THE UTERUS. 1129 
the margin of the opening in the vaginal wall, through which it passes, and in this 
way a supravaginal portion (portio supravaginalis) is marked off from a vaginal 
portion (portio vaginalis) of the cervix. In the vaginal portion of the cervix there 
is an opening—the external os uteri (orificium externum uteri)—through which the 
cavity of the uterus communicates with that of the vagina. In the uterus which 
has never been pregnant this opening is nearly circular, but in women who have 
borne children it is usually a transverse slit with a somewhat irregular outline. In 
front of and behind this opening the cervix forms two lips, an anterior and a 
posterior (labium anterius et labium posterius). The anterior lip is thicker, more 
rounded, and placed upon a higher level than the posterior lip, which is longer and 
thinner. The cervix enters the vagina through the upper part of its anterior wall 
in such a manner that the external os uteri is directed against the upper part of 
the posterior vaginal wall (Fig. 775). . 
Parovarium Ligamen Lateral angle 
Fallopian tube | Ovary of ovary Uterus a of uterus 
Cavity 
of body 
Hydatid 
Cavity 
of cervix 
S= 
Round ligament Broad | = 
ligament = 
Vaginal cavity 
Fic. 774.—A. THE UTerus AND BrRoAD LIGAMENT SEEN FROM BEHIND (the broad ligament has been 
= spread out). 
a, 6, and c, the isthmus tube, the ligament of the ovary, and the round ligament of the right side eut short. 
B. DIAGRAMMATIC REPRESENTATION OF THE UTERINE CAVITY OPENED UP FROM IN FRONT. 
Cavity of the Uterus.—The cavity of the uterus (cavum uteri) is, owing to the 
great thickness of the uterine wall, small in comparison with the size of the organ. 
In the body the cavity is merely a narrow chink between the anterior and posterior 
walls, which are almost in contact (Fig. 775). When, however, the organ is opened 
from above downwards in coronal section the cavity of the body has a triangular 
outline (Fig. 774). The base of the triangle is directed upwards, and corresponds 
to a line drawn between the openings of the Fallopian tubes, while the apex is 
directed downwards towards the cervix. The sides of the triangle are convex 
inwards towards the cavity. The cavity of the body becomes continuous with that 
of the neck, or cervix, by an opening called the internal os uteri (orificlum internum 
uteri), which is a little smaller and more circular than the external os uteri. The 
cavity of the cervix, or cervical canal (canalis cervicis uteri), extends from the 
internal os uteri, where it joins the cavity of the body, to the external os uteri, 
where it opens into the vagina. It is a somewhat spindle-shaped passage which 
is narrower above and below than in its middle part; also sections show that 
its antero-posterior diameter is shorter than its transverse one, owing to an 
approximation of its anterior and posterior walls. In the body of the uterus the 
walls of the cavity are smooth and even, but in the cervical canal the mucous 
membrane forms a remarkable series of folds, called the arbor vite uterine or plice 
palmate. These consist of an anterior and a posterior longitudinally directed fold 
or ridge, from which a large number of secondary folds, or rugze, branch off obliquely 
upwards and outwards (Fig. 774). 
Connexions of the Uterus and its Relations to the Peritoneum.— In addition 
to the Fallopian tubes at its upper lateral angles, and the vagina below, the uterus 
possesses other important connections. Some of these are simply peritoneal folds 
passing from the uterus to neighbouring structures; others contain fibrous 
connective tissue, or smooth muscle fibres. 
