Answer
The penis is the male sex organ whose function is to deposit semen/sperms into the vagina. Structurally the penis comprises three parts-- the internal root, the external shaft, and the glans at the distal end of the shaft --the glans is an expanded structure that has the external orifice of the urethra at its tip.
The skin of the penile shaft is loosely attached and this facilitates expansion (swelling) of the shaft during erection. The prepuce ( foreskin) is the unattached distal portion of the penile skin that comes over the glans . Its removal is called during circumcision.
The frenulum is a ventral fold of skin that attaches the prepuce to the proximal aspect of the glans. The glans and prepuce have sebaceous glans that secrete a greasy fluid called smegma.
The shaft of the penis has three erectile cylinders-- one ventral corpus spongiosum and two lateral corpora cavernosa. All three bodies of erectile tissues are spongy and highly vascular, with many small blood sinuses. These sinuses or lacunae are separated by trabeculae (small bars or beams) of smooth muscle and connective tissue. When the penis is flaccid the lacunae appear as small slits --collapsed by the tone of the trabecular muscles.
At the body surface the penis (shaft) turns 90% posteriorly and continues into the pelvic cavity as the root.
Work Step by Step
The corpus spongiosum ends internally as a dilated bulb. The corpora cavernosa diverge into a "Y" shaped structure. Each arm is called a crus attaches the penis to an ischiopubic ramus and and the perineal membrane on its side
