1384 



HUMAN ANATOMY. 



which constitutes a considerable part of the corium, occurs as fibres and net-works, 

 which within the reticular stratum form robust tracts corresponding in their 

 disposition with the general arrangement of the fibrous bundles. Towards the 

 surface of the corium, the elastic fibres become finer and more branched and beneath 

 the epidermis anastomose to form the delicate but close subepithelial elastic net-work 

 that is present over the entire surface of the body with the exception, possibly, of 

 the eyelids (Behrens). 



The tela subcutanea, the deeper layer of the connective tissue portion of the 

 skin, varies in its thickness, and in the density and arrangement of its component 

 bundles of fibro-elastic tissue, with the amount of fat and the number of hair-follicles 

 and glands lodged within its meshes. 



The latter are irregularly round and enclosed by tracts of fibrous tissue, some 

 of which, known as the retiiiacida cutis, are prolonged from the corium to the deepest 

 parts of the subcutaneous stratum. Here they often blend into a thin but definite 

 sheet, \\\^ fascia subcutanea, which forms the innermost boundary of the skin and is 



Fig. I 148. 



Epidermis 



— Papillary stratum 



Reticular stratum 

 Hair follicle 



Retinaculum 



Fat 



Section of skin, showing its chief layers — epidermis, corium and tela subcutanea. X 17. 



connected with the subjacent structures by strands of areolar tissue. Where such 

 loose connection is wanting, as on the scalp, face, abdomen (linea alba), palms and 

 soles, the skin is intimately bound to the underlying muscles or fasciae and lacks the 

 independent mobility that it elsewhere enjoys. The integument covering the eye- 

 lids and penis is peculiar in retaining to a conspicuous degree its mobility although 

 devoid of fat. Where the latter is present in large quantity, the term pannicuhis 

 adiposus is often applied to the tela subcutanea. 



In places in which the skin glides over unyielding structures, the interfascicular 

 lymph-spaces of the tela subcutanea may undergo enlargement and fusion, resulting 

 in the production of the subcutaneous mucous bursae. These are found in many 

 localities, among the most constant. bursae being those over the olecranon, the patella 

 and the metatarso-phalangeal joints of the little and the great toe. The bursae in 

 the latter situation, when abnormally enlarged, are familiar as bunions. 



In addition to the strands of invohmtary muscle associated with the hairs as the 

 arrectores pilorum, unstriped muscular tissue is incorporated with the skin in the 

 mammary areolae and over the scrotum and penis (tunica dartos). The facial 

 muscles having largely cutaneous insertions, the skin covering the face is invaded 

 by tracts of striated muscular tissue that penetrate as far as the corium. 



