THE ORGAN OF HEARING. 



379 



cutaneous layer, the other group coming from the vessels of the 

 tympanic cavity to break up into the net-works distributed to the 

 mucous layer. 



The lymphatics of the tympanum correspond in their arrange- 

 ment with the principal strata of the membrane. In the corium of 

 the skin-layer lies a close net-work of capillary lymphatics ; these 

 increase in size towards the periphery, where they are collected into 

 larger trunks, which in turn empty into the lymphatic channels of the 



FIG. 394. 



Section through human malleus and tympanic membrane : i, bony tissue of manubrium, containing 

 medullary canal (2) ; 3, hyaline cartilage of malleus ; 4, 5, lamina propria of tympanic membrane 

 attached to malleus ; 6, cutaneous layer ; 7, mucous membrane covering hammer ; 8, blood-vessel ; 

 9, fragment of fibro-cartilage. (After Riidinger.) 



external auditory canal. Within the mucous stratum a much less 

 important lymphatic net-work exists, which communicates at the 

 periphery with the lymphatics of the mucosa of the tympanic cavity. 

 Suitable silver staining shows the existence of lymph-spaces in 

 certain places, in both the fibrous layer and the mucous membrane. 



The nerves of the membrana tympani follow the blood-vessels in 

 their distribution so far that they also comprise two sets destined 

 for the cutaneous and mucous layers. The nerves of the cutaneous 

 stratum, chiefly derived from the tympanic branch of the auriculo- 

 temporal, pass behind the manubrium of the malleus to divide at the 



