median nerve Flashcards
what cords of the brachial plexus form the median nerve?
lateral (musculocutaneous)
posterior (axillary & radial)
median (ulnar)
C5 - T1
what does the sensory terminal branches of the median nerve supply?
thumb
index finger
middle finger
lateral half of ring finger
what does the recurrent (motor) branch of terminal median nerve supply?
(LOAF)
lateral 2 lumbricals
oppenens pollicis
abductor pollicis brevis
flexor pollicis brevis
what superficial flexors does the median nerve supply?
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor digitorum
superficialis
NOT flexor carpi ulnaris
where does the median nerve pass through to enter lower brachium?
pronator teres
where does ulnar nerve enter lower brachium?
flexor carpi ulnaris
where does radial nerve enter lower brachium?
supinator
what 7 muscles are innervated by the median nerve?
pronator teres
flexor carpi radialis
palmaris longus
flexor digitorum profundus
pronator quadratus
flexor pollicis longus
flexor digitorum
superificialis
what cutaneous areas in the hand does the median nerve innervate?
palmar side of thumb
index finger
middle finger
half of ring finger
what structures pass through the carpal tunnel?
median nerve
4 superficial flexor tendons
4 deep flexor tendons
flexor pollicis longus tendon ( most radial)
why is feeling preserved in the hand with carpal tunnel syndrome
palmar cutaneous nerves runs over flexor retinaculum to supply palm of hand, APB, FPB, and OP, 1st & 2nd lumbricals
what is the sign of benediction?
injury to median nerve at level of elbow or upper arm results in inability to flex DIP of index finger due to loss of innervation of lateral half of flexor digitorum profundus
all muscles of the forearm are supplied by median nerve except for ?
half of flexor digitorum profundus
what is the OK sign?
grossly verifies integrity of median nerve, specifically testing anterior interosseous nerve.
paralysis of flexor pollicis longus and flexor digitorum profundus (cannot flex PIP joint) cannot perform
what structure above the elbow can compress the median nerve?
1% population have medial supracondylar spur ( 5 cm proximal to medial epicondyle). together with ligament of struthers can compress median nerve.
describe presentation of pronator teres syndrome
parasthesia in radial 3.5 fingers
weakness in thenar muscles
dull aching pain over proximal forearm
no night symptoms
pronator teres tender to palpation
symptoms ++ with repetitve or forceful pronation
sensory disturbance to palm of hand & thenar muscles
what structures are involved in pronator teres syndrome
in forearm (elbow) median nerve runs btn 2 heads of pronator teres muscle and then flexor digitorum superificialis & profundus; compressing median nerve
what otho tests can help identify pronator teres syndrome
resisted pronation with elbow extension (tests compression btn 2 heads of pronator teres)
resisted elbow flexion with supination of forearm (test for compression at bicipital aponeurosis)
resisted contraction of FDS to middle finger (compresses FDS arch)
2 differential diagnoses for pronator teres syndrome
c 5/6 radiculopathy
carpal tunnel syndrome
what is the differentiating criteria in the hand between pronator teres and carpal tunnel syndrome
no symptoms are present when tinels performed at wrist for PTS
PTS causes thumb and index finger flexion weakness
both have weakness in thenar muscles
CTS has exacerbation of symptoms at night where PTS doesnt
