Female external genitalia, and underlying tissues, artwork. At centre is the vagina, the muscular birth canal. The small opening directly above it is the urethra, the opening from the bladder, while below the vagina is the anus. Above the urethra is the clitoris, a body of erectile tissue that is homologous to the penis. The vagina is surrounded by the labia minora, which are surrounded by the labia majora. The pubic bone is at top. The purple tissue is a continuation of the clitoris, the crus of clitoris. The bulb of the vestibule (blue) also consists of erectile tissue and grips the penis during intercourse. Below this is Bartholin's gland, which secretes mucus to lubricate the vagina.