Creed K E
School of Veterinary Studies, Murdoch University, Western Australia.
J Smooth Muscle Res. 1995 Feb;31(1):1-4. doi: 10.1540/jsmr.31.1.
The lower urinary tract in mammals consists of the bladder, a storage organ for urine, and the urethra through which urine is expelled to the outside. In the male the urethra extends outside the body as the penis. The lower urinary tract is innervated by pelvic (parasympathetic) nerves and hypogastric nerves which combine on each side at the pelvic plexus. Fibres pass to the bladder, urethra, genital organs, rectum and blood vessels. In addition to the pelvic and hypogastric nerves there is sacral outflow to skeletal muscle, such as the external sphincters of the urethra and anus, in the pudendal nerve and the sympathetic chain extends caudally with branches lying in the sacral outflow that supply the penis and other organs though not the bladder. Bladder evacuation and penile erection are produced by activity of the pelvic nerves whereas sympathetic activity usually dominates during urine storage and penile flaccidity, though it may not be essential for either.
哺乳动物的下尿路由膀胱（一个储存尿液的器官）和尿道组成，尿液通过尿道排出体外。在男性中，尿道作为阴茎延伸到体外。下尿路由盆腔（副交感神经）神经和腹下神经支配，这些神经在盆腔丛处两侧合并。纤维通向膀胱、尿道、生殖器官、直肠和血管。除了盆腔神经和腹下神经外，还有骶部传出神经支配骨骼肌，如尿道和肛门的外括约肌，阴部神经中的交感神经链尾端延伸，其分支位于骶部传出神经中，为阴茎和其他器官（但不包括膀胱）供血。膀胱排空和阴茎勃起是由盆腔神经的活动产生的，而交感神经活动通常在尿液储存和阴茎疲软期间占主导地位，不过这两者可能都不是必需的。
