THE LABIA, termed alsci labia niajora, to distinguish them from the lesser labia or nymplue, are two symmetrical tegumental folds(fig. 480. /0, placed one on either side of the rima or fissure which leads to the vagina. The labia vary considerably in size and form in different subjects. In stout adults they are full and fleshy, closing the vulvar orifice, and con cealing the rest of the generative organs, which they serve to protect. In the aged the labia become shrivelled and the nymph pro trude between them, as they also commonly do in infants and young subjects. The outer surface of each labium is composed of com mon integument, which at the age of puberty becomes covered with hair. Along the line of apposition of the two labia, where the rima is formed, the hair and integument cease, and the ntucous membrane common to the rest of the generative canal commences. From this point inwards the iurface of the labium is smooth, of a reddish or pink colonr, and is here furnished with numerous muciparous and sebaceous follicles, which bedew the parts with an odorous secretion, and preserve their constant ntoisture. The labia are united above by a slight frenulum, termed the ante rior commissure, while below they are con nected, at the anterior tnargin of the perineum, by- a broader posterior commissure. When the
parts are here drawn asunder, a second fold appears within the former, just below the entrance of the vagina. The transverse boat shaped furrow between these constitutes the fossa navicularis. Beneath the cutaneous and mucous covering of the labia is found a layer of dartoid tissue, the rest of their substance being formed of loosefibrous and adipose tissue.
The labia represent the scrotum, which in the early fcetus is divided into two halves. A raphe indicates in the male the line of their subsequent confluence. In the female the two halves remain permanently separate. The normal descent of the testis into the scrotum in the male, about the seventh month of intra-uterine life, is represented by the ab normal descent of the ovary into the labia of the female which constitutes ovarian ingui nal hernia. (See p. 574.) When the labia are drawn asunder, the clitoris, the vestibule, nymphm, and vaginal orifice are brought into view.