section_path: Biological and physiological aspects/Physical anatomy and reproduction/Female anatomy and reproductive system/External female anatomy
section_name: External female anatomy
paragraph_text: External female anatomy
  
  The external female genitalia are the vulva.
  
  The mons pubis is a soft layer of fatty tissue overlaying the pubic bone. Following puberty, this area grows in size. It has many nerve endings and is sensitive to stimulation.
  
  The labia minora and labia majora are collectively known as the labia or "lips". The labia majora are two elongated folds of skin extending from the mons to the perineum. Its outer surface becomes covered with hair after puberty. In between the labia majora are the labia minora, two hairless folds of skin that meet above the clitoris to form the clitoral hood, which is highly sensitive to touch. The labia minora become engorged with blood during sexual stimulation, causing them to swell and turn red.
  
  The labia minora are composed of connective tissues that are richly supplied with blood vessels which cause a pinkish appearance. Near the anus, the labia minora merge with the labia majora. In a sexually unstimulated state, the labia minora protects the vaginal and urethral opening by covering them. At the base of the labia minora are the Bartholin's glands, which add a few drops of an alkaline fluid to the vagina via ducts; this fluid helps to counteract the acidity of the outer vagina since sperm cannot live in an acidic environment. The Skene's glands are possibly responsible for secreting fluid during female ejaculation.
  
  The clitoris is developed from the same embryonic tissue as the penis; it or its glans alone consists of as many (or more in some cases) nerve endings as the human penis or glans penis, making it extremely sensitive to touch. The clitoral glans, which is a small, elongated erectile structure, has only one known function—sexual sensations. It is the female's most sensitive erogenous zone and the main source of orgasm in women. Thick secretions called smegma collect around the clitoris.
  
  The vaginal opening and the urethral opening are only visible when the labia minora are parted. These openings have many nerve endings that make them sensitive to touch. They are surrounded by a ring of sphincter muscles called the bulbocavernosus muscle. Underneath this muscle and on opposite sides of the vaginal opening are the vestibular bulbs, which help the vagina grip the penis by swelling with blood during arousal. Within the vaginal opening is the hymen, a thin membrane that partially covers the opening in many virgins. Rupture of the hymen has been historically considered the loss of one's virginity, though, by modern standards, loss of virginity is considered to be the first sexual intercourse. The hymen can be ruptured by activities other than sexual intercourse. The urethral opening connects to the bladder with the urethra; it expels urine from the bladder. This is located below the clitoris and above the vaginal opening.
  
  The breasts are the subcutaneous tissues on the front thorax of the female body. Though they are not technically part of a woman's sexual anatomy, they do have roles in both sexual pleasure and reproduction. Breasts are modified sweat glands made up of fibrous tissues and fat that provide support and contain nerves, blood vessels, and lymphatic vessels. Their main purpose is to provide milk to a developing infant. Breasts develop during puberty in response to an increase in estrogen. Each adult breast consists of 15 to 20 milk-producing mammary glands, irregularly shaped lobes that include alveolar glands and a lactiferous duct leading to the nipple. The lobes are separated by dense connective tissues that support the glands and attach them to the tissues on the underlying pectoral muscles. Other connective tissue, which forms dense strands called suspensory ligaments, extends inward from the skin of the breast to the pectoral tissue to support the weight of the breast. Heredity and the quantity of fatty tissue determine the size of the breasts.
  
  Men typically find female breasts attractive and this holds true for a variety of cultures. In women, stimulation of the nipple seems to result in activation of the brain's genital sensory cortex (the same region of the brain activated by stimulation of the clitoris, vagina, and cervix). This may be why many women find nipple stimulation arousing and why some women are able to orgasm by nipple stimulation alone.