median nerve anatomy, tests, injury

1. Median Nerve
-Siddhant Binyala

2. Median
Nerve
Root value C5,
6, 7, 8 and T1
Arises in the
axilla by 2
roots
-lateral
-medial
(from lateral
cord of brachial
plexus) (from
medial cord of
brachial plexus)

3. In Axilla
• Median nerve is formed by lateral root from
lateral cord and medial root from mdial cord of
brachial plexus
• Median nerve runs lateral to axillary artery

4. In Arm
• Median nerve continues to run on
lateral side of brachial artery till the
middle of the arm, where it crosses
infront of the artery and passes anterior
to the elbow joint into forearm

5. In Forearm
• Enters the forearm between the two heads of pronator
teres
• Then deep to the fibrous arch of flexor digitorum
superficialis in proximal third
• In mid forearm, descends between flexor digitorum
superficialis and flexor digitorum profundus
• About 5 cm above wrist, it coms to lie on the lateral side of
the flexor digitorum superficialis, becomes superficial just
above the wrist

6. In Hand

8. Branches
• In arm- Vascular branches to the brachial
artery
• In forearm- Muscular branches to all
superficial flexor muscles ( pronator teres,
flexor carpi radialis, palmaris longus and
flexor digitorum superficialis)
• Anterior interosseous, that comes off the
median nerve spplies lateral half of flexor
digitorum profundus, flexor pollicis longus
and pronator quadratus
• Articular branches supply the elbow joint
and prximal ulnar joint
• Palmar cutaneous branch supply skin over
thenar eminence and central part of palm

10. Injury to Median nerve
• Most commonly injured at the wrist or high
up in the forearm
• 1) high median nerve palsy
• 2) low median nerve palsy

11. Low median
nerve palsy
• Injury in the distal third of forearm
• Cuts infront of wrist or by carpal dislocation
• There will be sparing of forearm muscles, but
the muscles of the hand will be paralysed
• Thenar eminence is wasted and thumb
abduction and opposition are weak
…

12. High median
nerve palsy
• Injury prximal to the elbow
• Generally due to forearm fractures or elbow
dislocation
• Trauma may damage the nerve at any level
• This will cause paralysis of all muscles
supplied by the median nerve in the forearm
and hand

13. Flexor pollicis longus
• This muscle is tested by holding the
thumb at its base and patient is asked
to bend the terminal phalanx

14. Flexor digitorum
superficialis and
profundus
• Patient is asked to clasp the hands,
index finger of the affected side fails
to reflex
• Oschner.s clasping test

15. Flexor carpi
radialis
The hand deviates to the
ulnar side when its flexed
against resistence

16. Abductor pollicis
brevis
• Patient is asked to lay his hand flat
on the table, a pen is held above the
palm and the patient is asked to
touch the pen with his thumb
• Pen test

17. Opponens pollicis
• Bring the tip of the thumb
towards the tips of other fingers

18. Phelan’s maneuver
• Diagnostic test for carpal tunnel syndrome
• A person holds his forearms horizontally and
then pushes backs of the hands together (inverse
praying position to achieve maximal wrist flexion
)

19. Tinel’s sign
• Tinel’s sign is positive when lightly
percussing over the nerve elicits a
sensation of tingling or ‘pins and
needles’ in the distribution of nerve

20. Carpal compression
test
• Direct pressure over transverse
ligament for 30 seconds
• Onset of pain or paresthesia along the
course of the nerve after 30 seconds
gives a positive result for carpal tunnel
syndrome