Recurrent branch of median nerve
The recurrent branch of median nerve (C8, T1) is a small muscular branch given off by the median nerve (C6-T1) to supply the thenar eminence in the hand. It is a purely motor nerve. While recurrent branch of median nerve is the official anatomical term, variant terminology can be found in textbooks. Synonyms include recurrent motor branch of median nerve, recurrent median nerve, thenar muscular branch and million dollar nerve.
As a nerve arising from the brachial plexus, the median recurrent nerve reaches the hand by traveling through the carpal tunnel. Also known as the transverse carpal ligament, the carpal tunnel lies deep to the flexor retinaculum and acts as a passageway for the forearm structures to reach the hand. These structures include the median nerve along with the nine tendons of the forearm muscles: more specifically four tendons of flexor digitorum superficialis, four tendons of flexor digitorum profundus and a single tendon of flexor pollicis longus muscle.
Anatomical variations in the branching pattern of the recurrent branch of median nerve are fairly common. The Poisel classification is often used to describe the course and variations of the nerve’s branches as well as their relationship to the transverse carpal ligament. This classification divided the variations into three types:
- Extraligamentous type: recurrent branch of median nerve arises close to the distal end of the transverse carpal ligament and continues a retrograde course to reach the thenar eminence.
- Subligamentous type: recurrent branch of median nerve arises within the carpal tunnel and maintains its course deep to the transverse carpal ligament to reach the thenar eminence.
- Transligamentous type: recurrent branch of median nerve arises within the carpal tunnel and proceeds to pierce the transverse carpal ligament to reach the thenar eminence.
Owing to its subcutaneous location, the recurrent branch of median nerve can be easily severed when this area is lacerated resulting in paralysis of the thenar muscles. Colloquially, the nerve is also known as the ‘million dollar nerve’. Iatrogenic injury to the nerve during surgery can lead to a ‘million dollar lawsuit’ due to loss of basic hand function.
Terminal branches of the recurrent branch of median nerve supply the thenar eminence, the fleshy prominence of the thumb. Specific muscles innervated by the nerve are the abductor pollicis brevis, opponens pollicis and the larger superficial head of the flexor pollicis brevis.
In order to remember the muscles innervated by the recurrent branch, you can use the mnemonic LOAF to recall the motor innervation of the median nerve. This stands for:
- L: lateral two lumbricals
- O: opponens pollicis
- A: abductor pollicis brevis
- F: flexor pollicis brevis (superficial head)
|Terminology (variations)||Recurrent branch of median nerve
Variations: recurrent motor branch of median nerve, recurrent median nerve, thenar muscular branch, million dollar nerve
|Definition||The median recurrent nerve (C8, T1) is a small motor branch given off by the median nerve (C6-T1).|
|Field of innervation||Abductor pollicis brevis muscle, opponens pollicis muscle and superficial head of flexor pollicis brevis muscle|
|Function||Motor innervation of thenar muscles|
Learn more about the intrinsic muscles of the hand with this study unit:
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