THE EXTERNAL EAR. 29 



EXTERNAL AUDITORY MEATUS. The external auditory meatus 

 presents a cartilaginous and a bony division, which together have 

 an average length of twenty-four millimeters (Troeltsch, 45), of 

 which eight millimeters belong to the first, and sixteen to the 

 latter. The width of the meatus is subject to individual varia- 

 tions. The cartilaginous portion extends from the auricular 

 cartilage and the tragus, and forms a channel or groove open be- 

 hind and above, which is completed into a tube by fibrous tissue. 

 It is moveably connected with the osseous portion of the meatus 

 by a slender band of connective tissue. The cartilage itself pre- 

 senting the same characters as that of the auricle, has, with a 

 view to its greater moveability, up wards and backwards, towards 

 the anterior and inferior wall, two fissures, the spaces of which 

 are occupied by connective tissue. The cutis of the external 

 auditory meatus is a continuation of that of the auricle and of 

 the tragus. It is not everywhere alike, but exhibits differences 

 in different parts, both in regard to its thickness and its internal 

 structure. In the cartilaginous portion of the meatus the cutis 

 is one millimeter and a half thick, is covered with woolly hairs, 

 with which sebaceous and ceruminous glands are connected, and 

 contains but little fat in the subcutaneous connective tissue ; in 

 the osseous portion the cutis rapidly alters, its thickness dimi- 

 nishing to 0*1 of a millimeter, the woolly hairs becoming finer and 

 fewer in number, and the ceruminous glands, except upon the 

 posterior and superior wall, are continued (though not in all 

 instances) as far as the transition into the tympanic membrane. 

 Beneath the epidermis are low papillae arranged in longitudinal 

 rows, and a corium containing much elastic tissue, the deeper 

 layers of which represent the periosteum. The ceruminous 

 glands agree both in the time and mode of their development, as 

 well as in their external form and in their minute anatomy, with 

 the sudoriparous glands. The same may be said of the contents 

 of the ceruminous glands, so far as we may judge from a micro- 

 scopical examination, except that the cerumen often contains 

 confusedly aggregated pigment granules. (See this Manual, 

 vol. ii., p. 597.) The ceruminous and sebaceous glands to- 

 gether furnish a whitish yellow, more or less fluid, secretion, 

 that essentially consists of various-sized fat molecules, and a 

 conglomerate of colouring particles and cells, in which last a 



