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(rĕt″ĭ-năk′ū-lŭm) pl. retinacula [L., halter] A band or membrane holding any organ or part in its place. Thickenings of the deep fascia in distal portions of limbs that hold tendons in position when muscles contract are called retinaculum tendinum.

r. cutis A fibrous band connecting the corium with underlying fascia.

extensor r. of ankle 1. The superior extensor retinaculum, a band crossing the extensor tendons of the foot and attached to the lower portion of the tibia and fibula. 2. The inferior extensor retinaculum, a band located on the dorsum of the foot. It consists of two limbs having a common origin on the lateral surface of the calcaneus. The upper limb is attached to the medial malleolus; the lower limb curves around the instep and is attached to the fascia of the abductor hallucis on the medial side of the foot.

extensor r. of wrist An oblique band attached medially to the styloid process of the ulna, the hamate bone, and the medial ligament of the wrist joint. Laterally it is attached to the anterior border of the radius. It contains six separate compartments for passage of the extensor tendons to the hand.

flexor r. of ankle The retinaculum extending from the medial malleolus to the medial tubercle of the calcaneus.

flexor r. of hand The fascial band that holds down the flexor tendons of the digits.

flexor r. of wrist The retinaculum extending from the trapezium and scaphoid bones laterally to the hamate and pisiform bones medially.

r. of hip joint Any of three flat bands lying along the neck of the femur and continuous with the capsule of the hip joint.

patellar r. One of two fibrous bands (medial and lateral) lying on either side of the knee joint and forming part of the joint capsule. These bands are extensions of the insertions of the medial and lateral vastus muscles of the thigh.

peroneal r. One of two fibrous bands on the lateral side of the foot that contains the tendons of the peroneus longus and brevis muscles. The superior peroneal retinaculum extends from the lateral malleolus to the lateral surface of the calcaneus; the inferior peroneal retinaculum is attached below to the calcaneus and above to the lower border of the inferior extensor retinaculum.

r. tendinum The annular band of the wrist or ankle.


(rĕt′ĭ-năl) 1. Pertaining to the retina. 2. The light-absorbing portion of a photopigment, a derivative of vitamin A.

retinal break

A break in the continuity of the retina, usually caused by trauma to the eye. Detachment of the retina may follow the appearance of the break.


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