. The anatomy of the horse, a dissection guide. Horses. THE EAB. 269 the back of the tympanum. Issuing from the pyramid, it is inserted into the neck of the stapes. Its tendon of insertion contains a small nucleus of bone. Action.—To regulate (diminish the excursions of) the movements of the stapes. Bloodvessels. The arteries of the tympanum are derived from the tympanic artery, a branch of the internal maxillary artery. Nerves. The chorda tympani branch of the 7th nerve enters the cavity of the tympanum from the aqueduct of Fallopius; and passing across the membrana tympani it leaves the cavi
. The anatomy of the horse, a dissection guide. Horses. THE EAB. 269 the back of the tympanum. Issuing from the pyramid, it is inserted into the neck of the stapes. Its tendon of insertion contains a small nucleus of bone. Action.—To regulate (diminish the excursions of) the movements of the stapes. Bloodvessels. The arteries of the tympanum are derived from the tympanic artery, a branch of the internal maxillary artery. Nerves. The chorda tympani branch of the 7th nerve enters the cavity of the tympanum from the aqueduct of Fallopius; and passing across the membrana tympani it leaves the cavity by the styloid fora- men. The sensory nerves of the tympanum are derived from the tympanic branch (Jacobson's nerve) of the glosso-pharyngeal. The Nerve to the Stapedius is a branch of the 7th. The Nerve to the Tensor Tympani comes from the 5th, through the otic ganglion. THE INTERNAL EAR. The Internal Ear, called also, from its complexity, the Labyrinth, consists of a series of chambers, or passages, in the petrous temporal bone, and of certain fluids and soft textures contained within these passages. The chambers, with the wall of condensed bone tissue which immediately surrounds them, con- stitute the osseous labyrinth; the contained soft structures form the membranous labyrinth. The osseous labyrinth consists of three divisions; —^the vestibule, the cochlea, and the semicircular canals, and each of these contains a division of the mem- Diagram oi'the Membeaiious Laeybinih. , DC. Ductus coclilearis ; dr. Ductus reuniens ; branOUS labyrinth. S. Saoculus; U. Utriculus ; dv. Ductus vesti- „, -rr rri,;„ Jc +V,q bull; SC. Semicii-cular canals. (Turner, uttei The Vestibule. This is the ^„j^,j^er). central division of the labyrinth. It lies between the inner wall of the tympanum and the internal audi- tory meatus. In front it communicates with the scala vestibuli of the cochlea, and the semicircular canals open into it behind by five openings. On its outer wall, which
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Keywords: ., bookcentury1800, bookdecade1880, booksubjecthorses, bookyear1884
