The two corpora cavernosa and corpus spongiosum (also known as the corpus cavernosum urethrae in older texts and in the adjacent diagram) are three expandable erectile tissues along the length of the penis, which fill with blood during penile erection. The two corpora cavernosa lie along the penis shaft, from the pubic bones to the head of the penis, where they join. These formations are made of a sponge-like tissue containing trabeculae, irregular blood-filled spaces lined by endothelium and separated by septum of the penis.
