In nullipara3 this cavity is 2.1 inches according to Richet, 2.02 accord ing to Sappey. In parous women 2.3 inches according to Richet, 2.2 inches according to Sappey. This last author divides them thus: NulliparEe.—Cavity of the body 1.05 inches; cavity of the cervix 1.05 inches; intermediate canal .19 inches. MultiparEe.—Cavity of the body 1.05 inches; cavity of the cervix .69 inches; intermediate canal .19 inches. The cavity of the body is triangular, having two surfaces, two borders and three angles. The surfaces are planes placed one on the other. The borders, in nulliparae, are convex, the superior reaching the others by the tubes. The lateral run from the mouth of the tube to the internal ori fice. (See Fig. 34 and following.) The angles are: two superior, forming a funnel-shaped canal at the top of which the tube opens; an inferior, which extends to the isthmus, or intermediate part of the uterine cavity.
In multiparx the cavity of the body remains triangular, but the borders become rectilinear.
The walls are a little thicker at the fundus, where they are .39 of an inch; at the mouth of the tube they are but .31 inches. On the surfaces and lateral borders, on the contrary, the thickness is .46 inches.
The cavity of the cervix is shaped like a canal, distended in the middle, and flattened in front and behind, having two walls, two borders and two orifices.
The walls have a longitudinal projection, whence, running to the right and to the left, are secondary projections, ascending and oblique. This is the arbor vita. These two anterior and posterior projections are not similar. Their juncture is much more pronounced at the upper portion. The edge of the cavity describes a curve the concavity of which is not directly inward, but inward and slightly downward. (See Fig. 34 and following.) The internal orifice is from .19 to .23 inches in length. It forms a sort of strait by which the cavities of the body and neck intercommunicate. The markings of the arbor vitae are prolonged to its superior portion. After the menopause the internal os gradually contracts and can even dis appear entirely.
Relations of the Uterus.
The uterus is situated in the median line, between the rectum and the bladder, but slightly inclined to the right, its position corresponding to the curve of the pelvic canal. (Fig. 40). Its base is turned upward and forward when the woman is standing, the bladder very slightly dis tended, and when the intestines are not too greatly depressed. When, on the contrary, the bladder is distended, or the woman is lying down, the body of the uterus is pushed backwaid, and rests on the rectum. In these different positions the cervix varies but little, and is placed behind and below, in such a way that the os tincw rests on the posterior wall of the vagina, the anterior lip forward, the posterior lip backward.
The fund us never passes below the superior strait, often scarcely reach ing that.
The anterior surface is in contact, superiorly, with the peritoneum which covers it, with the intestine and the bladder, from which it is sepa rated by the vesico-uterine cul-de-sac. Inferiorly it is not covered by the peritoneum, and is closely connected with the bladder and vagina, the vaginal walls being inserted lower in front than behind.
In parous women the vaginal mucosa has always sagged somewhat; from this it follows that all that part of the anterior face of the uterus which is between the reflection of the vaginal mucosa on the cervix, and that of the peritoneum on this anterior surface, is closely connected with the posterior surface of the bladder. This space is about 1.1 inches long, and throughout its length, the union of the bladder with the superior wall of the vagina, and the corresponding part of the body and neck of the uterus, is made by cellular tissue, easily broken or torn off with the linger.
The posterior surface of the uterus is connected with the peritoneum, which covers its two superior thirds, below with the vaginal walls, which are a little higher than in front, and with the rectum. The uterine cul de-sac is there formed by the peritoneum. The edges are connected with the broad ligaments.
Structure of the Uterus.
The uterus consists of three coats: an external, serous or peritoneal, a middle or muscular tissue, an internal or mucous. • 1st. External or Peritoneal Coat.—In studying the relations of the uterus, we saw the position of the peritoneum on the anterior and pos terior surfaces. The peritoneum adheres much more strongly to the fun dus than to the cervix, and lateral borders; it is folded forward and back ward to form the vesico-uterine cul-de-sac in front, and the recto-uterine behind, and the two layers are placed back to back, as soon as they leave the border of the uterus to form the broad ligaments which will be de scribed later. (Fig. 33.) 2d. Muscular is formed of a muscular tissue so thick and compact that, when empty, it appears more like a fibrous tissue than a muscular one. It is only when pregnancy has excessively enlarged all its fibres that their position and arrangement can be observed. Their mus cular nature can then be proved. (See Article on Pregnancy.) 3rd. Internal Coat.—Although, in olden times, the existence of this coat was a subject of dispute, the researches of Coste and Robin have es tablished it beyond a doubt. It is a mucosa, having a different character in the body and in the cervix.