How Does Ejaculation Occur?

Ejaculation is controlled by the body’s central nervous system and occurs when sexual stimulation combined with a certain degree of friction, creates impulses that are sent to the spinal cord and up into the brain. The brain then sends signals back down the spinal cord to the genital area, signals that cause the pelvic muscles to start contracting.

When this happens, phase one of ejaculation kicks in: the tubes that store and transport sperm from the testicles (or testis as they’re also called) start to contract to squeeze the sperm through the prostate gland and towards the base of the penis. During this same process, two glands behind the bladder – called the seminal vesicles – release a secretion that’s rich in fructose, or sugar, and provides the sperm with the energy it needs to move. This fluid combines with the sperm to make semen, which is what makes up most of the volume in a man’s ejaculate.

Once this has happened, ejaculation becomes an unstoppable force and the process moves on to phase two, when muscles at the base of the penis begin to contract to force the semen up through the urethra and out of the penis.

Not all ejaculations result in a forceful expulsion of semen. Some may dribble out of the penis while others may shoot quite a distance from the body. This may be due to the frequency of ejaculations in the same day or sexual arousal state during ejaculation, the man’s health and his age.