Final answer:
The Crista ampullaris refers to the mound of hair cells and supporting cells located within the ampullae of the semicircular ducts, which is essential for the vestibular system to sense rotational movement of the head.
Step-by-step explanation:
The term referring to the mound of hair cells and supporting cells within the ampullae of the semicircular ducts is the Crista ampullaris.
The mound of hair cells in the ampullae of the semicircular ducts is known as the Crista ampullaris.
The ampulla is an enlargement at the base of the semicircular canals of the vestibular system, integral for detecting rotational movements of the head such as turning side to side. The Crista ampullaris is the structure within the ampulla that contains the sensory hair cells, which extend their stereocilia into a gel-like dome-shaped membrane called the cupula. When the head rotates, the fluid within the semicircular canals moves, and this movement is sensed by the deflection of the cupula.
This deflection then stimulates the hair cells, which convert the mechanical movement into electrical signals that are interpreted by the brain as motion, contributing to our sense of balance and spatial orientation. This sensory mechanism differs from that of the utricle and saccule which utilize macula tissue containing otoliths for detecting linear acceleration such as gravity.