. Anatomy, descriptive and applied. Anatomy. 1130 THE ORGANS OF SPECIAL SENSE membrane, nearly oval in form, somewhat broader above than below, and directed A'ery obliquely downward and inward, so as to form an angle of about 55 degrees with the floor of the canal (Fig. 843). The antero-inferior portion is) therefore, placed at the greatest distance from the external orifice of the meatus. In a new- born child the membrana tympani is almost horizontal. The greatest diameter of the membrana tympani is from 9 to 10 mm.; its least diameter is from 8 to 9 mm. The greater part of its circumference
. Anatomy, descriptive and applied. Anatomy. 1130 THE ORGANS OF SPECIAL SENSE membrane, nearly oval in form, somewhat broader above than below, and directed A'ery obliquely downward and inward, so as to form an angle of about 55 degrees with the floor of the canal (Fig. 843). The antero-inferior portion is) therefore, placed at the greatest distance from the external orifice of the meatus. In a new- born child the membrana tympani is almost horizontal. The greatest diameter of the membrana tympani is from 9 to 10 mm.; its least diameter is from 8 to 9 mm. The greater part of its circumference (limbiis memhranae tymimnae) is thickened and fixed in a groove, the sulcus tympanicus, at the inner extremity of the external meatus. This sulcus is deficient superiorly at the incisure or notch of Rivinus (Fig. 846). From the extremities of the notch two folds, the anterior and posterior malleolar folds, are prolonged to the short process of the malleus (Fig. 846). The small, somewhat triangular part of the membrane situated RECESS PROMINENCE OF EXTERNAL SEMICIRCULAR CANAL E OF AQUEDUCT OF FALLOPIUS TENDON OF STAPEDIUS MUSCLE PLICA STAP / / X PROCESSUS COCHLCARIFORMI5 ^ TENSOR TYMPANI uscLE (cut through). Fig. 848.—The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral ^ (Spalteholz.) above these folds is lax and thin, and is named the membrana fiaccida of Shrapnell (Figs. 846 and 847); in it a small orifice is sometimes seen. The larger lower portion of the tympanic membrane is stretched tightly, and is called the tense portion or pars tensa (Figs. 846 and 847). The handle of the malleus is firmly attached to the inner aspect of the mem- brana tympani as far as its centre (Fig. 847), which it draws inward toward the tympanic cavity. The most depressed part of the concavity is called the umbo {itinbo memhranae tympanae) (Fig. 846). On the outer surface of the drum membrane a light stripe {stria malleolaris) is seen. It runs from i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
