T H E P E N I S Anatomy

T H E P E N I S Anatomy

• The penis is a sexual organ and composed of three tubular structures. The two dorsal structures, the corpora cavernosa, provide erectile function and are anchored posteriorly onto the pubic rami. The ventral tubular structure is the corpus spongiosum, which surrounds the urethra. It expands distally to form the glans penis. The corpora cavernosa have an outer tough covering of tunica albuginea. There is a septum between them. The tunica albuginea encloses the erectile tissue, which has a trabecular - structure with a network of sinusoidal spaces lined by endo - thelium within which blood pools during erection. The cen - tral arterial blood supply (cavernosal artery) is a branch of the internal pudendal artery . Sacral parasympathetic nerves are responsible for erection. They cause smooth muscle relaxation with increased arterial inflow , dilatation of the sinusoids and blood accumulation within the trabecular spaces. Simultane ously there is venous outflow occlusion by the coverings of the corpora cavernosa.

Figure 85.13 Phimosis in a child with inability to retract the prepuce.