1276 



UROGENITAL SYSTEM 



upper half of the vagina as a minute tube or fibrous cord. The external orifice 

 is surrounded by the fibres of the bulbo-cavernosus muscle, which may be re- 

 garded as forming a sphincter (sphincter vaginae). 



Structure. — The wall of the vagina is formed mainly of non-striped muscle tissue, whose 

 fibres are indistinctly arranged in two layers, an outer longitudinal and a less distinct inner 

 circular one. Above, this tissue is continuous with that of the cervLx uteri, as is also the mucous 

 membrane which lines the lumen. This differs from that of the cervix in having a stratified 

 squamous epithelium and in being destitute of glands. 



Vessels and nerves. — The arteries of the upper part of the vagina are derived from the 

 vaginal branch of the uterine; its middle portion is supplied by a vaginal branch from the 

 inferior vesical and its lower part by the middle hemorrhoidal and internal pudendal. The 

 veins form a rich plexus on the surface and drain into the hypogastric vein. The lymphatics 

 are very numerous and drain for the most part to the hypogastric and lateral sacral nodes; some 

 of those from the lower portion of the canal joining with those from the external genitalia to pass 

 to the inguinal nodes. The nerves passing to the vagina are derived from the utero-vaginal and 

 vesical plexuses. 



5. The Female External Genitalia and Urethra 



The female external genitalia [pudendum muliebre] (vulva) present an elon- 

 gated depression, occupying the entire perineal region and bounded laterally b}^ 



Fig. 1037. — The External Genitals of the Female. 



Mods pubis 





Glans cUtoridis with prseputium 

 and frenulum 



Urethral orifice 

 in vestibule 



Corpus clitoridis 



Labium majus 



Labium minus 



Hymen and orifice 

 of vagina 



- Fossa navicularis 



- Frenulum labiorum pudendi 



Anu&- 



Posterior commissure 



two folds of integument, the labia niajora (fig. 1037). These anteriorly are 

 continued into the mons pubis, an eminence of the integument over the symphysis 

 pubis due to a development of adipose tissue. The medial surfaces of the two 

 labia are normally in contact, the fissure between them being t(>rmed the rima 

 pudendi, and wli(;re they meet anteriorly and posteriorly they form the anterior 

 and posterior commissures [commissura labiorum anterior et posterior]. Just 

 anterior to the latter is an inconstant transverse fold, the frenulum labiorum 

 pudendi ("fourchette") (fig. 1037). The mons and the outer surfaces of the 

 labia are covered by short crisp hairs, but the medial surfaces of the labia are 

 smooth, possessing only rudimentary luiirs, but beset with large sebaceous and 

 sudoriparous glands. The interior of th(! labia is occupied by a mass of fat tissue 

 in which the distal extremity of the round ligament of the uterus breaks up. 



