The posterior semicircular canal (canalis semicircularis posterior) is vertical and directed backward, nearly parallel to the posterior surface of the petrous bone; it is the longest of the three semicircular canals, measuring from 18 to 22 mm.; its lower end is ampullated (Posterior bony ampulla) and opens into the lower and back part of the vestibule, its upper into the crus commune with the anterior semicircular canal.

This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from


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