A text-book of physiology for medical students and physicians . lane. The plane ofeach of the anterior canals isparallel to that of the posterior orinferior vertical canal of the op-posite side, as represented in thefigure. At one end of each canal,near its junction with the utricu-lus, is the swelling known as theampulla, and within the ampullalies the crista acustica, containingthe hair cells with which the nervefibers communicate, and which,therefore, are considered as thesense cells of the organ. The haircells are cylindrical and eachgives off a long hair, consistingperhaps of a bundle of
A text-book of physiology for medical students and physicians . lane. The plane ofeach of the anterior canals isparallel to that of the posterior orinferior vertical canal of the op-posite side, as represented in thefigure. At one end of each canal,near its junction with the utricu-lus, is the swelling known as theampulla, and within the ampullalies the crista acustica, containingthe hair cells with which the nervefibers communicate, and which,therefore, are considered as thesense cells of the organ. The haircells are cylindrical and eachgives off a long hair, consistingperhaps of a bundle of finerhairs, which projects into theinterior of the canal for a distanceof at least 28/^. The nerve fibersdistributed to these hair cells are given off by the vestibular branchof the eighth nerve, or more properly the vestibular nerve, onebranch of which (ramus utriculo-ampullaris) supplies the utriculusand the ampulla of the superior and horizontal canals, while theother (ramus sacculo-ampullaris) furnishes fibers to the sacculusand the posterior ampulla. 397. Fig. 179.—Diagram to show the posi-tion of the semicircular canals in the headof the bird. On each side it will be seenthat the three canals lie in planes at rightangles to one another. The external orhorizontal canals (E) of the two sides liein the same plane. The anterior canal ofone side (A) lies in a plane parallel to thatof the posterior canal (P) of the other side(Ewald). 398 THE SPECIAL SENSES. Flourenss Experiments upon the Semicircular Canals.—Modern experiments and theories concerning the functions of thesemicircular canal date from the classical researches of Flourens*(1824). This investigator laid bare the canals in birds and mam-mals and studied the effects of sections of one or more of experiments have since been repeated by numerous observers,
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