Erectile Tissue

The body, or shaft, of the penis is composed of three columns of erectile tissue. These include a pair of "corpora cavernosa" near the back and a single "corpus spongiosum" below. These columns are enclosed by skin, a thin layer of subcutaneous tissue, and a layer of connective tissue. In addition, each column is surrounded by a tough capsule of white fibrous connective tissue. The corpus spongiosum, through which the urethra extends, is enlarged at the end to form a sensitive, cone-shaped "glans penis," which covers the ends of the corpora cavernosa and bears the urethral opening. Inside the glans penis, the corpus spongiosum is dilated and forms the "navicular fossa."