836 SPECIAL SENSES. 



ligament, the chorda tympani, and the anterior tympanic artery. The handle of the 

 malleus is inserted between the two layers of the fibrous structure of the membrana 

 tympani and occupies the upper half of its vertical diameter, extending from the periph- 

 ery to the umbo. 



The membrana tympani, though thin and translucent, presents three distinct layers. 

 Its outer layer is an excessively delicate prolongation of the integument lining the exter- 

 nal meatus, presenting, however, neither papillae nor glands. The inner layer is a deli- 

 cate continuation of the mucous membrane lining the tympanic cavity and is covered by 



FIG. 263. Eight membrana tympani, teen from within. Trom a photograph, and somewhat reduced. 



(Kudinper.) 



1, head of the malleus, divided ; 2, neck of the malleus; 3, handle of the malleus, with the tendon of the tensor tym- 

 pani muscle; 4, divided tendon of the tensor tympani; 5, (5. portion of the malleus between the layers of the 

 membrana tympani ; 7, outer (radiating) and inner (circular) fibres of the membrana tympani ; 8, fibrous ring of 

 the membrana tympani; 9, 14, 15, dentated fibres, discovered by Gruber ; 10, posterior pocket; 11, connection 

 of the posterior pocket with the malleus ; 12, anterior pocket ; 13, chorda tympani nerve. 



tessellated epithelial cells. The fibrous portion, or lamina propria, is formed of two 

 layers. The outer layer consists of fibres, radiating from the handle of the malleus to 

 the periphery. These are best seen near the centre. The inner layer is composed of 

 circular fibres, which are most abundant near the periphery and diminish in number 

 toward the centre. 



The color of the membrana tympani, when it is examined with an aural speculum by 

 daylight, is peculiar, and it is rather difficult to describe, as it varies in the normal ear in 

 different individuals. Politzer describes the membrane, examined in this way, as trans- 

 lucent, and of a color which " most nearly approaches a neutral gray, mingled with a 

 weaker tint of violet and light yellowish-brown. This color is modified, in certain por- 

 tions of the membrane, by the chorda tympani and the bones of the ear, which produce 

 some opacity. The entire membrane in health has a soft lustre. In addition, there is 



