. The anatomy of the human body. Human anatomy; Anatomy. THE TYMPANUM. 671 gree of projection of the aqueduct of Fallopius, which bounds it in front, by that of the promontory, which is below, and by an osseous tongue which passes up to the pyramid behind. Below the fenestra ovahs is the promontory (r, figs. 254, 255), an eminence which corresponds to the first turn of the cochlea, and has three grooves upon its surface, that diverge above and converge below, where they terminate in a common canal, which opens upon the lower surface of the petrous portion of the temporal bone, be- tween the ca
. The anatomy of the human body. Human anatomy; Anatomy. THE TYMPANUM. 671 gree of projection of the aqueduct of Fallopius, which bounds it in front, by that of the promontory, which is below, and by an osseous tongue which passes up to the pyramid behind. Below the fenestra ovahs is the promontory (r, figs. 254, 255), an eminence which corresponds to the first turn of the cochlea, and has three grooves upon its surface, that diverge above and converge below, where they terminate in a common canal, which opens upon the lower surface of the petrous portion of the temporal bone, be- tween the carotid canal and the groove for the internal jugular vein. This canal (ca- nalis tympanicus, Arnold) may be called the canal of Jacobson, because it contains Jacob- son's nerve, a branch given off from the glosso-pharyngeal, which establishes a very re- markable anastomosis between the glosso-pharyngeal and the nervi moUes derived from the vidian and great sympathetic nerves.* The furrows upon the promontory are in- tended to lodge this anastomosis. They are often formed into complete canals. Behind the fenestra ovahs, and opposite its transverse diameter, is a small projection of variable size, called the pyramid {t, figs. 254, 255). There is an opening upon it which is distinctly visible to the naked eye, and makes the pyramid appear tubular. From this opening emerges a small cord (o, fig. 255), the nature of which is not known, but which is called the stapedius muscle. A bristle passed into this opening enters the canal of the pyramid, which canal is generally described as ending in a cul-de-sac, but this is not the case. M. Huguier, prosector of the faculty, has clearly demonstrated, in a series of preparations, that the canal of the pyramid is a long passage, which passes backward and downward below the aqueduct of Fallopius, becomes vertical like the aqueduct, is separated from it only by a thin lamina of bone, communicates with it by a small open- ing, and at length aband
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
