- During sexual stimulation the brain sends signals to the nerves in the spinal cord. The signals cause the nerves to stimulate the pelvic muscles, causing them to contract. The pelvic contractions encourage the sperm to leave the testes and go through the vas deferens, seminal vesicle and prostate gland. From there it travels through the urethra, where it is forcefully released through the tip of the penis.
- Although ejaculation is commonly caused by sexual stimulation, it can also occur during sleep without sexual stimulation, called nocturnal emission. Nocturnal emissions typically occur during a man's teenage years when he is going through puberty. According to KnowledgeRush.com, ejaculation is also caused when the prostate gland is massaged. Prostate disease also can cause involuntary ejaculation.
- The time ejaculation occurs after sexual stimulation varies--some men ejaculate only after five minutes, whereas others can go for an hour or more. Sexual dysfunctions, such as premature ejaculation or delayed ejaculation, can significantly decrease or increase the time between the start of sexual stimulation and ejaculation.
- Men typically release 5 to 15 milliliters of semen during each ejaculation. This amount decreases or increases based on the time since the last ejaculation, the warmth of the testicles, the degree of sexual excitement, testosterone levels, age and the man's general fertility level.
- Dysfunctions that affect ejaculation include premature ejaculation, retarded ejaculation and retrograde ejaculation. According to the Cleveland Clinic, the most common dysfunction is premature ejaculation, which causes ejaculation to occur before or shortly after penetration. Retarded ejaculation is when ejaculation does not occur after orgasm. Retrograde ejaculation is caused when the semen travels back into the bladder during orgasm.
