Editing Normal Erectile Physiology (section)

=== Spinal centers and peripheral pathways ===
* '''<span style="color:#ff0000">Neural pathways necessary for complete sexual function:</span>'''
** '''<span style="color:#ff0000">Autonomic</span>'''
*** '''<span style="color:#ff0000">Parasympathetic</span>'''
*** '''<span style="color:#ff0000">Sympathetic</span>'''
** '''<span style="color:#ff0000">Somatic (sensory and motor)</span>'''

==== Autonomic ====
* '''<span style="color:#ff0000">Parasympathetic</span> ('''lateral horns '''<span style="color:#ff0000">S2-S4</span>)'''
** '''<span style="color:#ff0000">Responsible for tumescence</span>''' '''(increasing rigidity)'''
** The parasympathetic preganglionic fibers pass in the pelvic splanchnic nerves to the inferior hypogastric plexus (also known as the pelvic plexus)
* '''<span style="color:#ff0000">Sympathetic</span> ('''lateral horns '''<span style="color:#ff0000">T10-L2</span>)[https://www.nature.com/articles/3901188]'''
** '''<span style="color:#ff0000">Responsible for detumescence</span>''' '''(decreasing rigidity)'''
** The lumbar sympathetics from the superior hypogastric plexus (in older texts, hypogastric plexus or presacral nerve) travel to the inferior hypogastric plexus via the hypogastric nerve
** The sympathetic postganglionic fibers pass in the sacral splanchnic nerves from the sympathetic chain to the inferior hypogastric plexus
* '''<span style="color:#ff0000">The sympathetic and parasympathetic nerves merge in the inferior hypogastric/pelvic plexus to form the paired cavernous nerves, which enter the corpora cavernosa and corpus spongiosum and innervate the penis</span>'''
** '''Clinical implication: nerve-sparing prostatectomy aims to avoid injury to the cavernous nerves.'''

==== Somatic ====
* '''<span style="color:#ff0000">Center of somatomotor penile innervation (also motorneurons for external urinary sphincter) is in S2-S4 spinal cord region and is called Onuf's nucleus</span>'''
* '''<span style="color:#ff0000">Onuf nucleus (S2-S4)</span>'''
** '''<span style="color:#ff0000">Nerve fibers from neurons in Onuf's nucleus travel in the sacral nerves to become the pudendal nerve (S2-S4).</span>'''
** '''<span style="color:#ff0000">Pudendal nerve</span>'''
*** '''<span style="color:#ff0000">A mixed nerve (both sensory and motor components)</span>'''
*** Throughout most of its path, the nerve is closely associated with the branches of the internal pudendal artery and vein.[https://www.ncbi.nlm.nih.gov/books/NBK554736/]
***'''<span style="color:#ff0000">Responsible for (3):</span>'''
***# '''<span style="color:#ff0000">Penile sensation</span>'''
***#* The nerve fibers from the sensory receptors in the '''penile skin, glans, and urethra and within the corpus cavernosum''' converge to form bundles of the dorsal nerve of the penis, which joins other nerves to become the pudendal nerve
***# '''<span style="color:#ff0000">Contraction of the ischiocavernosus muscle</span>'''
***#* '''Produces the rigid-erection phase'''
***# '''<span style="color:#ff0000">Contraction of the bulbocavernosus/bulbospongiosus muscles (and external urethral sphincter)</span>'''
***#*'''Rhythmic contraction and compression on the proximal corpus spongiosum helps expel semen'''
*** Enters the spinal cord via the S2-S4 roots to terminate on spinal neurons and interneurons in the central gray region of the lumbosacral segment. Activation of these sensory neurons sends messages of pain, temperature, and touch by means of spinothalamic and spinoreticular pathways to the thalamus and sensory cortex for sensory perception