Fig. 15.
This profile view gives an exact idea of the dimensions of the cavity of the body and of the neck of the womb in a state of vacuity. A Mucous membrane. B. Tissue proper C. Cavity of the body. D. Cavity of the neck.
(Fig. 14 B.) is triangular in shape; its inferior angle corresponding to the os internum,- the two superior and lateral angles being situated at the orifices of the Fallopian tubes. IN Fig. 15 appears a profile view, which conveys a more correct idea of the manner in which the walls of the virgin uterus are approximated in their ordinary condition. At the times of the menstrual excitement, they are somewhat more distended.
The external dimensions of the uterus vary in different persons- being larger or smaller, to correspond with the totality of their physical constitution. We give what may be considered the average ad measurements of the fully developed uterus at puberty. The entire length of the uterus, from the inferior margin of the cervix to the superior border of the fundus, is about two inches and a half; its greatest breadth is about one inch and a half; and its thickness from the anterior to the posterior face is one inch. As the uterus increases in size from childhood to puberty, -so from the cessation of the menses it begins to diminish the volume, till it becomes more or less atrophied in the second childhood of advanced age. And as in the impregnated condition, the womb becomes very greatly and permanently enlarged, that is, during the continuance of the pregnancy, so at the accession of each of the monthly periods, in many females, it becomes temporarily enlarged to twice its natural size. The weight of the virgin uterus may be set down as about eight drachms; but after child-bearing it remains two or three times as heavy.
The structure of the uterus forms a very important element in studying its nature and functions. Three distinct tissues, coats or tunics,- each possessing a different constitution, and performing totally different functions,- make up this complicated structure. These are the external or peritoneal coat; the middle or muscular coat; and the internal or mucous coat.
The external or peritoneal coat.- This membrane is reflected from the posterior surface of the bladder upon the anterior face of the uterus; extends upwards, and covering the fundus, is continued down upon the vagina a short distance below the cervix; and is then finally reflected upon the rectum. The peritoneal membrane, or serous tissue, is thus seen to be identical and continuous with the common lining membrane of the abdomen. Processes from this membrane are reflected from each lateral border of the fundus to the corresponding side of the pelvis, near to the sacro-iliac symphysis. These processes form what are called the broad ligaments of the uterus; and contain the Fallopian tubes, the ovaries and the round ligaments.
The middle or muscular coat forms the principal part of the substance of the uterus. This tissue is dense, firm, and grayish in color. It is thickest upon the middle of the body and fundus; thinnest at the orifices of the Fallopian tubes. It consists of bundles of involuntary muscular fibres disposed in three layers intermingled with areolar tissue, blood-vessels, lymphatics and nerves. The external layer principally upon the anterior and posterior surface; its fibres, converging at each superior angle of the uterus, are continued upon the Fallopian tubes, the round ligament and ligament of the ovary,-some few running backwards from the cervix uteri to connect with the recto-uterine ligaments. The middle layer of this coat is composed of longitudinal, oblique and transverse muscular fibres. The internal layer consists of circular fibres arranged in the form of hollow cones, whose apices surround the orifices of the Fallopian tubes, their bases meeting and intermingling at the middle of the body of the uterus. The fibres of this layer are disposed transversely, or circularly, in the cervix uteri. The womb is a muscular organ of very great power; and a thorough knowledge of the nature and arrangement of its muscular fibres in the cervix, and especially in the fundus, and in their relation to the broad and other ligaments, is essential to a correct understanding of its wonderful action in parturition.
Fig. 16.
This figure represents the arrangement of the mucous membrane, and the tissue proper of the uterus, as also their relative dimensions. A Cavity of the neck and arbor vitae. B. Cavity of the body. C. Mucous membrane. D. Intervening membrane. E. Represents the marked thinning off the mucous membrane towards the neck.
The mucous coat of the uterus is so closely adherent to the subjacent tissue, that from the difficulty of separating and demonstrating its existence has been denied by many authors. But by the aid of the microscope this mucous coat has not only been clearly distinguished, but shown also to consist of epithelium, basement membrane, fibrous tissue, blood -vessels and nerves, like other mucous membranes. This internal mucous coat of the uterus is continuous with that of the vagina beneath, and also with the peritoneum above through the fimbriated extremity of the Fallopian tubes. It abounds in follicles, whose secretion lubricates the interior surface of the uterus. And the abnormal, catarrhal and leucorrhoeal secretions and other morbid products, to be subsequently considered as disorders of the cervix and even of the fundus, conclusively show the mucous character of this innermost tissue of the uterus. Numerous follicles, glands and papillae appear in the mucous lining membrane of the cervix; the secretions from which serve to maintain the mouth of the virgin uterus in a healthy condition, and to seal it when impregnated. Much the larger portion of the mucous secretion from the womb, is in reality the product of the innumerable glands of the cervix. This secretion in its normal state is whitish, very viscid, almost transparent, and gives an alkaline reaction. It adheres to the crypt and rugae of the cervix and occupies its canal.
The circulatory system of the uterus forms a most important part of its study. The blood vessels of the virgin womb are numerous and largely developed in comparison with the size of the organ. This has reference not only to the nutrition of the womb in its ordinary condition, and to its congested state at the periods of menstrual excitement, but is provisional also for the necessities of that impregnated condition for which its designed. The arteries, which supply the womb, form two distinct systems, according to the sources from which they are derived, and to the parts to which they are finally distributed. The first or superior system, is composed of the spermatics, or ovarian arteries, which arise from the aorta or emulgent arteries, and, descending along the sides of the womb in a serpentine course, are distributed to its upper part, to the Fallopian tubes, and to the ovaries. The second, or inferior system, is composed of the uterine arteries,- which are derived from the internal iliac or hypogastric arteries. These arteries also pass along the sides of the womb, to be finally distributed to the cervix and upper part of the vagina. These arteries pursue a remarkably tortuous course in the substance of the uterus; thus provision is made for their great elongation without danger of rupture in the advanced stages of pregnancy. The numerous branches of these two systems freely anastomose with each other.
The veins of the virgin uterus are of large size, possess no valves, correspond in name with the arteries, and follow their course. The right spermatic vein terminates in the inferior vena cava, the left in the renal vein; the uterine veins empty into the internal iliacs. They are capable of very great increase in pregnancy and are then known as uterine sinuses.
The lymphatic vessels of the uterus, invested by delicate coverings of peritoneum, are distributed upon all the external surfaces of that organ. They are very numerous and, in the virgin uterus, very small. Some of these ascend, in a serpentine course, from the cervix to the body and fundus of the uterus. Others pass less tortuously, in various directions over both these surfaces, communicating with branches ascending from the vagina and with those from the Fallopian tubes and ovaries. The internal as well as the external surfaces of the uterus, Fallopian tubes and ovaries, are abundantly supplied with these absorbent vessels. Those of the former, from the interior structure of these organs, communicate with the lumbar ganglia; those of the latter, from the external surfaces of the uterus, Fallopian tubes and ovaries, are abundantly supplied with these absorbent vessels. Those of the former, from the interior structure of these organs, communicate with the lumbar ganglia; those of the latter, from the external surfaces of these genital organs, communicate with the pelvic or inguinal ganglia. This latter circumstances is important to be borne in mind, since this anatomical and physiological connection is frequently the index to pathological appearances. In addition to the general division of the lymphatics of these organs, to correspond to their external and their internal surfaces,-the mode in which they are originally disturbed, to follow the course of the spermatic and iliac arteries, arrange them all in two distinct systems of lymphatic circulation. With the exception of the proper menstrual secretion, there is no discharge from the interior of the female organs of generation, in their normal condition; the lymphatics sufficing to reabsorb the natural secretions of their internal surfaces, so that no accumulation occurs.
