sensory loss on lateral half of palm and some on distal part of dorsal surfaces (Nailbed area)
What is the mot common compression neuropathy, and what occurs during it?
Carpal tunnel syndrome (sensory loss first, motor loss second)
- burning pain along distribution of median nerve
- weakness of thenar muscles
- no sensory loss over thenar eminence because this area is supplied by palmar cutaneous branch of median nerve, which passes superficial to flexor retinaculum
What muscles are affected if the anterior interosseous nerve of the median nerve is affected?
- flexor pollicis longus: weakness of long flexor muscle of the thumb
- flexor digitorum profundus: weakness of deep flexor muscles of index and middle finger
- pronator quadratus
What nerve is affected if a patient makes a triangle sign instead of the OK sign?
Anterior interosseous syndrome:
weakness of flexor pollicis longus and flexor digitorum profundus (for lateral 1/2 of flexor digitorum profundus)
-patient will have difficulty picking up small objects from a flat surface
-no sensory loss!
Where is the ulnar nerve in a vulnerable position for damage?
At the elbow, where it lies behind the medial epicondyle
What muscles are paralyzed if the ulnar nerve is injured at the elbow?
- flexor carpi ulnaris
- medial 1/2 of flexor digitorum profundus
- small muscles of hand (except thenar muscles and first 2 lumbricals)
What are the functional consequences of an injury of the ulnar nerve at the elbow?
- weak wrist flexion accompanied by abduction (not addiction, flexor carpi ulnaris is paralyzed)
- flattening of medial part of forearm due to wasting of ulnaris and medial 1/2 of profundus)
- no abduction or adduction of fingers (paralysis of interosseous)
- impossible to adduct the thumb (paralysis of adductor pollicis)
- hyperextension of knuckles (due to unopposed action of extensor digitorum; normally lumbricals 3/4 and interosseous muscles oppose extensor digitorum)
- flexion of interphalangeal joints (due to unopposed flexor digitorum superficialis)
- claw hand
- wasting of muscles in hypothenar eminence
- loss of skin sensation over medial side of hand (palmar and dorsal sides)
What is the only difference between ulnar injury at the elbow versus that at the wrist?
If the injury is at the wrist, clawhand is more obvious because flexor digitorum profundus is not paralyzed and marked flexion of terminal phalanges occurs
