420 



DISSECTION OF THE PELVIS. 



has columns 

 and rugae. 



Thickness. 



Three coats : 



mucous, 

 muscular, 

 and fibrous ; 



also erectile 

 tissue. 



Mucous 

 membrane. 



Arteries. 



Veins are 

 plexiform. 



Nerves. 



Lymphatics 



os uteri. On the inner surface, towards the lower part, is a longi- 

 tudinal ridge both in front and behind, named columns of the vagina. 

 Before the tissue of the vagina has been distended, other transverse 

 ridges or rugae pass between the columns. The wall of the vagina 

 is thicker in front round the urethra than at any other part of the 

 canal. 



Structure. The vaginal wall has a muscular coat, composed of un- 

 striped fibres both longitudinal and circular, which is thin above, 

 and increases in thickness below. It is lined internally by mucous 

 membrane, and covered externally by a layer of connective tissue 

 containing a dense network of veins. The prominence of the 

 columns is mainly due to a collection of vascular cavernous tissue 

 between the mucous and muscular layers. 



The mucous membrane is continued through the lower aperture to 

 join the integument on the labia majora, and through the os uteri, 

 at the opposite end, to the interior of the uterus. Many mucous 

 glands open on the surface, especially at the upper part. 



Blood-vessels and nerves. The arteries are derived from the vaginal 

 and uterine branches of the internal iliac. The veins form a plexus 

 around the vagina, as well as in the genital organs, and open into 

 the internal iliac vein. The nerves are derived from the pelvic 

 plexuses, as described on page 404. 



The lymphatics accompany the blood-vessels to the glands by the 

 side of the internal iliac artery. 



Uterus : 



form; 



dimensions ; 



upper end ; 



the lower 

 end is 

 small, and 

 has an 

 opening ; 



neck; 



THE UTERUS. 



The uterus or womb is formed chiefly of unstriated muscular 

 fibres. Its office is to receive the ovum, and to contain the 

 developing fetus. 



This viscus in the virgin state is somewhat pear-shaped, the body 

 being flattened (fig. 146 and fig. 156, p. 422), and the narrow end 

 below. 



Before impregnation the uterus measures about three inches in 

 length, two in breadth at the upper part, and an inch in greatest 

 thickness. Its weight varies from an ounce to an ounce and a half. 

 But after gestation its size and volume always exceed the measure- 

 ments here given. 



The upper end is convex, and is covered by peritoneum : the 

 name fundus is given to the part of the organ above the attachment 

 of the Fallopian tubes. 



The lower end is small and rounded, and in it is a transverse 

 aperture of communication between the uterus and the vagina, 

 named os uteri externum: its margins or lips (labia) are smooth, 

 and anterior and posterior in situation, but the hinder one is the 

 longer and thinner. Towards the lower part the uterus is con- 

 stricted ; and the smaller portion is called the neck (cervix uteri ; b) ; it 

 is nearly an inch in length, and gradually tapers to wards the extremity, 

 where it projects into the vagina, being enclosed by this tube to a 

 greater extent behind than in front. 



