the otic capsule, situated in the very depths of the skull around the inner ear. This is part of the petrous temporal bone, which houses the cochlea, the organ of hearing, and the semi-circular canals responsible for balance. As the inner ear forms in the embryo and fetus, it does so to full adult size immediately and remains insulated against growth and remodelling through the production of high levels of osteoprotegerin (OPG), a basic glycoprotein that suppresses bone turnover.
