Disc degeneration, due to the natural wear and tear of aging, is the most common cause of neural foraminal narrowing. Narrowing of the foramen may also be due to rheumatoid arthritis, osteoarthritis, chronic meningitis or tumors in the spinal column. Less often, the condition is congenital, or present at birth.
in human nervous system: Reflex actions. The anatomical pathway of a reflex is called the reflex arc. It consists of an afferent (or sensory) nerve, usually one or more interneurons within the central nervous system, and an efferent (motor, secretory, or secreto-motor) nerve. Read More.
a method of testing the patency of reflex arc. The tendon is stretched sharply by tapping it close to its insertion. A positive reaction is a sharp contraction of the muscle of which the tendon is part. The patellar reflex is the best known of these reflexes.