Final answer:
The crista ampullaris located in the semicircular duct is not essential for detecting static equilibrium. The utricle and saccule are responsible for sensing straight-line acceleration and gravity.
Step-by-step explanation:
The crista ampullaris located in the semicircular duct is not essential for detecting static equilibrium. The crista ampullaris is responsible for detecting rotational movements of the head, such as turning the head from side to side. Static equilibrium, on the other hand, is maintained through sensors called utricle and saccule, which are responsible for sensing straight-line acceleration and gravity.