penis /pē″nis/ [L, male sex organ] , the external reproductive organ of a man, homologous with the clitoris of a woman. It is attached with ligaments to the front and sides of the pubic arch and is composed of three cylindrical masses of cavernous tissue covered with skin. The corpora cavernosa penis surrounds a median mass called the corpus spongiosum penis, which contains the greater part of the urethra. The subcutaneous fascia of the penis is directly continuous with that of the scrotum, which contains the testes.
