THE SKIN. 287 



Muscles. Striated and non-striated muscles are present in 

 the skin. The former are found both in the smooth and in the 

 bearded parts of the face, and also in the nose. They arise from 

 the deeply seated muscles, and passing vertically, or more or 

 less obliquely, upward between the hair-follicles and the glands 

 of the skin, terminate in the corium. 



The non-striated muscles are very numerous, and run either 

 in a parallel or in an oblique direction to the general surface 

 of the skin. Those lying parallel with the general surface run 

 either in a straight or circular direction. When they run in a 

 straight direction and anastomose with each other they form 

 a network, as in the scrotum, prepuce, and perineum. The 

 straight running muscles are found, especially in the scalp and 

 in the axilla, both above and below the sweat-glands. Where 

 the muscles have a circular course, as in the areola of the nip- 

 ple, a continuous ring muscle is formed. 



The majority of the muscles running in an oblique direc- 

 tion have a special relation to the hair-follicles. The muscle 

 arises from the internal sheath of the hair-follicle and passing 

 obliquely upward, skirting the lower surface of the sebaceous 

 gland, terminates in the upper part of the corium (Fig. 122, ri). 

 Occasionally two muscles, situated on opposite sides, arise 

 from a single hair-follicle sheath. A muscle in its course up- 

 ward frequently divides into two or more bundles, these sec- 

 ondary bundles afterward pursuing different directions from 

 each other, and sometimes uniting with fibres from other mus- 

 cles, form a network in the corium. Sometimes an entire 

 muscle, or a secondary bundle, passes upward into a papilla 

 of the cutis and is inserted into the dense fibrous connective tis- 

 sue directly beneath the rete Malpighii. Occasionally several 

 secondary bundles run nearly parallel with each other and ter- 

 minate either separately in the corium, or conjointly, after 

 uniting. 



The skin is provided with other muscles which have no spe- 

 cial relation to the hair- follicles, but pass more or less verti- 

 cally upward from the subcutaneous tissue to be inserted in 

 the corium. 



The number of muscles present in the skin varies in differ- 

 ent regions of the body. They are most numerous in the scro- 

 tum. The order of frequency in the different parts of the body 

 is as follows : Scrotum, penis, anterior part of perinseum, scalp, 



