The human penis is an external male sexual organ that additionally serves as the urinal duct. In uncircumcised men a fold of skin, the foreskin, covers the head of the penis.
The body of the penis is made up of three columns of tissue: two corpora cavernosa, which contain the erectile tissue that allows the penis to get hard during an erection, and the corpus spongiosum.
The human male urethra passes through the prostate gland, where it is joined by the ejaculatory duct, and then through the penis. The urethra traverses the corpus spongiosum, and its opening, the meatus lies on the tip of the glans penis. It is a passage both for urine and for the ejaculation of semen.
Disorders of the penis treated by Dr Timothy Nathan include: