Figure 27

Figure 27 Mechanism of ejaculation: ejaculation is a reflex response involving both sympathetic and pudendal nerve activity. Sympathetic nerve discharge results in contraction of the bladder neck, seminal vesicles and prostate gland. Seminal fluid and prostatic secretions are emptied via the verumontanum into the prostatic urethra. Reflex relaxation of the membranous urethra and rhythmic contraction of the bulbocavernosus muscles result in the pulsatile emission of semen from the urethral meatus