ampullaris

Ampullaris is a Latin term meaning 'of the ampulla' and is used in anatomy to describe structures that form a dilated sac or enlargement at the end of a canal or duct. The most familiar use is in the inner ear, where each of the three semicircular canals ends in an expanded region called an ampulla. There are three ampullae corresponding to the anterior, posterior, and lateral canals. The ampulla houses the sensory epithelium known as the crista ampullaris, which contains hair cells embedded in a gelatinous cupula. When the head rotates, the movement of endolymph deflects the hair bundles, sending signals via the vestibular portion of the eighth cranial nerve to brainstem centers that regulate balance and eye movements.

In the male reproductive tract, the ductus deferens has an enlarged segment known as the ampulla (ampulla ductus deferentis). This structure stores sperm and participates in ejaculation by contributing to the formation of the ejaculatory duct.

The term ampullaris is used more broadly to denote similar dilations in other parts of the body, and the word itself is derived from Latin ampulla, meaning a bottle or flask. In embryology and comparative anatomy, ampullae and their derivatives share the same basic plan: a tubular duct or canal that widens at its end to form a functional sensory or storage region.