Bio 290 The Perineum - dr. gobetz PDF

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Bio 290 The Perineum  perineum - inferior most region of the body o levator ani divides perineum from the pelvic cavity o superficial to the pelvic diaphragm  urogenital diaphragm - -transverse perineum muscle o composed of hypaxial muscles and connective tissue o functions to anchor and move the structures labeled below o contains two voluntary sphincters (external urethral sphincter muscle and external anal sphincter muscle)  external genitalia - consists of masses of erectile tissues and associated hypaxial muscles o lie under skin but inferior to transverse perineal muscle  erectile tissue masses of females - composed of corpus spongiosum tissue o bulbs of vestibule o glans clitoris  composed of corpus cavernosum tissue o crus of the clitoris  hypaxial muscles of men and females - associated with structures at left o bulbospongious muscles o ishiocavernous muscle  scrotum - external skin around the testes  erectile tissue masses of males o composed of corpus spongiosum tissue  bulb of penis  glans penis o crura of the penis is composed of corpus cavernosum  common iliac artery - bifurcates into 2 arteries in the pelvic region o 1. external iliac artery that supplies the lower limbs o 2. internal iliac artery that supplies the pelvic viscera, genitalia, buttocks, and superior part of the inner thigh  innervation of pelvic viscera and perineum - pudenal nerve  foramina in the pelvic viscera – o 1. greater sciatic foramen o 2. obturator foramen  how to gonads and celoms end up in their respective locations in the males and females o 1. descent of the gonads both tsetse and ovaries o 2. formation of a celom surrounding each testis in the scrotal sac o 3. the anatomy and function of three sets of tubes  a: ureter in males and females  b: ductus deferens in males  c: uterine tubes, uterus, and vagina in females  homologous structures - Structures in different species that are similar because of common ancestry.

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o male and female gonads develop from the same embryonic precursor where do testes and ovaries begin development? - in the posterior body wall at segmental level T10 homologous parts in males – o bulbs of vestibule o -glans of penis o -crura of penis o -testes o -scrotum homologous parts in females – o bulbs of vestibule o -glans clitoris o -crura of clitoris o -ovaries o -labia majora inguinal canal - present in both males and females o the gonads descend through a specific structure that acts as a passageway o balloon like evagination of hypaxial body wall layers o tunnel of body wall layers that form a channel for the testes to descend and end up outside o ovaries never pass through the inguinal canal o provides an entrance into the scrotal pouch in males and the labia majora in females o inguinal canal is vestigial in females perineum - body region inferior to the pelvic diaphragm o bounded by pubic symphysis anteriorly o bounded to coccyx posteriorly o bounded to ischial tuberosity laterally o anterior urogenital triangle and posterior anal triangle urogenital triangle -penetrated by urethra and vagina o transverse perineal muscle (composed of a superficial and deep part separated by a membrane) o external urethral sphincter muscle (surrounds urethra) o external genitalia central tendon - connects the transverse perineal mm and external anal sphincter m o connective tissue between the transverse perineal muscle and the external anal sphincter anal triangle - penetrated by the anus, external anal sphincter muscle (voluntarily to help prevent urination and defecation) pudendal nerve - innervates the transverse perineal muscle, external urethral sphincter, and external anal sphincter muscles o S2-S4 ventral rami

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o provides general somatic afferent fibers to the external genitalia transverse perineal muscle - origin: inferior pubic ramus and ischial pubic ramus o insertion: on the central tendon o action: supports pelvic viscera and anchors external genitalia external anal sphincter - origin and insertion: encircles the anus and attaches to the central tendon o action: voluntary constriction of the anus inhibiting defecation external female genitalia - Vulva, Mons pubis, Labia majora, Labia minora, Clitoris, Prepuce, Vestibule, mons pubis - fatty, rounded area overlying the pubic symphysis labia majora - the larger outer folds of the vulva. o extend posteriorly from the mons as fatty, elongated, hairy skin folds labia minora - thin, hairless folds medial to labia majora vestibule - recess between labia minora o contains external opening of the urethra and vagina clitoris - organ of sensitive erectile tissue anterior to the opening of the female urethra o corpus cavernosum and corpus spongiosum corpus cavernosa - closely aligned in the midline anterior to the vestibule and form part of the clitoral body or shaft o crura of the clitoris and attached to the ischial rami corpora spongiosum - form the two bulbs of the vestibule that flank the vagina and urethra deep to the labia and medial to the crura o forms the glans clitoris clitoral hood - tissue that partially or fully covers the clitoral glans bulbospongious muscle - originate on the central tendon and then run anteriorly to surround each bulb of the vestibule ishiocavernous muscle - originate on the ischial tuberosities and then run anteriorly to wrap around each crus paraurethral glands - found in the walls of the urethra on either side of the external urethral opening. they secrete mucus into the vestibule during sexual arousal. greater vestibular glands - found on either side of the vaginal orifice; open into the vestibule just medial to the labia minora; secrete mucous during sexual arousal external male genitalia - penis and scrotum shaft - hangs freely from the body glans of the penis - enlarged portion at the distal end of the body prepuce - foreskin; loose casing that covers the glans penis; removed by circumcision corpus spongiosum - contains the spongy urethra and keeps it open during ejaculation bulb of penis - enlarged proximal end of the corpus spongiosa glans penis - the conical mass of erectile tissue that forms the head of the penis

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crura of the penis - portions of the corpora cavernosa that flare laterally and attach to the ischial rami bulbospongious muscle in males - originates form the central tendon and the bulb of the penis to attach more distally on the corpus spongiosum o helps to empty the urethra after urination Ishiocavernous muscles in male - run from the ischial tuberosities onto the crura of the penis Homologous - share common embryonic origin o chart pg 41` blood supply to the perineum - internal pudendal artery internal pudendal artery - drains blood from the perineum into the internal iliac vein internal and external iliac vein - form to join the common iliac vein parasympathetic innervation of the perineum - produces the erection of external genitalia o originates from the gray matter of sacral spinal segments S2-S4 sympathetic innervation of the perineum - cause ejaculation and remission of erection of the external genitalia o originates in lateral horns of spinal segments T10-L2 and synapse in one of the pre vertebral ganglia...