14 io THE URINOGENITAL ORGANS 



They contain fibrous tissue and unstriated muscle fibre. Muscle fibres from the 

 uterine wall to the rectal wall constitute the Rectouterinus muscle (musculus recto- 

 uterinus). This muscle is part of the sacrouterine ligaments. 



A round ligament (ligamentum teres uteri} (Figs. 1161 and 1166) is attached on 

 each side of the uterus. The two ligaments are rounded cords between four and 

 five inches in length, each situated between the layers of the broad ligament 

 in front of and below the Fallopian tube. Commencing at the superior angle 



the uterus, this ligament passes forward, upward, and outward through the 

 internal abdominal ring, along the inguinal canal, to the labium majus, in which 

 it becomes lost. The round ligament consists principally of muscle tissue pro- 

 longed from the uterus; also of some fibrous and areolar tissue, besides bloodvessels 

 and nerves, enclosed in a duplicature of peritoneum, which in the fetus is pro- 

 longed in the form of a tubular process for a short distance into the inguinal 

 canal. This process is called the canal of Nuck. It is generally obliterated in 

 the adult, but sometimes remains pervious even in advanced life. It is analogous 

 to the peritoneal pouch which precedes the descent of the testis. 



The cavity of the Uterus (cavum uteri) (Fig. 1164) is small in comparison with 

 the size of the organ, because of the great thickness of the wall. That portion 

 of the cavity which corresponds to the body is triangular, flattened from before 

 backward, so that its anterior and posterior walls are closely approximated, 

 and having its base directed upward toward the fundus. At each superior 

 angle is the minute orifice of the Fallopian tube. At the inferior angle of the 

 uterine cavity is a small constricted opening, smaller and more nearly circular 

 than the external os uteri, the internal os uteri (orificium inter num uteri} (Fig. 

 1164), which leads into the cavity of the cervix. 



The cavity of the cervix (canalis cervicis uteri) (Fig. 1164) extends from the 

 internal os uteri to the external os uteri. It is somewhat fusiform, flattened from 

 before backward, broader at the middle than at either extremity, and communicates 

 below with the vagina. The wall of the canal presents, anteriorly and posteriorly, 

 a longitudinal column, from which proceed a number of small oblique columns, 

 giving the appearance of branches from the stem of a tree; and hence the name 

 uterine arbor vitae (plicae palmatae) applied to it. The longitudinal ridges are not 

 exactly apposed, but fit against each other so as to close the cervical canal. These 

 folds usually become very indistinct after the first labor. 



The total length of the uterine cavity from the external os to the fundus is about 

 two and a half inches. 



The Uterus at Different Ages. The uterus of the fetus is in the abdominal cavity pro- 

 jecting above the brim of the pelvis. The cervix is considerably larger than the body. At 

 birth the cervix is larger relatively than in the adult; there is no distinct internal os distinguishing 

 the cavity of the body of the uterus from the cavity of the cervix. The arbor vitse is distinct and 

 extends to the upper part of the cavity of the organ. The growth of the uterus is slow until 

 puberty is almost reached, when for a time the growth is rapid. The growth of the uterine body 

 causes the mucous membrane of this part to lose its folds, hence the arbor vitae disappears from 

 the body. In a woman who has had children the uterine cavity is larger than in a woman who 

 has never borne a child. In advanced years the uterine wall becomes paler and hard and rigid 

 from atrophic fibrous changes. A more distinct constriction separates the body and cervix. 

 The internal os frequently and the external os occasionally are obliterated in old age. 



Abnormalities. Very rarely the uterine cavity is divided into two by a septum. Occasionally 

 the condition known as bicornate uterus exists. In this condition each lateral angle is pro- 

 longed into a horn or cornu. The uterus is formed by the union of the two ducts of Miiller, and 

 failure of fusion of these ducts makes a double uterus or a bicornate uterus. 



Changes at a Menstrual Period. For several days before the menstrual flow begins the 

 mucous membrane increases in thickness and vascularity and its surface is cast into folds. After 

 these preparatory changes the superficial portions of the mucous membrane break down and are 

 cast off, and bleeding begins. At the termination of menstruation the mucous membrane 

 rapidly regenerates. At each menstrual period from four to five fluidounces of blood are dis- 

 charged. The meaning of menstruation is uncertain. Pfliiger believes the wall of the uterus 



