. Quain's elements of anatomy . I THE TYMPANUM. 4sr Below is a larger and more rounded elevation, caused by the projectionoutwards of the first turn of the cochlea, and named the promontory,or tuber coclilecB (fig. 375, ju?) ; its surface is marked by grooves, in whichlie the nerves of the tympanic plexus. Below and behind the promontory, and somewhat hidden by it, isanother aperture named fenestra rotunda, Avliich lies within a funnel-shaped depression (fig. 375,/.r). In the macerated and dried bone thefenestra rotunda opens into the scala tympani of the cochlea ; but, in therecent state, it
. Quain's elements of anatomy . I THE TYMPANUM. 4sr Below is a larger and more rounded elevation, caused by the projectionoutwards of the first turn of the cochlea, and named the promontory,or tuber coclilecB (fig. 375, ju?) ; its surface is marked by grooves, in whichlie the nerves of the tympanic plexus. Below and behind the promontory, and somewhat hidden by it, isanother aperture named fenestra rotunda, Avliich lies within a funnel-shaped depression (fig. 375,/.r). In the macerated and dried bone thefenestra rotunda opens into the scala tympani of the cochlea ; but, in therecent state, it is closed by a thin membrane. Fig. Fig. 375.—Inner wall of the right tyjipanum (G. D. Thane), f The lower end of tlie Eustacliian tube and canal for the tensor tympani is cnt open■obliquely by the saw. M, bristle passed into the opening from the tympanum into themastoid cells ;/o, fenestra ovalis ; f r, fenestra rotunda ; p, promontory ; a F, aqueductof Fallopius, or canal of the facial nerve; , lower end of the processus cochleariformis,•cut; 11, bristle passed through the canal for the tensor tympani muscle; Eu, bristle in theEustachian tube. The membrane closing the fenestra rotunda—secondary memlrane ofthe tympanum (Scarpa)—is rather concave towards the tympanic canity,and, like the membrana tympani, is composed of three structures, themiddle being fibrous, and the outer and inner derived from the mem-branes lining the cavities between which it interposed, viz., thetympanum and the cochlea. The posterior wall of the tympanum has at its upper part one larger(fig. 375, J/), and several smaller openings,
Size: 1557px × 1605px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
