Annular ligaments of fingers

Annular Ligaments of Fingers

Illustration of the annular ligaments of fingers

The Annular Ligaments of Fingers are a set of ligaments found in the human hand. They are part of the flexor tendon sheath and play a crucial role in the movement and flexibility of the fingers.

Anatomy

The annular ligaments, also known as A1 to A5 pulleys, are five fibrous bands that encircle the flexor tendons of the fingers. They are named for their ring-like structure, with "annular" deriving from the Latin word annulus, meaning ring.

The A1 pulley is located at the base of the finger, the A2 pulley is found in the proximal phalanx, the A3 pulley is located at the level of the proximal interphalangeal joint, the A4 pulley is found in the middle phalanx, and the A5 pulley is located at the distal interphalangeal joint.

Function

The primary function of the annular ligaments is to hold the flexor tendons close to the bones of the fingers, allowing for efficient finger flexion. They also prevent bowstringing of the tendons during finger flexion, which would otherwise limit the range of motion and strength of the fingers.

Clinical Significance

Injury to the annular ligaments can result in a condition known as trigger finger, where the finger or thumb gets stuck in a bent position. This condition is caused by inflammation or swelling of the flexor tendon sheath, which narrows the space within the sheath and makes it difficult for the tendon to glide smoothly.

See Also

• Flexor tendon sheath
• Trigger finger
• Hand anatomy