Posted by lae2 on September 15, 2009 at 22:38:58:
In Reply to: Attempts/Answers to Pelvic Nerves/Vessels posted by Matt Oglesby on September 14, 2009 at 21:21:26:
: 1.Sacral splanchnic nerves and pelvic splanchnic nerves are, in fact, the same nerves.
: False. Sacral splanchnic and pelvic splanchnic nerves are not synonymous with each other. The Sacral provide sympathetic innervation whereas the pelvic supply parasympathetic.
FALSE is the intended answer.
: 2.Parasympathetic preganglionic cell bodies that mediate contraction of the detruser muscle are located in the intermediolateral cell column at levels L1-2.
: False. Sympathetic efferent neurons have their cell bodies in the intermediolateral cell columns; and parasympathetic neurons would not come out of the region of L1-2, that region is designated for sympathetic outflow (T1-L2).
FALSE is the intended answer. Preganglionic cell bodies that mediate contraction of the detrusor are located in the IMLCC of S2-4.
: 3.Peristalsis of the hindgut is driven by the parasympathetic division of the autonomic nervous system.
: True. Rest n' Digest are guided through the parasympathetic division.
TRUE is the intended answer.
: 4.Relaxation of the external anal sphincter and the puborectalis is driven by the somatic nervous system.
: True. These are skeletal muscles, and as such, are controlled via the somatic division.
TRUE is the intended answer.
: 5.The helicine arteries dilate in response to parasympathetic activity.
: True. Helicine arteries are arterial branches into the corpora cavernosa that aid in engorging the tissue with blood during an erection (both male and female).
TRUE is the intended answer.
: 6.The bulbospongiosus and the ischiocavernosus muscles contract in response to the somatic nervous system.
: True. These are skeletal muscles of the urogenital diaphragm and are controlled through somatic innervation.
TRUE is the intended answer.
: 7.Peristalsis of the vas deferens is driven by sympathetic nerves from the pelvic plexus.
: True. During ejaculation, sperm is moved out of the testes via the Vas Deferens by way of sympathetic innervation. The pelvic plexus contains both sympathetic and parasympathetic neurons. It is the pelvic splanchnic nerves which are solely parasympathetic.
TRUE is the intended answer.
: 8.The cerebral release mechanism for urination is mostly driven by the somatic nervous system.
: True. Branches of the pudendal nerve control the external urethral sphincter and the levator ani muscles. These are skeletal muscles that need to be relaxed for micturition to take place. The levator ani will allow the urinary bladder to descend, thus releasing pressure on the uvular region, and the external urethral sphincter will allow the urine to urine to exit to the external urethral orifice.
TRUE is the intended answer. Nevertheless, do not rule out the possibility that the cerebral release mechanism activates preganglionic parasympathetic nerves that mediate contraction of the detrusor.
: 9.Both the true urethral sphincter and the function urethral sphincter (uvula) are driven by the somatic nervous system.
: False. The true urethral sphincter pertains to the external urethral sphincter, which is skeletal muscle, and is thus controlled by the somatic nervous system. Whereas the functional urethral sphincter pertains to the internal urethral sphincter, which is smooth muscle, and is controlled by the autonomic division of the nervous system.
TRUE is the intended answer. Perhaps not the best question. I was referring to the uvula as part of a functional sphincter. Relaxing the levator ani is mediated by the somatic nervous system and is thought to open the prostatic urethra at the uvula.
: 10.Sensation from the glans of the penis/clitoris is mediated by the autonomic nervous system.
: False. Sensation is mediated by the somatic nervous system. The afferents of the autonomic nervous system are known as the “visceral afferents” or the “enteric nervous system.”
FALSE is the intended answer.
: 11.The sacral splanchnic nerves contribute to the inferior hypogastric plexus.
: True. Other contributing members of the inferior hypogastric plexus include the lumbar splanchnic nerves and the pelvic splanchnic nerves. The pudendal nerve does not contribute.
TRUE is the intended answer. Please note, however, that the lumbar splanchnic nerves do not provide a direct anatomical pathway to the inferior hypogastric plexus as do the sacral and pelvic splanchnic nerves. Instead, fibers derived from lumbar splanchnic nerves contribute directly to the aortic plexus. Then some of these fibers travel through the superior hypogastric plexus and finally the right and left hypogastric nerves to arrive at the inferior hypogastric plexus.
: 12.The pelvic splanchnic nerves contribute to the inferior hypogastric plexus.
: True. See explanation for #11.
TRUE is the intended answer.
: 13.The right and left hypogastric nerves contribute to the inferior hypogastric plexus.
: True. Although the inferior hypogastric plexus is inferior to the left/right hypogastric nerves—neurons may run either way, it's a two-way street.
TRUE is the intended answer. Indeed, there are visceral afferent fibers and autonomic efferent fibers in the hypogastric nerves. In fact, the left hypogastric nerve is host to parasympathetic fibers ascending from the pelvis.
: 14.Gray rami from the sacral sympathetic trunk contribute to the inferior hypogastric plexus.
: True. They give rise to the sacral splanchnic nerves as well.
FALSE is the intended answer. Gray rami, as always, communicate with the sacral spinal nerves (by way of the ventral rami). This is key to answering the never ending question about innervation to dartos (smooth muscle).
: 15.White rami from the sacral sympathetic trunk contribute to the inferior hypogastric plexus.
: False. There are no white rami outside of vertebral levels T1-L2 (although in class, we keep saying L3; I need clarification on this).
FALSE is the intended answer. Certainly L2 and maybe L3.
: 16.Nerve fibers derived from the lumbar splanchnic nerves contribute to the inferior hypogastric plexus.
: True. Lumbar splanchnic, Sacral splanchnic, and Pelvic Splanchnic all contribute to the inferior hypogastric plexus.
TRUE is the intended answer. Be aware that the lumbar splanchnic nerves are anatomical structures. It is nerve fibers conveyed by the lumbar splanchnic nerves that find their way to the inferior hypogastric plexus. Lumbar splanchnic nerves directly contribute to the aortic plexus. This is why I stated "derived from."
: 17.The uterine autonomic plexus receives contributions from the inferior hypogastric plexus.
: Most likely true. While this information was not readily accessible in my references, I believe it to be the case since the visceral plexuses of the pelvic cavity obtain their innervation from the inferior hypogastric, pelvic, and sacral plexuses.
TRUE is the intended answer. The uterus also receives innervation from the internal iliac plexus. Specifically, the uterine arterial plexus.
: 18.The uterine autonomic plexus receives contributions from the internal iliac plexus.
: While this could be true, I'd say it is unlikely since I already answered yes to the previous question...and I don't know how much innervation one uterus really needs.
TRUE is the intended answer. Note that the right and left hypogastric nerves can be sectioned as a treatment for intractable uterine pain without noticeable deleterious effects on the autonomic functions of the pelvic viscera.
: 19.The hypogastric nerves contain both pre- and post-ganglionic sympathetic nerves (this is true).
: I agree.
TRUE is the intended answer. Preganglionic fibers are from lumbar splanchnic nerves that have not "found" a ganglion of postganglionic cell bodies. Nevertheless, they will synapse in microscopic ganglia prior to the the viscera.
: 20.The cavernous nerves pass through the urogenital diaphragm to arrive in the perineum.
: “Most likely the case.” The parasympathetic cavernous nerves innervate the smooth muscle surrounding the helicine arteries, allowing for vasodilation and subsequent erection of the penis/clitoris. In order for nerves to breach this region, they most likely pass through the perineum.
TRUE is the intended answer. Robotic surgical techniques claim to cause less damage to the cavernous nerves than standard surgical techniques. If you happen to need prostate surgery; shop for a surgeon and a hospital.
: 21.Pelvic splanchnic nerves, by way of the inferior hypogastric plexus, contribute to the cavernous nerves.
: True. Based on the fact that Pelvic splanchnic nerves are some of the few contributors of parasympathetic innervation in the immediate area, these guys are most likely responsible for supplying the erection-causing cavernous nerves.
TRUE is the intended answer. The prostatic autonomic plexus intervenes.
: 22.Surgical resection of the prostate may damage the cavernous nerves.
: True. Pelvic splanchnic nerves pass through the prostatic plexus en route to the penis. If a prostatectomy is performed, these nerves risk being damaged.
TRUE is the intended answer.
: 23.Peristalsis at the left colic flexure is indirectly inhibited by lumbar splanchnic nerves.
: True. Lumbar splanchnic nerves are sympathetic and inhibit actions of digestion.
TRUE is the intended answer. I used "indirectly" to allow that the preganglionic fibers must act on postganglionic fibers. It is the postganglionic fibers that directly provide inhibition.
: 24.Peristalsis at the left colic flexure is indirectly activated by sacral splanchnic nerves.
: False. Sacral splanchnic nerves are sympathetic and will inhibit digestion.
FALSE is the intended answer. Pelvic splanchnic nerves do this.