Human penis
The human penis is an external genital organ containing the urethra. It conducts urine and can deliver semen during sexual reproduction.
Corpora cavernosa: Two columns of erectile tissue that run along the penis and fill with blood during erection. These paired structures provide most of the rigidity of an erection.
Erection: An enlargement and stiffening of erectile tissue, usually caused by increased blood flow and restricted venous outflow. It is the vascular change that makes penile penetration possible.
Erectile dysfunction: Persistent difficulty achieving or maintaining an erection sufficient for satisfactory sexual activity. It is a common disorder of penile function with vascular, neurological, hormonal, or psychological causes.
Clitoris: An erectile organ of the vulva with extensive internal tissue and a highly sensitive glans. It shares developmental origins and erectile tissue with the penis but has a different anatomy and role.
Corpus spongiosum: A column of erectile tissue surrounding the penile urethra and expanding into the glans. It surrounds the urethra and helps keep it open during erection.
Penile erection physiology: The neural, vascular, and tissue processes that produce and maintain a penile erection. It explains how nitric oxide and smooth-muscle relaxation change penile blood flow.
Peyronie's disease: A condition in which fibrous scar tissue in the penis causes curvature or deformity, especially during erection. Scar tissue can alter the shape and function of the erect penis.
Penis (animal): An intromittent reproductive organ found in many animal species, with anatomy that varies widely. Comparing species reveals which human penile features are shared and which are distinctive.
Glans penis: The sensitive expanded tip of the penis, continuous with the corpus spongiosum. This structure forms the organ’s tip and contains many sensory nerve endings.
Ejaculation: The expulsion of semen from the urethra, typically through coordinated emission and expulsion phases. It is the process that moves semen through the penis and out of the body.