186 



THE TYMPANIC MEMBRANE. [BOOK in. 



short process of the malleus abuts against this part of the mem- 

 brane (Fig. 168 p. &.), and when the membrane is viewed from the 

 outside, as in looking down the meatus, is seen shining through it 

 (Fig. 169 p. b.). 



mbr 



FIG. 169 THE MEMBRANA TYMPANI. (After Schwalbe.} (Magnified four times.) 



The membrane is seen from the external meatus and the handle of the malleus, 

 mbr, is represented as shining through, m.f. the membrana flaccida, the folds 

 of which are represented radiating from p. b., the projection outwards caused by 

 the end of the short process of the malleus, u the umbo of the membrane, to 

 which is attached the end of the handle of the malleus. The figure shews dia- 

 grammatically, the radial and circular fibres of the membrane. 



This larger tenser part of the membrane forms a shallow funnel, 

 the apex of which, called the umbo (Fig. 169, 170 u), projects into 

 the tympanic cavity ; and the handle of the malleus is attached 

 to this part of the membrane on its inner side in such a way that 

 the umbo is supported by the tip of the handle. The umbo is 

 somewhat eccentric in position, lying nearer the bottom than the 

 top ; and the sides of the funnel are not flat but slightly convex 

 towards the meatus, though not equally so in all parts. 



The membrane consists of a basis of connective tissue, mem- 

 brana propria, covered on the outside by a continuation of the 

 skin of the meatus, and on the inside by the mucous membrane 

 lining the tympanum. The connective tissue basis, which is 

 absent from the small flaccid part of the membrane, consists of 

 bundles of connective tissue, somewhat peculiar in appearance, 

 but yet ordinary fibrillated, inelastic gelatiniferous connective 

 tissue, arranged in an outer layer of radiating bundles, and a 

 thinner less complete inner layer of circularly disposed bundles ; 

 both layers, especially the circular, are thinner towards the centre 

 than at the circumference. The handle of the malleus is im- 

 bedded in, and wrapped round by the bundles of this connective 

 tissue, the radial bundles radiating from the umbo, or in the 

 upper part of the membrane diverging by the sides of the 

 handle. 



The skin covering the outer side of the membrane is ordinary 



