Sonographic penile anatomy
The penis is composed of two dorsal corpora cavernosa and one ventral corpus spongiosum. The two corpora cavernosa are enclosed in a fibrous sheath, the tunica albuginea, which partially covers the corpus spongiosum. The tunica albuginea is composed of elastic fibers that form an irregular, criss-crossing strips network on which collagen fibers rest. The corpora cavernosa are composed of sinusoidal spaces lined by smooth muscles (erectile tissue) and endothelium. The glans penis is formed by expansion of the corpus spongiosum. The corpus spongiosum is traversed throughout its length by the anterior urethra, which begins at the perineal membrane. The corpus spongiosum provides support to the urethra and helps with the expulsion of semen from the urethra. Buck's fascia surrounds both cavernosal bodies dorsally and splits to surround the spongiosum ventrally (Figure 1a and b). The penile blood vessels arise from the internal pudendal artery. The penile artery divides into two main branches, the dorsal penile artery and the cavernosal artery. The cavernosal artery enters the corpus cavernosum on the superomedial surface of the penis. The branches of this artery are called the helicine arteries and subsequently divide into smaller vessels that communicate with the lacunae of the corpus cavernosum (Figure 1c and d). The venous blood is returned by the venous plexus beneath the tunica albuginea. The emissary veins perforate the tunica albuginea, and the blood is drained by the venae circumflexae into the deep dorsal veins.
Normal sonogram of penis. (a) Transverse gray-scale ultrasound of the penis demonstrates the two corpora cavernosa (CC) surrounded by the tunica albuginea (arrowhead). The corpus spongiosum (CS) is seen inferior to the corpora cavernosa. All three corpora are surrounded by the Buck's fascia (arrow). (b) The corresponding line diagram. (c) Longitudinal color flow Doppler ultrasound of normal cavernosal bodies and flow through cavernosal artery (arrow) and the helicine branches (arrowheads). (d) The corresponding line drawing of the blood supply to the penis.
Int J Impot Res. 2007;19(1):37-42. © 2007
Nature Publishing Group
Cite this: Doppler Evaluation of Erectile Dysfunction - Part 1 - Medscape - Jan 01, 2007.