. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 562 COMPARATIVE PHYSIOLOGY. muscle, but a supporting ligament for the malleus. The stape- dius, however, has the important function of regulating the movements of the stapes, so that it shall not be too violently driven against the membrane covering the fenestra ovalis. The two muscles, stapedius and tensor, suggest the accom- modative mechanism of the iris. The motor nerve of
. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 562 COMPARATIVE PHYSIOLOGY. muscle, but a supporting ligament for the malleus. The stape- dius, however, has the important function of regulating the movements of the stapes, so that it shall not be too violently driven against the membrane covering the fenestra ovalis. The two muscles, stapedius and tensor, suggest the accom- modative mechanism of the iris. The motor nerve of the sta- pedius is derived from the facial; of the tensor, from the tri- geminus through the otic ganglion. The ButaohUui Tube.âManifestly, if the middle ear were closed permanently, its air would gradually be absorbed. The drum-head would be thrust in by atmospheric pressure, and become useless for its vibrating function. The Eustachian tube, by communicating with the throat, keeps the external and internal pressure of the middle ear balanced. Whether this canal is permaneutiy open, or only during swallowing, is as yet undetei* Fio ,««.âDiagmm inteBdcd to lUmtnte the procMMS of heiirinff (after IfndoW â AO, exfenid auditory meatn*; T, tympanic "wi"**"*: «i,««^«! «⢠*5»2^fv2Sl die oar: o. fenestra ovalta; r, feneetra rotni^; »f,,ecaja tympanl; ««. â¢Â«Â»Â»Â»â¢â¢Â»â¢ bull; tveeUbnle; S,-ein\ex R utricle; i?, lymlclrento crtwe;r^Bajtochto tube, long arrow Indicate* line of traction of tenww tympani; abort cnrred one tbat of Stapedina. One may satisfy himself that the middle ear and pharynx communicate, by closing the nostrils and then distending the upper air-passages by a forced expiratory effort, when a sense of distention within the ears is experienced, owing to the rise of atmospheric pressure in the Please note that these images are extracted from scanned page images that may hav
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