peenis

The penis is the external male reproductive and urinary organ in humans. It functions in urination and in sexual reproduction by delivering semen into the vagina during intercourse. The visible portion includes the shaft and the glans, and many people have a foreskin that covers the glans; this foreskin may be removed by circumcision in some individuals or populations.

Anatomy: The penis contains three cylindrical columns of erectile tissue: two corpora cavernosa on the dorsal side and one corpus spongiosum ventrally. The urethra runs through the corpus spongiosum to the glans. The skin is thin and richly innervated. Blood supply comes from the pudendal arteries; erection arises when sexual arousal triggers the relaxation of smooth muscle and increased arterial inflow, leading to engorgement of the erectile tissues and restricted venous outflow. Nerve fibers provide sensation and autonomic inputs.

Development and variation: The penis develops from the embryonic genital tubercle and becomes more prominent at puberty under testosterone. Size and shape vary widely among individuals. Common conditions include phimosis (tight foreskin), balanitis (inflammation of the glans), curvature (Peyronie disease), and, rarely, penile cancer.

Health and safety: Maintain good hygiene; HPV vaccination reduces risk of related cancers. Seek medical advice for persistent pain, lump, discharge, or an erection lasting more than four hours (priapism), or for urination difficulties.