. The anatomy of the horse, a dissection guide. Horses. THE EAR. 277 into the neck of the stapes. Its tendon of insertion contains a small nucleus of bone. Action.—To regulate the movements (diminish the excursions) of the stapes. Blood-vessels. 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 a
. The anatomy of the horse, a dissection guide. Horses. THE EAR. 277 into the neck of the stapes. Its tendon of insertion contains a small nucleus of bone. Action.—To regulate the movements (diminish the excursions) of the stapes. Blood-vessels. 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 ty7npanic 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 2' 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 divi- sions : the vestibule, the cochlea, and the semicircular canals, and each of these .contains a division of the membranous labyrinth. The Vestibule. This is the 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 fi^ openings. On its outer wall, which separates it from the tympanum, is the fenestra ovalis, closed by the base of the stapes. On its inner wall in front there is a depression—the fovea hemispherica—])\aced over the meatus auditorius internus, and pierced by minute foramina for the passage of the filaments of the au
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecthorses, bookyear1902
