Anatomy word of the month: retinaculum

A “cord or cable” in Latin. Retinacula are thickenings of tissue underneath your skin that serve to bind down tendons of muscles so they don’t “bowstring” at certain joints, meaning pop up when the joint is flexed or extended. For example, there is a retinaculum on the underside of your wrist that keeps tendons from popping up when you flex or bend your hand at the wrist. But, you may have noticed that there is distinct cord that becomes prominent when you bend your wrist. Hold on to the fingers of your right hand and attempt to bend your wrist against resistance. You likely will see a distinct cord pop up in the middle of your wrist. One of the muscle tendons at the wrist, the palmaris longus, “the long muscle of the palm”, is outside of the retinaculum, that is, not bound down. If you don’t see this cord in one or the other of your wrists, don’t be upset! It is missing in a portion of the normal population.

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