Median nerve
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The median nerve is a mixed nerve that arises from the brachial plexus and innervates parts of the arm, forearm, and hand. It is susceptible to compression injuries at the carpal tunnel in the wrist (carpal tunnel syndrome) and between the heads of the pronator teres muscle in the elbow (pronator syndrome). Carpal tunnel syndrome commonly causes pain, numbness, and tingling in the hand and can lead to muscle atrophy if not treated. Non-surgical treatments include splinting and injections while surgical decompression of the carpal tunnel is also an option.
Median nerve
- 2. • Mixed nerve (contain motor & sensory fibers). • Root value: C 5,6,7,8 & T1 • Runs in the median plane of the forearm , so its called median nerve
- 3. • Arises in the axilla by 2 roots (lat &med): 1) lat .root : from the lat . Cord of the brachial plexus 2) med .root : from the med . Cord of the brachial plexus .
- 4. In axilla • Median nerve is formed by lateral root from lateral cord and medial root from medial cord of brachial plexus • Median nerve runs lateral side of axillary artery
- 5. In arm • median nerve continues to run on the lareral side of brachial artery till the middle of arm , where it crosses infront of the artery and passes anterrior to the elbow joint into forearm
- 6. In forearm • Enters to the forearm b/w two heads of pronator teres . • Then deep to fibrous arch of flexor digitorum superficialis , in proximal third • In mid forearm descends b/w flexor digitorum superficialis and flexor digitorum profundus . • About 5 cm above wrist , it comes to lie on the lateral side of the flexor digitorum superficialis , becomes superficial just above wrist
- 8. In hand • Nerve passes deep to the flexor retinaculum and enters the palm • Muscular braches supply muscles of thenar eminence ( abductor pollicis brevis , opponens pollicis and flexor pollicis brevis )
- 9. • Finally divides into 4 to 5 palmar digital branches supplying lateral three and half digit and their nail beds • Also , motor braches are given to the first and second lumbrical muscles
- 10. Branches • In arm : vascular branches to the brachial • In the forearm : muscular branches to all superficial flexor muscles ( pronator teres , flexor carpi radialis , palmaris longus and flexor digitorum superficialis ) Anterior interosseous , which comes off the median nerve supplies lateral half of flexor digitorum profundus , flexor pollicis longus and pronator quadratus
- 11. Articular branches supply the elbow joint and proximal ulnar joint Palmar cutaneous branch supply skin over thenar eminence and central part of palm
- 12. INJURY TO MEDIAN NERVE • Median nerve is most commonly injured near the wrist or high up in the fore arm • Muscles supplied by median nerve affected acc. To level of median nerve injury. 1.High median nerve palsy 2.Low median nerve palsy
- 13. Low median nerve palsy • Injury in the distal third of the forearm • Cuts infront of wrist or by carpal dislocation • There will be sparing of the forearm muscles , but the muscles of the hand will be paralysed • There will be anaesthesia over the median nerve distribution in the hand
- 14. cont • Thenar eminence is wasted and thumb abduction and opposition are weak • Sensation is lost over the radial three and half digits and trophic changes may seen
- 15. High median nerve palsy • Injury proximal to the elbow • Generally due to forearm fractures or elbow dislocation • Stabs and gunshot wounds may damage the nerve at any level • This will cause paralysis of all the muscles supplied by the median nerve in the forearm and hand
- 16. • Muscles examined: • 1) flexor pollicis longus : this muscle is tested by holding thumb at its base and patient asked to bend the terminal phalanx
- 17. • 2) flexor digitorum superficialis and & profundus (lateral half ) …..Ochsner’s clasping test is : when the patient is asked to clasp the hands , the index finger of affected side fail to flex • 3) flexor Carpi radialis : the hand deviate to ulnar side when it is flexed against resistance
- 18. • 4) muscles of thenar eminance • abductor pollicis brevis…….pen test : the 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 • opponens pollicis : brings the tip of the thumb towards the tips of other fingers
- 19. Median nerve compression • Three separate syndromes are recognised 1.Carpal tunnel syndrome 2.Pronator syndrome 3.Anterior interosseous syndrome
- 20. It is compressive neuropathy of median nerve as it passes through the carpal tunnel of the wrist joint.
- 22. causes • Ideopathic - Most common • Inflamatory - Rheumatoid Arthritis - Wrist osteoarthritis • Post traumatic - Bone thickening • Endocrine - Myxoedema - Acromegaly
- 23. • High prevelance rates have been reported in persons who perform certain repetitive wrist motions ( frequent computer users ) • Pregnancy • Gout
- 24. Symptoms and Signs Symptoms include • Pain of the hand and wrist associated with tingling and numbness, classically distributed along the median nerve (the palmar side of the thumb, the index and middle fingers, and the radial half of the ring finger) • Typically, the patient wakes at night with burning or aching pain and shakes the hand to obtain relief and restore sensation. • Thenar atrophy and weakness of thumb opposition and abduction may develop late.
- 25. AtrophyAtrophy
- 26. Physical examination • Phalen’s maneuver
- 27. • Tinel’s sign
- 28. • Carpal compression test
- 30. Treatment • Splinting – prevent wrist flexion • corticosteroid/anesthetic injection – give temporary relief • surgical decompression
- 31. Wearing a lightweight wrist splint especially at night, and taking mild analgesics
- 32. • If symptoms persist or recur or if hand weakness and thenar wasting develop, the carpal tunnel can be surgically decompressed by using an open surgical division of the transverse carpal ligament
- 34. Complications of surgery • Injury to palmar or cutaneous or recurrent motor branch of the median nerve • Hypertrophic scarring • Hematoma • Artery injury
- 35. Pronator teres syndrome • Pronator teres syndrome is a compression neuropathy of the median nerve at the elbow between heads of pronator teres • It is rare compared to compression at the wrist (carpal tunnel syndrome) or isolated injury of the anterior interosseous branch of the median nerve (anterior interosseous syndrome).
- 36. • Symptoms are similar to those of carpal tunnel syndrome , although night pain is unusual and forearm pain is more common • phalen’s test obviously be negative • Symptoms can be provoked by resisted elbow flexion with forearm supinated ( tightening of bicipital aponeurosis ) • By resisted forearm pronation with the elbow extended ( pronator tension )
- 37. • Tinel’s sign may be positive over the nerve proximally but not at carpal tunnel
- 38. Anterior interosseous syndrome Is a medical condition in which damage to the anterior interosseous nerve, a motor branch of the median nerve, causes pain in the forearm and a characteristic weakness of the gripping movement of the thumb and index finger.( unable to make ok sign ) • Most cases are due to compression of the nerve as a result of trauma at the elbow, often associated with haemorrhage into the deep musculature.
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