An American text-book of physiology . continuous with the pharynx through the Eustachian tube. The inner wall slants somewhat outward from top to bottom, and it is formed chiefly by part of the bony envelope of the internal ear. The surface of this wall is pierced by two apertures, the fenestra ovalis, or oval window, and the fenestra rotunda, or round window, leading into the cavity of the bony labyrinth; in life each fenestra is covered by a thin sheet of membrane, and the foot of the stapes h fastened by a ligamentous fringe in the oval window. The outer wall of the middle ear is made up of
An American text-book of physiology . continuous with the pharynx through the Eustachian tube. The inner wall slants somewhat outward from top to bottom, and it is formed chiefly by part of the bony envelope of the internal ear. The surface of this wall is pierced by two apertures, the fenestra ovalis, or oval window, and the fenestra rotunda, or round window, leading into the cavity of the bony labyrinth; in life each fenestra is covered by a thin sheet of membrane, and the foot of the stapes h fastened by a ligamentous fringe in the oval window. The outer wall of the middle ear is made up of the tymj>anic Fig. 267.—Tympanum of left ear, with ossicles m situ(after Morris): 1, suspensory ligament of malleus ; 2, headof malleus ; 3, epitympanic region; 4, external ligamentof malleus ; 5, processus longus of incus; 6, base of stapes;7, processus brevis of malleus; 8, head of stapes; 9, o>!orbicnlare; 10, manubrium ; 11, Eustachian tube ; 12, exter-nal auditory meatus: 13, membrana tympani; 14, lowerpart of Fig. 268.—()tosco|iic view of left membranatympani (Morris): 1, viembrana flaccida; 2,2,folds bounding the former; 3, reflection fromprocessus brevis of malleus; 4, processus lon-gus of incus (occasionally seen): .>, mem-brana tympani; 6, umbo and end of manu-brium ; 7, pyramid of light. THE SENSE OF HEARING. 809 membrane and tlie ring of bone into which tliis membrane is roof is formed by a thin plate of bone, the tegrnen, which separates itfrom the cranial cavity, and the narrow floor, concave upward, is just abovethe jugular fossa. The cavity is lined by mucous membrane continuous withthat of the Eustachian tube and the pharynx, and the membrane, like thatof the Eustachian tube, is ciliated except over the surfaces of the ossicles ahdthe tympanic membrane. Suppurative inflammation of the middle ear maynot only involve the mastoid cells, but may also cause absorption of the tiiinplate of bone forming the roof of the tympanic ca
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Keywords: ., bookautho, bookcentury1800, bookdecade1890, booksubjectphysiology
