The bulbocavernosus reflex (BCR) is a physiological reflex that involves the contraction of the bulbocavernosus muscle in response to stimulation of the perineum or the glans penis in males. It is named after the bulbocavernosus muscle, which is located in the pelvic floor and surrounds the base of the penis in males or the base of the clitoris in females.
The BCR is a reflex arc that involves the sensory nerves, spinal cord, and motor nerves. When the perineum or glans penis is stimulated, sensory nerve endings in the area send signals to the spinal cord. The spinal cord then relays the signals to the motor nerves that innervate the bulbocavernosus muscle, causing it to contract.
The bulbocavernosus muscle contraction serves several purposes. In males, it helps to compress the deep dorsal vein of the penis, which reduces blood outflow from the penis and helps to maintain an erection. In females, the contraction of the bulbocavernosus muscle contributes to vaginal tightening during sexual arousal and may enhance sexual pleasure.