1044 THE FEMALE REPRODUCTIVE ORGANS 



gress, it may remain imbrokcii until i)arturiti()n. An imperforate condition of the 

 memljrane is occasionally present, and may necessitate a surgical operation at the 

 connnencement of the menstrual period. 



Structure. — The vaginal wall is composed of three coats, fil)rous, muscular, and 

 mucous, and has a thickness of one-eighth to one-sixth of an inch. The outer 

 fibrous coat is derived from the recto- vesical fascia, and holds in its meshes a plexus 

 of veins. The muscular coat comprises two layers of strong unstriped fibres, the 

 outer longitudinal, continuous above with the uterine muscle and with the utero- 

 sacral ligaments; and the inner circular and more largely developed near the vulvar 

 aperture. 



The mucous membrane is highly elastic, beset with papilla? and covered 

 with a scpiamous laminated epithelium continuous with that of the os uteri and 

 vulva. It has no glands, and hence the fluid which moistens it is rather of the 

 nature of a transudation than of a secretion. 



Vessels and Nerves. — The arteries are derived from an inferior branch of 

 the uterine and from the internal iliac, communicating below wdth branches of the 

 external pudic; they run along the lateral aspect of the passage and give twigs to 

 the anterior and posterior surfaces. The veins, similarly disposed, form a rich 

 network in the muscular and mucous coats, and terminate in the vaginal and 

 uterine trunks. The lymphatics, arranged in two intercommunicating networks, 

 mucous and muscular, from numerous trunks which accompany the veins and ter- 

 minate in the pelvic glands, a few from the neighbourhood of the vestibule, however, 

 reaching the inguinal glands. A small gland is occasionally found between the 

 rectum and vagina. 



The Nerves come from the hypogastric plexus, the fourth sacral, and the 

 pudic. 



THE UTERUS 



The uterus, or womb (figs. 635-638), is a hollow muscular organ lined with 

 mucous membrane. It communicates above with the two Fallopian tubes, and 

 below with the vagina, and lies within the pelvic cavity between the bladder and 

 rectum, fixed in its place by folds of peritoneum and certain bands of unstriped 

 muscle. It varies greatly in size and form at different periods of life and under 

 different physiological conditions. 



The adult uterus is flattened from before backwards, pyriform in its outlines 

 when seen from the front, and is divided into tw^o main portions, body and cervix, 

 by a transverse constriction, the isthmus. The isthmus may l3e regarded as the 

 weak point in the organ, and it is here that the various pathological flexions take 

 place. Its position in the virgin uterus is about midway between the two extremi- 

 ties, but it lies near the junction of the middle and lower thirds in women who 

 have borne children. 



The u))per ])ortion, or body, presents two surfaces, three borders, and two 

 angles. The anterior surface is almost flat, and is covered by a layer of peri- 

 toneum which is reflected at the level of the isthmus upon the bladder, forming a 

 shallow utero-vesical pouch which is occupied by coils of small intestine. The 

 posterior surface is distinctly convex, and covered in its whole extent by a layer 

 of peritoneum which is prolonged downwards over the neck and for a short distance 

 upon the posterior wall of the vagina before undergoing reflexion U})on the rectum 

 to form the recto-vaginal pouch, or pouch of Douglas. The superior border, 

 or base, is thick and rounded, and is covered by the })eritoneum, Avhich passes from 

 the anterior to the ])osterior surface. The lateral borders, slightl}' convex and 

 miming down-\vards and inwards, correspond to the line of attachment of the peri- 

 toneal folds called the broad ligaments. The superior angles, at the junction 

 of the superior with the lateral Ixn-ders, give attachment to the oviducts or Fallo- 

 pian tubes. The term fundus is loosely applied to the upper part of the body. 



The cervix is cylindric-al in section, wider in the middle than above or below, 

 and may be divided into three ])ortions, — an U])])('r supravaginal zone, a middle 

 zone of vaginal attachment, and a lower intravaginal zone, tlie os uteri. The 

 supravaginal zone, representing about one-half of the neck behind and two-thirds 



