Anatomy Of The Median Nerve - Everything You Need To Know - Dr. Nabil Ebraheim

Dr. Ebraheim’s educational animated video describes the anatomy of the median nerve.
The median nerve originates from the lateral cord and the medial cord of the brachial plexus.
The median nerve runs down the arm where it passes on the medial side of the arm between the brachialis and the biceps brachii. The median nerve does not give branches in the “axilla” or in the upper arm.
About 1% of patients have a medial supracondylar humeral spur about 5 cm proximally t the medial epicondyle. The median nerve can become compressed by the supracondylar spur.
At the elbow region the median nerve moves into the area of the cubital fossa. Structures at the elbow from medial to lateral:
Median nerve
Brachial artery
Biceps tendon
The bicipital aponeurosis lies on top of the median nerve. The median nerve is medial to the brachial artery and the biceps tendon. The median nerve is on top of the brachialis and pronator teres muscle is medial.
The median nerve passes under three tunnels including, the bicipital aponeurosis, the pronator teres and the flexor digitorum superficialis. At the cubital foss, the median nerve gives branches to four muscles:
1-Pronator teres
2-Flexor carpi radialis
3-Palmaris longus
4-Flexor digitorum superficialis
The median nerve leaves the elbow region and enters the forearm between the two heads of the pronator teres muscle. The median nerve branches as it courses through the forearm. The median nerve descends between the flexor digitorum superficialis and the flexor digitorum profundus proximally. The nerve becomes superficial distally and is located between the flexor carpi radialis and the palmaris longus. Here the nerve can become easily injured or blocked by anesthesia.
About half the way down the forearm, the anterior interosseous nerve exits from the dorsal lateral aspect of the median nerve. The anterior interosseous nerve is purely motor. All the muscles in front of the forearm are supplied by the median nerve except the medial half of the flexor digitorum profundus. The anterior interosseous nerve gives branches to three muscles:
1-Pronator quadratus
2-Lateral half of the flexor digitorum profundus
3-Flexor pollicis longus
The patient will be unable to do the OK sign due to paralysis of the flexor pollicis longus and the flexor digiorum profundus muscles. Patient cannot flex the PIP joint.
Injury to the median nerve at the level of the elbow or upper arm often results in a deformity know as the hand of the benediction. The median nerve gives the palmar cutaneous branch about 3 cm above the wrist which gives innervation to the radial part of the palm. It descends over the flexor retinaculum to supply the palm of the hand:
1-Thenar group: APB, FPB, OP
2-1st & 2nd lumbricals.
At the wrist, the median nerve becomes superficial distally between the flexor carpi radilais and the palmaris longus and then enters the carpal canal under the transverse carpal ligament. The median nerve ends in the carpal tunnel by giving the recurrent thenar motor branch and dividing into two terminal divisions which are radial and ulnar. The recurrent thenar motor branch gives innervation to the abductor pollicis brevis, the superficial head of the flexor pollicis brevis and the opponens pollicis muscle.
The radial division of the median nerve then divides into three digital branches which supply the two sides of the thumb and lateral side of the index finger and also supplies the first lumbrical.
The ulnar division of the median nerve divides into common digital nerves that supply the second and third web space providing sensation to the adjacent sides of the index and middle finger and the middle and the ring finger. The ulnar division also gives innervation to the second lumbrical muscle.
The median nerve innervates the skin on the palmar side of the thumb, the index finger, the middle finger and half of the ring finger.
The median nerve may become compressed it passes through the wrist and this causes carpal tunnel syndrome.
Surgery for carpal tunnel syndrome is done by releasing pf the transverse carpal ligament.
The median nerve is the most superficial structure accompanied by nine tendons in the carpal tunnel. There are four superficial flexor tendons and four deep flexor tendons within the carpal canal of the hand. The flexor pollicis longus tendon is the most radial.

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