Читать книгу Obstetrics for Nurses - Charles B. Reed - Страница 7

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Inside the pelvis are the organs of generation with their accessory structures and supporting tissues.

Of first importance are the ovaries, tubes and uterus, together with the vagina. These special structures are the true genital organs. They are bounded in front by the bladder, behind by the rectum, above by the abdominal viscera, and surrounded everywhere by muscular, mucous and fatty tissues, which support them and aid their function.

The Vagina.—The vagina is a hollow organ, about four inches long, attached to the cervix above and the vulva below. It is an elastic sheath bounded in front by the bladder and behind by the rectum. Under normal conditions, this tube easily admits one or two fingers, but during labor it dilates enormously to allow the head to pass. The vagina is lined with a thick mucous membrane, ridged and roughened by folds, which are called rugæ. Thus a continuous channel connects the ovary with the outside and through it pass, at appropriate times, the ovule, the menstrual blood, the uterine secretions, the child, the placenta, and the lochia.

The Uterus.—The uterus (womb) is a pear-shaped organ, flattened from before backward, and composed of unstriped or involuntary muscle cells and connective tissue. Normally the virgin uterus measures from two and one-half to three inches in length, and weighs about two ounces. It is suspended in the middle of the pelvis by strong ligaments, so that the fundus inclines gently forward against the bladder. When the bladder fills, the uterus is pushed backward. Most of the organ is internal, but a small part of the lower pole is grasped by the vagina, in which the lower end with its invaluable aperture, the os, dips and swings. The part above the vagina is called the body or fundus, and is covered with the serous membrane (peritoneum) that lines the abdominal cavity. Below the fundus is the cervix or neck, which lies partly above and partly within the vagina. The cavity of the uterus is usually closed by the apposition of the walls. The inner surface is covered with a peculiar kind of membrane called the endometrium, which is highly vascular. The uterine cavity opens into the vagina through the os, which is small and round in the nulliparous woman, and slit-shaped or gaping in the woman who has borne a child.

Fig. 4.—Uterus and appendages. On either side of the uterus will be seen the ovary, the fimbriated extremity of the tube, the tube, and the round ligament. The vagina lies open below. (Lenoir and Tarnier.)

Fallopian Tubes.—On either side of the upper end of the uterus are the orifices of the Fallopian tubes, through which the egg, escaping from the ovary, finds access to the uterine cavity. These tubes extend outward from the uterus about four inches, and terminate in a bell-shaped opening with long, ragged fingers which hang loosely down toward the ovary. The tubes are lined by epithelial cells having hair-like projections, (ciliæ) which wave automatically toward the uterus. Thus impelled by a gentle current, the egg moves definitely along the tube toward the uterus and against this current the spermatozoa force their way to meet and fertilize the egg.

The Ovaries.—On either side of the pelvis, close to the fringed end of the Fallopian tube and attached to it, lies a small, hard, almond-shaped organ, called the ovary. This is the intrinsic sexual gland of the female. It contains the small cells which are to ripen and become eggs. Each ovary is said to contain about thirty-six thousand eggs, or ovules.

The Bladder.—The bladder lies between the pubic bone and the uterus. It is a reservoir for urine, filled by means of two little tubes called ureters, that run down from the kidneys. It drains through the urethra which opens just below the pubic bone in front of, and just above, the vaginal opening. The bladder should be emptied frequently during labor.

The Anus.—The large bowel (colon) terminates in an opening near the middle of the genital crease. This opening is called the anus. It is closed by a contracting muscle, the sphincter, which acts like a puckering string. Just inside of the opening is a group of large veins which may become enlarged, inflamed, and bleed during pregnancy. They are then called hæmorrhoids.

The Rectum.—Upward from the anus and to the left of the uterus extends the rectum. This is the end of the intestinal canal and is supplied with an abundance of nerves. When the head presses upon it, it gives the sensation of a bowel movement, and warns the observer of the low position of the head. The anus pouts as the head comes down and the anterior walls become visible. In severe cases of labor, the sphincter is sometimes torn. The bowels should be emptied by an enema as early as possible in the first stage of labor.

The Peritoneum.—The peritoneum is a thin, glistening, serous membrane, which lines the abdominal cavity and drops down from above over the uprising tops of the bladder and uterus. Folding together at the sides and extending to the walls of the pelvis, it encloses the tubes and round ligaments in deep, flat masses, called the broad ligaments. This is the structure that becomes so perilously inflamed (peritonitis) when infected by germs that find entrance through the genital passage.

Fig. 5.—Normal position of pelvic organs, seen from above and in front. They are enveloped in peritoneum. (Bougery and Jacob, in American Text Book.)