THE VAS DEFERENS
The vas deferens is a tube about 45 cm (1.5 ft) long. It begins at the inferior, posterior aspect of the testis and ascends superiorly and enters the inguinal canal. The vas deferens, together with the blood vessels, lymphatic vessels, nerves, muscles, and connective tissue fascia that surrounds it in this region, is known as the spermatic cord (Figure 7.2). The spermatic cord consists of structures that accompany the testis as it descends from the abdomen early in life. It ex-tends from the deep and inferior aspect of the ante-rior abdominal wall—the deep inguinal ring—to the testis. The structures, after entering the deep inguinal ring, pass through the inguinal canal, exit through the superficial inguinal ring (superficial aspect of the anterior abdominal wall), and descend superfi-cially to reach the testis (the route taken by the testis as it descends). In males, as a result of the presence of the spermatic cord, this region of the anterior ab-dominal wall is weaker. In situations where the pres-sure in the abdominal cavity is chronically increased, the contents of the abdomen tend to push through this weak point, a condition known as inguinal her-nia. In females, only a nerve and a ligament of theuterus pass through this canal and inguinal hernia rarely occurs.
After passing through the deep inguinal ring, the vas deferens passes posterior to the urinary bladder toward the superior and posterior margin of the prostate gland. At this point, the vas deferens en-larges slightly to form the ampulla. The duct from the accessory gland (seminal vesicle) joins it here to form the ejaculatory duct. This duct passes through the prostate gland and empties into theprostaticurethra.
The urethra extends from the urinary bladder to the tip of the penis. It is about 20 cm long (7.9 in) and passes through the prostate (prostatic urethra), con-nective tissue in the perineum (membranous ure-thra), and the penis (penile urethra).
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