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.
Definition of Minor Arc. Minor Arc is smaller of the two arcs formed when a circle is divided into two unequal parts. 1  The measure of the minor arc is always less than 180Â° or Ï radian.