Structure
The penis consists of 3 bodies of erectile tissue:
- Bulb (becomes the corpus spongiosum)
- Crura (becomes the paired corpora cavernosa)
The bulb is a midline structure attached to the undersurface of the urogenital diaphragm. It contains the urethra. As the bulb progresses forward it becomes the ventrally orientated corpus spongiosum.
There is a left crus and right crus that are attached to the pubic arch and covered by the ischiocavernosus muscle. These crura become the paired dorsal corpora cavernosa as they progress forward.
Innervation
- Pudendal nerve & pelvic plexus
- Nerve supply derived from S2-S4*
Sensory and sympathetic innervation is provided by the dorsal nerve of penis (terminal branch of pudendal nerve - seen lateral to dorsal artery in image below). The dorsal nerve of penis supplies the skin and glans. Ilioinguinal nerve branches contribute some sensory fibres to supply the skin at the root of the penis. Parasympathetic innervation is provided by cavernous nerves from the pelvic plexus (aka inferior hypogastric plexus).
*RCEM syllabus highlights S2 as the primary spinal segment for penile innervation
