A manual of anatomy . kincontinued from the pinna and in it are found the ceruminous, orwax glands {glandulce ceruminosce) and many hairs {barbula hirci). THE MIDDLE EAR The middle portion, or tympanum {cavum tympani) consists of thetympanic cavity proper, the attic, the membrana tympani, the ossiclesand its connection with the pharynx, the auditory tube. 350 THE TYMPANIC CAVITY 351 The tympanic cavity proper, or atrium lies just medial tothe tympanic membrane and is a narrow space, quadrilateral inshape. It is placed practically parallel to the sagittal plane of thebody. Its length and height
A manual of anatomy . kincontinued from the pinna and in it are found the ceruminous, orwax glands {glandulce ceruminosce) and many hairs {barbula hirci). THE MIDDLE EAR The middle portion, or tympanum {cavum tympani) consists of thetympanic cavity proper, the attic, the membrana tympani, the ossiclesand its connection with the pharynx, the auditory tube. 350 THE TYMPANIC CAVITY 351 The tympanic cavity proper, or atrium lies just medial tothe tympanic membrane and is a narrow space, quadrilateral inshape. It is placed practically parallel to the sagittal plane of thebody. Its length and height are 15 mm. each. The distancebetween the lateral and medial walls varies; at the top it is 6 mm., inthe middle about 2 mm. and at the bottom about 4 mm. Above thelevel of the tympanic membrane the tympanic cavity forms a recesscalled the attic {recessus epitympanicus), or epitympanum. Thisrecess contains most of the incus and half of the handle of the mal-leus and communicates with the mastoid antrum. In the anterior. Fig. 255.—Vertical section through the external auditory canal and tympanum. A,Epitympanic recess; B, tympanum; C, fenestra ovalis closed by foot of the stapes; Mem.,tympanic membrane. wall {paries carotica) of this cavity are two openings; the upperrepresents the orifice of the canal that transmits the tensor tympanimuscle {semicanalis m. tensoris tympani) while the lower representsthe orifice of the auditory tube. The medial wall {paries labyrinthica)has an oval opening, the fenestra vestibuli; its long axis, 3 mm., isdirected horizontally while its shorter axis is directed vertically andmeasures about mm. In the recent state this ofjening is closedby the foot of the stapes held in position by the annular ligament{ligamentum annulare). In the dried bone this opening leads intothe vestibule of the internal portion of the ear. Below the fenestravestibuli is another opening (in the dried bone) that leads into thecochlea and is termed the. fenestra cochlecB.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthumananatomy, bookyea
