THE VAS DEFERENS. 1109 
the prostate the vas deferens becomes once more a narrow canal, and 1s joined by 
the duct of the corresponding seminal vesicle to form the common ejaculatory 
duct, which, after a short course downwards and forwards through the prostate, 
opens into the urethra. ’ 
In some cases the vas deferens crosses the obliterated hypogastric artery before it enters the 
pelvic cavity ; it normally does so in the foetus. 
Common Ejaculatory Duct (ductus ejaculatorius).—This duct, formed by the 
union of the vas deferens with the duct of the corresponding seminal vesicle, is less 
than one inch in length, and lies very close to its fellow of the opposite side as it passes 
Posterior superior 
iliac spine 
Posterior superior 
iliac spine 
Ureter Cut end of rectum 
te h \ : ; a ——-—-— Apex of sacrum 
Great sciatic noteh—W— ‘ * : Lyf Wy, ae = Great sciatic notch 
Vas deferens- + —___--—-— Ureter 
_ Spine of ischium- —— ———— Perinoneulml 
Vas deferens = Ro é if - - - —__——.—Spine of ischium 
________ Bladder wall 
Seminal vesicle — 
mee Seminal vesicle 
Ampulla of vas deferens 
( Cut end of great sacro- 
~( sciatic ligament 
—Common ejaculatory duct 
Levator ani 
6 Prostate 
Ischio-rectal fossa 
Tuberosity of \ 
ischiium f-~ — 
Levator ani 
Tuberosity of ischium 
Ischio-rectal fossa 
Cut end of rectum 
= ——External sphincter ani 
Gluteus 
maximus Gluteus maximus 
Fic. 755.—VIEW OF THE BASE OF THE BLADDBR, PROSTATE, SEMINAL VESICLES, AND VASA 
DEFERENTIA FROM BEHIND. 
The coccyx and sacro-sciatic ligaments, together with the muscles attached to them, have been removed. The 
levatores ani have been separated along the median raphe, and drawn outwards. A considerable 
portion of the rectum and the upper part of the right seminal vesicle have been taken away. The recto- 
vesical pouch of peritoneum is coloured blue. 
through the prostate behind its mesial lobe. The ducts open by slit-like apertures into 
the first part of the urethra on each side of the sinus pocularis (utriculus prostaticus). 
Seminal Vesicles.—The vesiculae seminales, or seminal vesicles, are a pair 
of hollow sacculated structures placed in front of the rectum and behind the 
bladder (Fig. 755). Each vesicula seminalis is usually about two inches in length, 
and has its long axis directed downwards, inwards, and somewhat forwards. 
The upper extremity of the vesicle, which is partly covered by peritoneum, is large 
and rounded, and lies at a considerable distance from the middle line, behind the 
lower end of the ureter. The vesicle tapers towards its lower end, which is placed 
