Lower Extensor Tendon Retinaculum

The inferior extensor tendon retinaculum (retinaculum musculorum extensorum inferius, pna) is a transverse fibrous plate located on the dorsum of the wrist joint. It holds the extensor tendons of the fingers and hand in place, preventing them from moving laterally when moving the wrist and fingers.

The inferior retinaculum of the extensor tendons is formed by transverse fibers of the fascia of the forearm. It attaches laterally to the ulna and medially to the radius. Under it pass the tendons of the extensor muscles of the fingers and hand - the extensor muscles of the fingers, the ulnar muscle of the hand, and the abductor pollicis longus muscle.

The lower extensor tendon retinaculum stabilizes the tendons during movements of the hand and fingers, preventing them from moving. It is important for coordination and strength of movements of the hand and fingers. Damage to the retinaculum can lead to dysfunction of the hand.

**Tendon retinaculum** is a fibrous thickening that covers the inner side of the elbow joint in the region of its posteromedial edge and prevents extension of the hand from the elbow joint. On the medial surface, the extensor retinaculum is covered with hyaline cartilage. It splits in the center and thereby forms two grooves in which the tendons of the thumb and index extensor fingers, as well as the tendon of the vermiform process of the extensor digitorum muscle, pass.

In humans, already during the period of intrauterine development, the retinaculum of long muscles is formed - pars tendinea musculi extensoris superioris. However, the retinaculum of the inferior extensor tendon is not normally inserted. During the process of growth and development of the child, the pars tendinaris musculi extensoris inferior begins to form from part of the former tendon of the posterior root of the radial nerve. It surrounds three tendons - the I2 digital digitorum, the extensor digitorum minor and the flexor digitorum profundus, which lie at the inferior radius. When the carpal joint is formed by the age of fourteen, the retinaculum is in its place. In men, on average, it is located two and a half centimeters below the point of application of the radius bone in relation to the metacarpal bone. In women of this age, the tendons of the hand are more often located at this level, which leads to the ability to rotate the hand outward in a position of pronation of the hand