The perineum is an anatomical region located between the thighs and represents the most inferior part of the pelvic outlet. It is the thin layer of skin between the genitals (vaginal opening or scrotum) and anus. The perineum is separated from the pelvic cavity superiorly by the pelvic floor. It contains structures that support the urogenital and gastrointestinal systems and plays an important role in functions such as micturition, defecation, sexual intercourse, and childbirth.

The perineum is an erogenous zone and contains multiple nerve endings that help with sexual arousal and response. Inside the body, the perineum consists of tissue that makes up the bottom of the pelvic cavity and contains structures that help with urination, defecation, and intercourse. In females, the perineum contains structures that help with vaginal birth.

Perineal injury is an injury to the perineum, the area of the body between the anus and the scrotum in males or the opening of the vagina and the anus in females. Injuries to the perineum can happen suddenly, known as an acute injury, or gradually, known as a chronic injury. Signs of a perineal injury include bleeding or an open wound, object embedded in the perineum, burned skin, bruising, swelling, fresh blood in the urethral opening, and inability to urinate.

The perineal body is an irregular fibromuscular mass located at the junction of the urogenital and anal triangles, the central point of the perineum. It contains skeletal muscle, smooth muscle, and collagenous and elastic fibers. The perineal body helps strengthen the pelvic floor and acts as a point of attachment for muscle fibers.