Gynecology (Tony's) Flashcards
(406 cards)
Sex determination
Chromosomal sex determined at conception (XX, XY)
Sex differentiation
Development of male or female urogenital system which involves sex and autosome chromosome genes
Genotypic/primary sex differentiation - development of gonads
Phenotypic/seconday sex differentiation is development of the urogenital system
Male sex differentiation
Y chromosome contains SRY (sex determining region) gene, which encodes TDF (testis-determining factor)
TDF initiates cascade of downstream events to develop male urogenital system (mullerian inhibiting substance (MIS) + testosterone to develop male urogenital system)
Female sex differentiation
Default pathway is female (absence of SRY gene)
Development of the ovaries
- Gonadal ridges in the mesoderm
- Primordial germ cells develop in endoderm of yolk sac and migrate via dorsal mesentary to invade the genital ridges
- Celoemic epithelium gives rise to primitive sex chords, which penetrate the underlying mesenchyme
- In male develop into testis (primitive sex chords develop to form seminiferous tubules and tunica albuginea thickens)
- In female develop into ovaries (primitive sex chords develop to form medulla of ovary and tunica albuginea disappears) and surface epithlium gives rise to secondary sex cords (become follicular cells)
Descent of ovaries location and support
Ovaries move inferiorly and settle just below the rim of the true pelvis.
The superior (cranial) genital ligament forms the suspensory ligament of ovary.
The inferior (caudal) genital ligament (aka gubernaculum) forms the ovarian ligament and round ligament of uterus
Genital duct development
- Indifferent stage - mesonephron (Wolfian) duct develops if male and paramesonephric (Muellerian) duct develops if female
- Sex differentiation of genital duct
MIS and testosterone presence or absence
Role of testosterone in the differentiation of the genital duct
Testosterone stimulates development of mesonephric duct and stimulates development of male external genitalia
Absence results in disintegration of mesonephric duct and development of female external genitalia (labia majora, labia, minora, clitoris and lower 2/3 vagina)
Role of MIS in sex differentiation of genital duct
MIS - inhibits development and stimulates disintegration of paramesonephric duct which develops into uterine tube, uterus and superior part of vagina
Formation of uterus
Bilateral paramesonephric ducts fuse at the distal end to become uterus and superior part of vagina and septae eventually disappears
Formation of vagina
Dual origin where the superior part is derived from paramesonephric duct and the inferior part is derived from urogenital sinus
What are the components that make up the pelvic brim
- Sacral promontory
- Margin of sacral ala
- Arcuate line of ilium
- Pectineal line
- Pubic crest
What is the pelvic outlet
plane bounded by tip of coccyx posteriorly; sacrotuberous ligament posteriolaterally; ischial tuberosities laterally; ischiopubic rami and pubic symphysis anteriorly
What is the pelvic diaphragm and its components
Funnel shaped muscular floor composed of floor of lesser (true) pelvis and roof of perineum
Made by coccyges and levator ani (pubococcygeus, iliococcygeus) muscles
What is the pelvic brim
Divides the superior greater (false) pelvis and inferior lesser (true) pelvis
What are the conjugate measurements of the pelvis
Anatomical (true) conjugate
Obstetric conjugate
Diagonal conjugate
True conjugate
Distance from sacral promontory to superior aspect of pubic symphysis
Obstetric conjugate
distance from sacral promontory to most posterior aspect of pubic symphysis
Diagonal conjugate
distance from sacral promontory to inferior aspect of pubic symphysis
What is the transverse diameter of pelvic outlet
distance between ischial tuberosities (10-11cm)
What is interspinous diameter
distance between ischial spines
What penetrates the pelvic diaphragm
Urethra, vagina, rectum
What is the role of the medial fibers of levator ani (part of pubococcygeus)
Forms sling around rectum (puborectalis)
What is the role of the pelvic diaphragm
supports pelvic viscera, contribute to fecal / urinary continence