Common synovial sheath for the flexor tendons

The common synovial sheath for the flexor tendons is a synovial sheath in the carpal tunnel.

It contains tendons of the flexor digitorum superficialis and the flexor digitorum profundus, but not the flexor pollicis longus.

The sheath which surrounds the Flexores digitorum extends downward about half-way along the metacarpal bones, where it ends in blind diverticula around the tendons to the index, middle, and ring fingers. It is prolonged on the tendons to the little finger and usually communicates with the mucous sheath of these tendons.