Semicircular ducts
Ductus semicirculares
Definition
The semicircular ducts are about one-fourth of the diameter of the osseous canals, but in number, shape, and general form they are precisely similar, and each presents at one end an ampulla.
They open by five orifices into the utricle, one opening being common to the medial end of the superior and the upper end of the posterior duct.
In the ampullæ the wall is thickened, and projects into the cavity as a fiddle-shaped, transversely placed elevation, the septum transversum, in which the nerves end.
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