Editing Penis (section)

== Gross Structure ==

* '''<span style="color:#ff0000">With the penis on stretch in a standing position, the superior surface of the penis is known as the dorsum and the inferior surface, is known as the ventrum</span>'''
* The shaft of the penis and the base of the glans are separated by the corona
* '''<span style="color:#ff0000">Layers surrounding the corpora cavernosa, from superficial to deep (5):</span>'''
*# '''<span style="color:#ff0000">Skin</span>'''
*# '''<span style="color:#ff0000">Dartos (continuous with Scarpa’s and Colle’s fasciae)</span>'''
*# '''<span style="color:#ff0000">Tela subfascialis (very thin connective tissue layer)</span>'''
*# '''<span style="color:#ff0000">Buck’s fascia</span>'''
*# '''<span style="color:#ff0000">Tunica albuginea</span>'''
[[File:Penis_Anatomy_Cross_Section.png|center|frameless|644x644px]]

=== Corpus cavernosum ===

* '''The erectile bodies; comprised of 2 spongy, paired cylinders'''
* '''Contained in the tunica albuginea'''
** '''The erectile tissues of the normal corpora cavernosa are separated from the tunica by the space of Smith'''
* '''Proximal ends, the crura, originate at the undersurface of the puboischial rami as separate structures but merge under the pubis to form the body of the penis and remain attached up to the glans'''
* '''<span style="color:#ff0000">A septum separates the corpora cavernosa but is permeable distally to allow for free communication between their vascular spaces</span>'''
[[File:Wiki_Penis_Base_Cross_Section.jpg|alt=Wiki Penis Base Cross Section|center|frameless|503x503px]]
* '''Each corpus cavernosum is a conglomeration of sinusoids,''' larger in the center and smaller in the periphery.
** '''In the flaccid state, the blood slowly diffuses from the central to the peripheral sinusoids, and the blood gas levels are similar to those of venous blood.'''
** '''During erection, the rapid entry of arterial blood to both the central and the peripheral sinusoids changes the intracavernous blood gas levels to those of arterial blood'''

=== Corpus spongiousum ===

* The urethra travels through the corpus spongiosum, with its proximal segment known as the bulb.
* '''<span style="color:#ff0000">The glans penis is an expansion of the corpus spongiosum</span>'''

=== Tunica albuginea ===

*Tough connective tissue layer composed primarily of type I collagen
* '''A bilayered structure (inner circular, outer longitudinal)''' with multiple sublayers.
** '''<span style="color:#ff0000">Outer longitudinal layer</span>'''
***'''<span style="color:#ff0000">Completely absent on the ventral groove between the 5 and 7 o'clock positions.</span>'''
****'''The most vulnerable area in the tunica albuginea'''
*****'''Most prostheses tend to extrude here''' 
****'''<span style="color:#ff0000">The lack of tunica albuginea on the ventral groove may contribute to greater ease of dorsal buckling and explain why most PD patients exhibit dorsal curvature</span>'''
*****'''<span style="color:#ff0000">60-70% of plaques are located on the dorsal aspect of the penis</span> and are usually associated with the septum'''
*'''Covers the corpora cavernosa and *spongiosum'''
**'''*The corpus spongiosum lacks an outer longitudinal layer''' or intracorporeal struts, '''ensuring a low-pressure structure during erections'''

=== Buck fascia ===

* '''<span style="color:#ff0000">External to the tunica albuginea</span>'''
* '''Surrounds corpora cavernosae; ventrally, splits to surround the corpus spongiosum'''
* '''Distally, fuses with the glans at corona'''
* '''<span style="color:#ff0000">The paired dorsal arteries, paired dorsal nerves, and deep dorsal vein are deep to Buck’s fascia</span>'''
* '''<span style="color:#ff0000">The superficial dorsal penile vein is external to Buck’s fascia</span>'''
* '''<span style="color:#ff0000">A penile fracture is a tear in the tunica albuginea; the hematoma is contained by Buck’s fascia</span>'''

=== Penile skin ===

* Very elastic 
* '''Only glandular elements are the smegma-producing glands, called glands of Tyson, located at the base of the corona'''

=== External penile support ===

* '''Consists of 2 ligamentous structures: the fundiform and suspensory ligaments'''
** '''The fundiform ligament arises from Colles fascia''' and is lateral, superficial, and not adherent to the tunica albuginea of the corpora cavernosa.
** '''The suspensory ligament arises from Buck fascia''' and consists of two lateral bundles and one median bundle