THE Vagina is the membranous canal which leads from the vulva to the month of the uterus. When distended it is cylindrical in shape; and it is curved in its natural position, with the concavity looking towards the symphysis pubis. Extending from the vulva, or outlet of the inferior strait, to the superior strait, the direction of its curvature,-which exactly corresponds to the curve of the penis, is the same as that of the general axis of the pelvis. It is capable of dilatation for the introduction of the virile member, and still more for the passage of the foetal head in parturition; but, when not separated by such means, its anterior and posterior walls remain in apposition.
Anteriorly the vagina is in relation with the bladder and urethra, with which it is connected by a condensed cellular tissue. Posteriorly it is in relation with the rectum, to which it is attached by a considerable thickness of looser cellular membrane, – or party-wall common to both passages,-termed the recto-vaginal septum. This in displacements of the uterus, which necessarily affect the vagina. the rectum is seldom involved, while the bladder, being more firmly bound to the vagina, is always disturbed by such changes in the position of the uterus. Hence the incessant calls to pass water, with painful micturition or more or less complete retention of urine, so often seen in cases of anteversion, or prolapsus uteri.
Vertical Section of the Pelvis, showing the Organs in situ.
B. The bladder is seen in front, with its urethra passing out under the symphysis. Just behind it, the uterus U, and the vagina V, are observed to occupy the middle of the excavation; rectum R, is still more posterior, being separated from the vagina by the recto vaginal septum. P. The perineum.
By reference to the upper part of the figure, the peritoneum can be traced from the anterior abdominal walls to the fundus uteri, and then between the womb and rectum, forming another pouch, and finally to the posterior abdominal wall.
The length of the vagina differs in different persons, and different states of the same person. It is much longer posteriorly than anteriorly; and may be stated to be from four to five inches long on its anterior wall, and from five to six inches long on its posterior wall. It is very elastic, and is capable of being distended longitudinally as well as of being laterally dilated. In some instances it appears very much shorter than the natural standard. This shortening of the vagina may be accidental, merely the result of partial prolapsus of the uterus, or it may be congenital and permanent. In the former case, the womb may be pressed upwards and restored to its natural position, when the shortening of the vagina will at the same time disappear. But in the latter case, the uterus cannot be thus pushed up by the finger; and this circumstance conclusively determines the nature of the difficulty. Congenital shortening of the vagina may be an efficient cause of sterility; besides occasioning severe and constant inflammation of the cervix uteri, as the result of the frequent and unnatural contact in coition.
LIke the cavity of the pelvis, the vagina is narrowest at its external orifice, most capacious midway in its course, and again contracted at its superior extremity. Its circumference is about three inches.
The parietes of the vagina are formed of layers of areolar, fibrous, spongy and muscular tissue and mucous membrane, arranged in the following order. First we find the cellular or areolar tissue, already spoken of as connecting the vagina with the rectum, urethra and bladder; then between two very strong fibrous laminae we find a spongy, erectile tissue. Around the outer laminae are disturbed the muscular fibres, which are more numerous near the external orifice of the vagina, where they are arranged in concentric circles. In some females these muscular fibres are much more abundantly and powerfully developed than in others,-constituting a formation to which anatomists have given the name of sphincter vaginae; but so strongly marked a development of these muscular fibres as to warrant this team is not general. At the moment of the highest degree of excitement in coition, their contraction depresses the bulb of the vagina and the clitoris and grasps the virile member.
The internal coat of the vagina is composed of mucous membrane which is continuous with that which lines the inner surfaces of the external parts and with that of the cavity of the uterus. This mucous coat of the vagina is thrown into the numerous transverse or oblique folds, called rugae, which are more frequent at the lower part of the vagina. They are more apparent in virgins and in those who have never borne children, or who have passed the child-bearing period. These folds evidently constitute a provision for the dilatation of the vagina, to allow the passage of the child’s head; and they increase the voluptuous sensation in coition.
In the interstices of the rugae are found minute follicles, which especially during copulation, secrete a peculiarly stimulating fluid. In addition to these follicles the mucous surface of the vagina, especially at its lower portion with numerous muciparous glands, which pour out a profuse secretion, more abundant in coition and still more in parturition, which possess an acid reaction, the mucous secretion of the uterus being ascertained to be alkaline.
The vagina is abundantly supplied with blood-vessels, absorbents and nerves. The arteries are derived from hypogastric; the veins, which are numerous and plexiform, discharge into the hypogastric; the lymphatics discharge into the pelvic ganglia; and the nerves arise from the hypogastric plexus.
The superior extremity of the vagina enfolds the neck of the uterus, in a manner similar to the attachment of the Zouave pants to the legs,-forming an anterior and a posterior cul-de-sac; of which the latter is much the deeper. In cases of congenital shortening of the vagina, the posterior cul-de-sac is sometimes very much deepened by repeated extension in coition.
In its use, the vagina constitutes the female organ of copulation; affords an outlet for the escape of the menstrual secretion; and becomes the channel through which the child passes from the uterus, through the cavity of the pelvis, into the external world. After delivery it very speedily resumes its usual size; and in many instances its elasticity is so great that, even in such as have frequent and promiscuous sexual intercourse, it constantly maintains the size usually seen in virgins.