Anatomy

Physes

In the hand these are located distally in the 2nd to 5th metacarpals, and proximally in the thumb metacarpal and phalanges.

Flexor pulleys

Fingers

In the fingers the flexor pulleys facilitate sheath collapse and expansion during digital motion. There are five annular pulleys: A2 and A4 pulleys originate from bone and it is critical to preserve them to prevent bowstringing of the flexor tendons; A1, A3 and A5 originate from the volar plates. A1 pulley is released in trigger finger.

Three cruciate pulleys are not critical for flexor function. C1 is distal to the A2 pulley over the proximal phalanx; C2 and C3 are either side of the A4 pulley over the middle phalanx.

Thumb

In the thumb there are two annular pulleys and one oblique pulley. The oblique pulley is most important. A1 overlies the MCP joint, attached to the volar plate. A2 overlies the IP joint, attached to the head of PP. The oblique pulley overlies the shaft of PP. The tendon of adductor pollicis attaches to the A1 and oblique pulleys.

Vinculae

The vinculae are folds of mesotendon carrying blood supply to both tendons from transverse branches of the digital arteries. There is a short vinculum (vinculum brevis) and a long vinculum (vinculum longus) to each FDP and FDS tendon. The vincular system is supplied by the transverse communicating branches of the common digital artery. Nutrition of the tendons is also derived from diffusion through the synovial fluid.