Like all elements that are part of the posterior labyrinth, we distinguish between the osseous and membranous semi-circular canals, the former protecting the latter.

- Osseous semi-circular canals
There are three semi-circular canals along all three plains. They form a bony curl that opens into the vestibule. There is one exterior canal, horizontal, and two 2 vertical canals, the superior and posterior.
 
- Membranous semi-circular canals
Connecting with the utricle, the membranous semi-circular canals are contained within their osseous homologues and are bathed in perilymph.
With a diameter four times smaller, they contain endolymph and where they connect to the utricle, there is reception structure, the ampullary crest. The ampullary crest is sheltered behind a bulge in the canal called the ampulla.