plexor

Plexor is a term used in clinical examination to denote the hammer component of a reflex hammer. It is used to elicit deep tendon reflexes by delivering a brief, controlled impulse to a surface placed on the skin over a tendon, known as the pleximeter.

A typical plexor consists of a handle and a striking head, often metal with a rubber or plastic striking surface. During examination, the pleximeter is placed on the target area (for example over the patellar tendon) and the clinician rapidly strikes it with the plexor to evoke a reflex.

Common targets include the knee-jerk (patellar) reflex, ankle reflex, and reflexes of the upper limb such as the biceps and brachioradialis. A crisp, quick strike with the hammer, while keeping the limb relaxed, yields the most reliable response.

Plexor is used alongside the pleximeter, the surface struck by the instrument. The term is standard in neurology and medical physiology, with variants in head shapes and materials, including plastic, rubber, and stainless steel. See also reflex hammer, neurological examination, and deep tendon reflex.