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.
Arc of a Circle. A connected section of the circumference of a circle. Arcs are measured in two ways: as the measure of the central angle, or as the length of the arc itself. Measurement by central angle. (degrees). The red arc (minor arc) measures 120Â°. The blue arc (major arc) measures 240Â°.