Anatomy of the Volar side of the Wrist

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

• The volar aspect of the wrist includes the radius and ulna.
• The carpal bones are the scaphoid, leonate, triquetrum, pisiform, trapezium,trapezoid,capitate,hamate.
• An important structure in the volar aspect of the wrist is the Carpal tunnel.

Boundaries of the carpal tunnel:

• Carpal bones dorsally and flexor retinaculum and transverse carpal ligament volarly.
• The transverse carpal ligament is attached from scaphoid tubercle and trapezium radially to the hook of the hamate and pisiform ulnarly.

Structures within the carpal tunnel:

Median nerve and nine flexor tendons:
1)Flexor pollicis longus
2)Flexor digitorum superficialis(four tendons)
3)Flexor digitorum profundus(four tendons)

Radial to carpal tunnel is the flexor carpi radialis and radial artery.

The flexor carpi radialis lies radial to the median nerve. The tendon of Palmaris longus is ulnar to the median nerve. Medial to carpal tunnel ,is the ulnar artery,the ulnar nerve and the flexor carpi ulnaris from lateral to medial. Apart from the contents of carpal tunnel we also find thenar muscles,the hypothenar muscles and the guyon’s canal.

Anatomy of Guyon’s canal-It is a tunnel for the ulnar nerve.

Boundaries of Guyon’s canal :

• Floor: Transverse carpal ligament(roof of carpal tunnel)
• Radial border: Hook of hamate
• Ulnar border : Pisiform and Pisohamate ligament.
• Roof: Volar carpal ligament.

One can find the ulnar artery radially and the ulnar nerve medially.

The palmar cutaneous branch of median nerve arises about 6 cm proximal to the wrist and passes superficial to the transverse carpal ligament.The median nerve gives an important branch called the recurrent motor branch of the median nerve.

The recurrent motor branch of the median nerve has multiple variations of the nerve in the carpal canal.It includes extra ligamentous (50,soft ligamentous (30%)and transligamentous(20%).