Sexual Anatomy & Physiology

Female External Genitalia Vulva: everything that is externally visible (mons pubis, labia majora, labia minora, clitoris, urethral orifice, vaginal vestibule, perineal body) mons pubis: mound of fatty tissue above the pubic bone labia majora: large, outer fatty folds of skin tissue labia minora: inner folds of skin and erectile tissue clitoris: small, highly sensitive organ glans: tip of the clitoris prepuce (clitoral hood): loose-fitting fold of skin covering the clitoral glans

Female External Genitalia vaginal vestibule: the cleft containing the vaginal and urethral openings Skene’s glands: group of small mucous glands that open into vaginal vestibule (near urethra) Bartholin’s glands: two glands that open into vaginal vestibule (on either side of the vaginal opening) - thought to provide some lubrication, may emit a pheromone hymen: thin mucous membrane partially covering the vaginal opening perineum: tissue between the genital and anus.

External Female Genitalia

Female External Genitalia: Normal Variations

Female Internal Genitalia Vagina: tubular organ connecting external genitals with uterus Grafenberg spot (g-spot): mass of erectile and glandular tissue surrounding the urethra just below the bladder some women report that simulation to g-spot produces sexual arousal and orgasm uterus: hollow muscular organ - purpose to nurture developing fetus cervix: small lower portion of the uterus that projects into the vagina cervical os: small opening in the cervix allowing passage of fluids between the uterus and vagina myometrium: layers of smooth muscle comprising the uterus endometrium: inner lining of the uterus that builds a rich blood supply and sloughs off the lining each month (if conception does not occur)

Female Internal Genitalia ovaries: female gonads - containing the immature female reproductive cells ovum: female reproduce cell fallopian tubes: thin flexible muscular structures connecting the ovaries with the uterus - passageway for the ovum to travel to the uterus cilia: tiny hairlike projections that line the fallopian tubes and propel the ovum towards the uterus fimbriae: fringelike projections that reach out to the ovary to draw a released ovum into the fallopian tube.

Sexual Response Response to sexual stimulation involves (Masters & Johnson, 1966): vasocongestion myotonia

Female Internal Genitalia: Arteries & Veins

Female Internal Genitalia: Muscles Pelvic floor muscles Ischiocavernosus: acts to drive blood into the body of the clitoris bulbocavernosus: helps to maintain the structure of the pelvic tissue and serves as a vaginal sphincter

Internal Female Genitalia: Muscles

Female Internal Genitalia: Nerves Sexual arousal: stimulation to tactile and temperature receptors on the genitalia, breasts, etc. Orgasm: genital reflex governed by the spinal cord

Female Internal Genitalia: Nerves

Male External Genitalia penis: male copulatory organ frenulum: underside of the penis, between shaft and glans glans: enlarged conic structure at the tip of the penis corona: raised rim or ridge of tissue that separates the glans from the shaft prepuce (forskin): loose-fitting retractable casing of skin that forms over the glans smegma: accumulation of secretions on the penile glans from glands of foreskin circumcision: surgical procedure involving removal of the prepuce scrotum: skin-covered pouch containing the testes

Male External Genitalia

Male Internal Genitalia corpora cavernosa: two large and uppermost cylindrical masses of penile tissue corpus spongiosum: lower, smaller cyhlindrical mass of tissue in the penis, contains the urethra crura: tapering part of the corpora cavernosa - forms the connection to the pubic bone Testes: oval, glandular organs contained in the scrotum - produce sperm, secrete male hormones spermatic cord: suspends the testes - contains arteries, nerves, veins, vas deferens seminiferous tubules: tightly packed, convoluted structures in testicles, produce sperm interstitial cells (Leydig’s cells): located between seminiferous tubules, produce androgens

Male Internal Genitalia epididymis: tightly coiled tube lying along the top of each testis - stores spermatozoa vas deferens: structure that transports spermatozoa from testes to urethra ejaculatory ducts: short tubes that pass through prostate to urethra - passageway for semen and fluid from seminal vesicles urethra: tube for transporting urine and semen seminal vesicles: secretory glands prostate gland: secretes thin, milky, slightly alkaline fluid, rich in nutrients - into the seminal fluid - these secretions protect spermatozoa from acidic environment (male urethra, vagina) cowper’s gland: contribute alkaline fluid to semen

Cross-section of the Penis corpora cavernosa (upper left) corpus spongiosum (lower right)

Male Internal Genitalia sperm: male reproductive cell spermatogenesis: process of sperm production spermatozoon: single sperm spermatozoa: sperm, plural acrosomal cap: covering of the head of the spermatozoon - contains enzymes that penetrate the outer cover of the ovum semen: contains: seminal fluid: contains secretions from seminal vesicles, prostate gland, Cowper’s gland, and epididymis

Sperm

Male Internal Genitalia: Arteries & Veins

Male Internal Genitalia: Arteries & Veins

Male Internal Genitalia: Muscles

Male Internal Genitalia: Nerves

Sexual Response Cycle Masters and Johnson Four-Stage Model excitement plateau orgasm refractory period

Sexual Response Cycle: Excitement For both males and females excitement leads to an increase in pulse, heart rate, blood pressure and muscle tension. Similarly both sexes experience increase blood flow to the genitals and nipples. In females, the vagina becomes naturally lubricated, lengthens and widens, whilst the labia swell. In males, erection of the penis is the most obvious sign of excitment.

Sexual Response Cycle: Plateau Further increases in circulation and heart rate occur in both sexes, sexual pleasure increases with increased stimulation, muscle tension increases further. At this stage females show a number of effects. The areolae and labia further increase in size, the clitoris withdraws slightly and the Bartholin's glands produce further lubrication. Males may start to secrete seminal fluid and the testes rise closer to the body.

Sexual Response Cycle: Orgasm Orgasm is the conclusion of the plateau phase in a release of sexual tension. Both males and females experience quick cycles of muscle contraction of the anus and lower pelvic muscles, with women also experiencing uterine and vaginal contractions. Males ejaculate approximately 5-10ml of semen.

Sexual Response Cycle: Resolution The resolution stage occurs after orgasm and allows the muscles to relax, blood pressure to drop and the body to slow down from its excited state. Generally males experience a refractory period, meaning orgasm cannot be achieved again until time has passed. The penis meanwhile returns to a flaccid state. Females may not experience this refractory period and further stimulation may cause a return to the plateau stage. Otherwise, significant changes may also occur, such as the opening of the cervix and the reduction of blood flow to the genitals and nipples.

Sexual Response Cycle

Sexual Response Cycle Kaplan three-stage model (1974) sexual desire sexual excitement orgasm

Sexual Response Cycle: Sexual Desire Sexual appetite or drive sexual fantasies masturbation seek out, or be receptive to (Basson) sexual activity