section_path: Biological and physiological aspects/Physical anatomy and reproduction/Male anatomy and reproductive system/External male anatomy
section_name: External male anatomy
paragraph_text: External male anatomy
  
  The external male genitalia are the penis and the scrotum.
  
  The penis provides a passageway for sperm and urine. The penis consists of nerves, blood vessels, fibrous tissue, and three parallel cylinders of spongy tissue. Other components of the penis include the shaft, glans, root, cavernous bodies, and spongy body. The three cylindrical bodies of spongy tissue, which are filled with blood vessels, run along the length of the shaft. The two bodies that lie side by side in the upper portion of the penis are the corpora cavernosa (cavernous bodies). The third, called the corpus spongiosum (spongy body), is a tube that lies centrally beneath the others and expands at the end to form the tip of the penis (glans). During arousal, these bodies erect the penis by filling with blood.
  
  The raised rim at the border of the shaft and glans is called the corona. The urethra connects the urinary bladder to the penis where urine exits the penis through the urethral meatus. The urethra eliminates urine and acts as a channel for semen and sperm to exit the body during sexual intercourse. The root consists of the expanded ends of the cavernous bodies, which fan out to form the crura and attach to the pubic bone and the expanded end of the spongy body. The bulb of the penis is surrounded by the bulbospongiosus muscle, while the corpora cavernosa are surrounded by the ischiocavernosus muscles. These aid urination and ejaculation. The penis has a foreskin that typically covers the glans; this is sometimes removed by circumcision for medical, religious or cultural reasons. In the scrotum, the testicles are held away from the body, one possible reason for this is so sperm can be produced in an environment slightly lower than normal body temperature.
  
  The penis has very little muscular tissue, and this exists in its root. The shaft and glans have no muscle fibers. Unlike most other primates, male humans lack a penile bone.