Sexual Anatomy & Physiology

Sexual Anatomy & Physiology
Presentation by: Dr. Penny Frohlich
University of Texas at Austin

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
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.

Normal Variations

Female Internal Genitalia
Vagina: tubular organ connecting external genitals with uterus
Grafenberg spot (g-spot):

o mass of erectile and glandular tissue surrounding the urethra just below the bladder
o 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)

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
Arteries & Veins
Female Internal Genitalia: Muscles

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

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

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

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
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)
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:

spermatozoa: sperm, plural
seminal fluid: contains secretions from seminal vesicles, prostate gland, Cowper’s gland, and epididymis

Arteries & Veins
Male Internal Genitalia: Muscles
Male Internal Genitalia: Nerves
Sexual Response Cycle

* Masters and Johnson Four-Stage Model
o excitement
o plateau
o orgasm
o 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.
* 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

* Kaplan three-stage model (1974)
o sexual desire
o sexual excitement
o orgasm

Sexual Desire

* Sexual appetite or drive
o sexual fantasies
o masturbation
o seek out, or be receptive to (Basson) sexual activity


Sexual Anatomy & Physiology.ppt