Cultural expectations of male sexuality inhibit many men from seeking help for a disorder that can, in most cases, benefit from medical treatment. The condition is normal and usually temporary, so it is highly unfortunate that the common term for it implies a sweeping diminution in a man's overall capabilities. The Structure of the Penis. A central chamber called the corpus spongiosum , which contains the urethra, the tube that carries urine from the body Erectile Tissue. These structures are made up of erectile tissue .
Erectile tissue is rich in tiny pool-shaped blood vessels called cavernous sinuses .
Each of these vessels are surrounded by smooth muscles and supported by elastic fibrous tissue composed of a protein called collagen . The penis is either flaccid or erect depending on the state of arousal. Small arteries leading to the cavernous sinuses contract, reducing the inflow of blood. The smooth muscles regulating the many tiny blood vessels within the penis are also contracted. These chemicals relax the smooth muscles in the penis.