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Median nerve: want to learn more about it?

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Median nerve

Median nerve: Origin and course

The median nerve is a branch of the brachial plexus that supplies most of the superficial and deep flexors in the forearm, thenar and lumbrical muscles. It also gives sensation to certain areas of the skin of the hand.

Due to its innervation field, the median nerve enables us to perform both coarse and fine movements of the upper limb. One example is thumb opposition, which is important for precision handling and performing lots of activities like writing, threading a needle or winding a watch.

In this article we will discuss the anatomy and function of the median nerve, as well as the clinical points related to it.

Key facts about the median nerve
Origin Brachial plexus (C6-T1)
Branches Muscular branches, anterior interosseus nerve, articular branches, cutaneous nerve of palm, common palmar digital nerves, reccurent branch
Motor supply - Flexor muscles in the forearm (except flexor carpi ulnaris and the ulnar head of flexor digitorum profundus)
- Muscles of the thenar eminence
- Radial two lumbricals
Sensory supply The skin of the:
- Palmar and distal dorsal aspects of the lateral three-and-the-half digits and adjacent palm
- Palmar and distal dorsal aspects of the thumb and radial half of 2nd digit
- Palmar and distal dorsal aspects of the adjacent sides of 2nd–4th digits
- Central palm
Contents
  1. Origin and nerve roots
  2. Course
  3. Branches and innervation
  4. Clinical notes
    1. Carpal tunnel syndrome
    2. Hand of Benediction
    3. Simian/ape hand deformity
    4. Pronator syndrome
  5. Sources
+ Show all

Origin and nerve roots

The median nerve arises in the axillary region and it is formed by the unification ofthe medial and lateral cords of the brachial plexus. It contains fibres from roots of spinal nerves C6-T1, but in some individuals it can also contain fibers from C5.

Brachial plexus in cadaver: Median nerve seen arising from medial and lateral roots. The roots are recognized as they form an M-structure with musculocutaneous and ulnar nerves over the axillary artery.

Course

After its formation from the brachial plexus, the median nerve descends down the centre of the arm in a superficial course. Initially it is lateral to the brachial artery but as it descends, it eventually becomes medial. 

Just before it enters the forearm, the median nerve passes between the tendons of biceps brachii and brachialis. At this point it again becomes lateral to the brachial artery. Next, in order to gain access to the forearm, it passes between the deep and superficial heads of the pronator teres muscle. Once it passes this point, it dives deeper and runs between the flexor digitorum profundus and flexor digitorum superficialis.

The median nerve then passes through the carpal tunnel beneath the flexor retinaculum, and terminates by dividing into two terminal branches, the common palmar digital nerves.

Dissected carpal tunnel showing median nerve traversing the carpal tunnel with the nine flexor tendons; the flexor pollicis longus, the four flexor digitorum superficialis and the four flexor digitorum profundus.

Branches and innervation

The median nerve gives off numerous branches in the forearm and hand regions. The branches in the forearm region include: 

The major branches in the hand include:

  • The cutaneous nerve of the palm, which supplies the proximal aspect of the palm. This branch does not enter the carpal tunnel and is hence spared in carpal tunnel syndrome.
  • The two common palmar digital nerves, the first of which supplies the radial two lumbricals. The second runs between the ring and middle finger, and divides to give the proper digital nerves that provide sensation to certain areas of the hand. 
  • The recurrent branch to the muscles of the thenar eminence (flexor pollicis brevis, abductor pollicis brevis, opponens pollicis). It is also known as the ‘million dollar nerve’ to signify its importance for basic hand function. 

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To summarize, the median nerve provides the motor supply to the flexor muscles in the forearm, except flexor carpi ulnaris and the ulnar head of flexor digitorum profundus (which is supplied by the ulnar nerve). It also supplies the thenar muscles as well as the radial two lumbricals.

The sensory supply of the median nerve includes:

  • The skin of the palmar and distal dorsal aspects of the lateral three-and-the-half digits and adjacent palm.
  • The skin of the palmar and distal dorsal aspects of the thumb and radial half of 2nd digit.
  • The skin of palmar and distal dorsal aspects of the adjacent sides of 2nd–4th digits.
  • The skin of the central palm.
Hand skin supply: Sensory supply areas of the median, radial and ulnar nerves

Learn more about the median nerve with our video tutorial and quiz:

Median nerve: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

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