anatomy exam 5

naurovasculature of anterior abdominal wall

continuous with thorax

superior and inferior epigastric arteries anastamose in rectus abdominis

L1 dermatome- iliohypogastric and ilioinguinal nerves

linea alba largely devoid of neurovascular structures, but less blood supply and incision perpendicular tension lines (hard for incision to heal and close bc a lot of tension)

anterior abdominal wall embryology

gubernaculum and female anatomy: cord like structure going from ovaries, through anterior abdominal wall and into labia major

• in adults: upper → ovarian ligament; lower → round ligament of uterus

gubernaculum and male anatomy: cord like structure going from testis through anterior abdominal wall and into fold which will become scrotum

• gubernaculum shortens as testis descends (processus vaginalis forms and testis drops into it) to form inguinal canal and tunica vaginalis

dartos fascia (continuation of scarpa’s fascia into scrotum), external spermatic fascia (continuation of external oblique aponeurosis), cremaster muscle and fascia (continuation of internal oblique muscle), internal spermatic fascia (continuation of transversalis fascia), tunica vaginalis (continuation of parietal peritoneum)

hernias

points of weakness: femoral ring, medial inguinal fossa/hesselbach’s triangle, deep inguinal ring

types of inguinal hernias: indirect (lateral inguinal fossa), direct (hesselbach’s triangle)

in males: superficial and deep inguinal rings will not be aligned (keeps inguinal canal closed)

pelvis

pelvic inlet separates greater (false) pelvis from lesser (true) pelvis

female: greater = shallow; lesser = wider; pelvic inlet = ovular; subpubic angle > 80 degrees; obturator foramen = ovular

ligaments: pubic symphysis, sacrospinous ligament, sacrotuberous ligament

pelvic diaphragm: coccygeus muscle and pelvic diaphragm, separates pelvis from perineum

puborectalis: contraction allows poop to be held in

perineum

inferior to pelvic diaphragm

male triangles: draw a line between ischial tuberiosities

• anterior is urogenital triangle (genital hiatus)

• in between is perineal body (provides structure of the perineum)

• posterior is anal triangle (rectum)

female triangles: draw a line between ischial tuberiosities

• anterior is urogenital triangle (vagina)

• in between is perineal body

• posterior is anal triangle (rectum)

superficial pouch borders: perineal membrane, perineal fascia, ischiopubic rami

deep pouch borders: inferior fascia of pelvic diaphragm, perineal membrane, obturator fascia

anal triangle and ischioanal fossa- large amounts of fat to allow for expansion of anus

pudendal canal: pudendal nerve and internal pudendal artery and vein (supply perineum)

• nerve exits via greater sciatic perineum, controls external urethral and anal sphincters

internal anal sphincter: autonomic control (smooth muscle)

external anal sphincter: 3 layers of striated voluntary muscle

hemorrhoids

internal hemorrhoids (superior rectal vein, inferior mesenteric vein), above pectinate line, autonomic nerves, less painful

external hemorrhoids (inferiro rectal vein, inferior vena cava) below pectinate line, somatic nerves, more painful

pelvic urinary system

function: carry, expel, store urine

components: ureters, bladder, urethra

• bladder: trigone (lines from urethra opening to uretal openings), made of transitional epithelium so bladder can expand

• male urethra: preprostatic, prostatic, membranous, spongy

micturition: detrusor relaxes for bladder to fill with urine → stretch receptors fire → parasympathetic neurons fire → smooth muscle contracts, internal sphincter passively opens, external sphincter relaxes → urination

male repro system

testis- pick up layers as they descend into scrotum

epididymis- head, body, tail (becomes vas deferens)

spermatic cord contents- vas deferens, testicular artery, pempinform plexus of veins, genitofemoral nerve

seminal vesicles- secretes thick alkaline fluid

prostate gland- close off opening of bladder into urethra, secrete acidic prostatic fluid

bulbourethral glands- secrete mucus fluid

penis- corpus cavernosa, corpus spongiosum

erection and ejactulation

erection- parasympathetic- closes arteriovenous anastomoses by compressing emissary vein, increases blood flow into cavernous sinus by relaxing smooth muscle

somatic innervation- contracts bulbospongiusus and ischiocavernous muscles to compress veins of corpora cavernosa

ejaculation- sympathetic- emission deposits fluid/semen, ejaculation expels semen

pudendal nerve branches

inferior rectal- external anal sphincter

perineal nerve- external urethral sphincter, bulbospongiosus, ischiocavernosus

posterior scrotal nerves- cutaneous innervation of scrotum

dorsal nerve of penis- cutaneous innervation of penis

female repro

uterus- myometrium causes uterine contraction during labor

uterine tubes- isthmus, ampulla, infindibulum, fimbria

labia majora- adipose tissue, pubic hair, lateral

female erection and ejaculation

erection caused by engorgement of blood following stimulation

female ejaculation not well understood

sympathetics to pelvic organs

preganglionic cell bodies: T10-L2

preganglionic axons: lesser splanchnic, least splanchnic, lumbar splanchnic, sacral splanchnic

postganglionic cell bodies: ganglia surrounding and inferior to abdominal aorta (superior hypogastric plexus, hypogastric nerve, inferior hypogastric plexus)

postganglionic axons: following arteries or direct branches from inferior hypogastric plexus

uterus: T10-L1

parasympathetics to pelvic organs

preganglionic cell bodies: S3-S4

preganglionic axons: pelvic splanchnic nerves from S3-S4 → direct to organ (or to minute pelvic ganglia first)

post ganglionic cell bodies: in organ walls or minute ganglia in inferior hypogastric plexus

postganglionic axons: in organ walls or passing from minute ganglia in inferior hypogastric plexus to organ

visceral sensory from pelvic organs

organs inferior to pelvic pain line and unconscious reflex sensation (such as distension) follow parasympathetics back to S3-S4 → intraspinal reflex → contraction of muscles (ex: when bladder is full)

some back to S3-S4

some back to levels of sympathetic innervation

pain during childbirth

contraction of uterus (T10-L1)- with sympathetics

distension of cervix (S3-S4)- with parasympathetics

pain of delivery (pudendal nerve S2-S4)- somatic pain

urination

visceral pain from bladder stretching (following parasympathetics to S3-S4)

bladder contracts (intraspinal reflex), parasympathetics to detrusor via pelvic splanchnic nerve

IUS relaxes (inhibition of sympathetics)

external urethral sphincter relaxes (somatic)

development of gonads

develop from mesothelium, underlying mesenchyme, primordial germ cells (earliest undifferientiated sex cells)

gonads develop at week 5 from thickened mesodermal epithelium of the mesonephros at the gonadal ridge

during this indifferent stage, the embryo has the potential to develop into either male or female → development of mesonephric and paramesonephric ducts

SRY gene produces testis-determining factor → development of gonadal cords into seminiferous cords → sertoli cells produce anti mullerian hormone → paramesonephric ducts disintegrate

no TDF present → cortex develops, medulla regresses → epithelial cortex cells become follicular cells to surround ovarian follicle → ovaries produce anti mullerian hormone at lower levels (develop follicles prior to ovulation)

ovaries descend but get interrupted by developing paramesonephric ducts

development of genital ducts

mesonephric duct forms: ureter, seminal gland, prostatic utricle, inguinal canal, eipdidymis, efferent ductules, ductus deferens, ejaculatory ducts

paramesonephric duct forms: uterine tube, uterus, superior vagina

• abnormalities: genesis, lateral fusion defects, vertical fusion defects

development of external genitalia

structures that develop from the same embryonic precursors are developmentally homologous (ex: labia majora and scrotum are homologous)

differentiating factor is presence of DHT → larger erectile bodies and fusion of scrotum

hypospadia: caused by failure of urethral folds to close all the way from the scrotum to the glans

repro development clinical correlates

when an otherwise femal embryo is exposed to DHT in first trimester → large clitoris containing urethra, urethral folds merge and may close off vagina

• caused by: maternal suprarenal gland tumor, congenital adrenal hyperplasia

5 alpha reductase syndrome: individuals have XY but deficiency of production of DHT (external genitalia range in appearance, at puberty surge of testosterone may cause masculinization including descent of testes)

turner’s syndrome- only viable monosomy (45XO)- external female genitalia, dysgenesis of gonads, webbed neck

klinefelter’s syndrome- 47XXY, gynecomastia, hypogonadism, infertility