Notes on Veterinary Anatomy

by Charles James Korinek

The Fallopian Tubes are two canals, one on each side. They pass backward and upward, and enter the front part of the uterus or womb. These small tubes are simply used to carry the germ or ovum up from the ovaries and empty into the uterus or womb.

The Uterus or Womb is a muscular sac situated in the pelvic cavity, bounded above by the rectum, below by the bladder, and on either side by the walls of the pelvic cavity. It is divided into what is known as a body and a neck. The body of the womb is very small, being only about four to six inches in length and a couple of inches in diameter when the animal is not pregnant. Near the front end, at the upper side there are openings by which the ovum enters. When the animal becomes pregnant, the body of the womb becomes enlarged and passes forward and to the left side of the abdominal cavity. It continues to enlarge as the time of pregnancy passes on, until the foetus, or young, has attained its full size. After the mare has had her young, the womb begins to get smaller until it attains its natural size again. The womb is very largely supplied with blood vessels and nerves. This is especially so when the animal is pregnant, as it takes a large amount of blood to nourish the foetus, or the young animal, before birth. It is made up of three coats. The inner is called mucous membrane, and in the mare, while pregnant, is covered with numerous processes about the size of peas to which the placenta or after-birth of the foal is attached. The muscular coat is next to that of the mucous coat, and lies between the outer and inner coats of the womb. It is made up of muscular fibres, and is strong and thick in the womb, much thicker than it is in the bowels or other organs, already mentioned. This coat supports and protects the foetus, or young, while being carried in the womb, and at the time of parturition, or what is commonly known as foaling, this coat also comes in use. It contracts the womb very forcibly on the foal, while the neck of the womb lies open, thus helping to force the foal out of the womb. This is important as the contraction of this coat produces what is known as labor pains. Lying outside, and covering around the womb, is a serous coat, a continuation of the serous coat of the bowels. The womb is held in place by strong ligaments attached to the sides, and from there to the hip bones. These are called broad ligaments. At the back part of the womb is the neck. It consists of an opening, formed by a projection about the size of an egg. This has a hard, gritty feeling when the animal is not in season. The neck at this time is closed. The neck of the womb is under control of the muscle around it, and this muscle is under control of the nerves of the womb. When a mare comes in season this muscle is relaxed to a certain extent, thus allowing the neck to open wide enough for the passage of a couple of fingers. By working around it with the fingers at this period it can be forced wide enough to admit a man’s hand. If the mare is put to the horse at this time and becomes pregnant or with foal, the muscles in the neck of the womb contract, firmly closing it. It remains closed until the time of foaling. When, at the time of foaling, the labor pains come on, the muscle in the neck dilates, allowing the neck of the womb to open large enough for the foal to pass out. The neck of the womb can be felt easily by oiling the hand and passing it into the passage of the womb. It will be noticed, too, that the neck spoken of projects into the passage.

The Vagina and the Vulva.—These two organs together make up the passage which leads into the womb from the outside. In the young mare they are separated by a thin curtain, or partition, made up of mucous membrane. This curtain is found about four inches from the outside, and is known as the hymen. It is destroyed, or should be, when the mare is first put to the horse, although it is broken down other ways, and in some cases it will disappear of its own accord. The part of the passage in front of the hymen is called the vagina. This passage, in structures, resembles the womb, but is not so strong. There are numerous glands situated along the inner lining which secretes a fluid to lubricate it. The principle use of this organ is to guide the penis during sexual intercourse, and at the time of foaling serves as a passage for the foal. That part of the passage behind the hymen is known as the vulva. It is about four inches long and about two or three inches high, varying according to the size of the mare. In front, it is separated from the vagina by the hymen membrane. It resembles the vagina in structure and is also provided with little glands in its inner membrane to secrete fluid to lubricate the passage. At the back part of the vulva or around the outside is what is known as the lips of the vulva, one on each side of the opening. The outside of the lips is covered by a very fine skin. Just below the skin, they consist of erectile tissue, which is the same kind of tissue as that of the penis of the horse. This tissue is found more abundantly in the lips of the vulva of the young mare than in those of an old mare. The opening between these lips is situated just below the anus, or the opening where the back bowel ends. At the back part of the vulva, on the under side, is an opening, or hole, about large enough for the passage of a man’s finger. Through this hole the tube leading from the bladder enters into the passage and allows the urine to pass into the vulva, through which it runs out of the body. The clitoris is situated on the upper side of this passage, just inside the lips. It can be seen in the mare when she works the vulva after passing urine. Just below the clitoris are found two or three small glands which secrete the fluid that passes away when the mare is horsing.

Mammary Glands, or what is known as the mare’s udder or bag, are two in number, situated between the thighs. In the young mare they are very small, but after the mare is pregnant a few months these glands enlarge, until at foaling time they attain their largest size. They are covered outside by a thin, smooth skin. The substance of them consists of small glands and tubes retain or hold milk until it is drawn away from the bag either by milking or by the young animals sucking. During the time of suckling the young, the glands are largely supplied with blood, from which the milk is secreted. On the under side of each gland is found the teat, or that part taken hold of by the young when sucking. The end of the teat is pierced by several small holes, through which the milk passes.

GENITAL ORGANS OF THE BULL.

The testicles are ovoid in shape and well developed, its long axis being nearly vertical; the membrane which separate the two testicles is very strong.

The spermatic cord and artery are small compared with those of the horse.

The penis is long and pointed, and has an S-shaped curve in it just below the pelvic bones; this curve can be felt by feeling just behind the bag.

The sheath is long and runs further forward on the belly. It has a tuft of hair on the point of it. During the time the bull is serving the S-shaped part of the penis is straightened out by the action of the protracter muscles, and drawn back into the S-shaped curve by retractor muscles.

The urethra is completely enveloped by the fibrous sheath.