Female Reproductive Anatomy Flashcards
What is the pelvic girdle?
Bony pelvis formed by paired hip bones and sacrum; united by sacroiliac joints, pubic symphysis and strong ligaments
What is the difference between the false and true pelvis?
The pelvic inlet/brim divides the pelvis into 2 main regions:
- False/greater pelvis ABOVE (abdominal region)
- True/lesser pelvis BELOW (pelvic region) - obstetric sig. as it provides bony framework for birth canal
What is the pelvic floor?
Bowl shaped sheet of muscles (mainly LEVATOR ANI) that supports pelvic organs
Where is the perineum and how can be it divided?
Diamond-shaped region below pelvic floor between the thighs between vagina/penis and anus and it can be divided into:
- Urogenital triangle: pubic symphysis and ischial tuberosities
- Anal triangle: ischial tuberosities and coccyx
What is the orientation of the pelvis?
When standing upright, the plane of the pelvic inlet lies 60 degrees to the horizontal anterosuperiorly so the urogenital triangle faces inferiorly (thus bearing most of the bodies weight) and anal triangle faces posteroinferiorly
What are the areas of the true pelvis the baby needs to navigate in childbirth from widest to narrowest?
Transverse diameter Intertuberous distance Diagonal conjugate Interspinous distance True conjugate
What is the difference between the male and female pelvis?
Female gynaecoid pelvis:
- Wider inlet/outlet
- Thinner boned
- Cylindrical cavity
- Broad semi-circular pubic arch
Male android pelvis:
- Heart-shaped pelvic inlet
- Narrower inlet/outlet
- Thicker boned
- Acute angled thinner pubic arch
What are the muscles of the pelvic floor?
Levator ani group (illiococcygeus, pubococcygeus + puborectalis) and ischiococcygeus (S4 pudendal innervation) that attach via the tendinous arch (thickening of fascia) over obturator internus
What muscles make up the walls of the pelvic cavity?
Lateral hip rotators:
Obturator internus
Piriformis
How must structures like nerves/vessels move from the pelvic cavity, through the pelvic floor to the perineum?
Greater and lesser sciatic foramen
What is tonic baseline activity?
That muscle tonicity needed to support and pull the pelvic organs up and forwards
What are the roles of the pelvic floor muscles?
- Support pelvic organs
- Prevent prolapse
- Maintain continence (esp. puborectalis which helps maintain anorectal angle)
What are the weak spots of the perineal membrane?
Openings in the urogenital hiatus:
- Urethra opening
- Anal aperture
- Vagina (in females)
What is the perineal body? What are its functions?
A tough mass of fibres that lie between the external genitalia and anal canal providing a point of union between pelvic floor muscles and perineal membrane functioning in:
- Pelvic floor integrity
- Support of posterior vaginal wall in females
- Attachment point for anal sphincters
What are the contents of the perineum in females?
Crura of clitoris
Bulb of vestibule
Labia (majora and minora)
Greater vestibular glands
Internal pudendal vessels/branches
Pudendal n. and branches
Perineal membrane
What are the contents of the perineum in males?
Crura and bulb of penis
Urethra
Scrotum and testes
Bulbourethral glands
Internal pudendal vessels/branches
Pudendal n. and branches
Perineal membrane
What are the different pouches in the perineal region?
Urogenital triangle:
- Deep perineal pouch above perineal membrane and between that and the pelvic floor
- Superficial perineal pouch below perineal membrane
Anal triangle: ischioanal fossae wedge-shaped fat-filled regions
What is contained within the perineal pouches?
Voluntary muscles (pudendal n. innervated S2-4) Bulbourethral glands in males
What is the clinical significance of bulbourethral glands?
They can become infected or develop stones producing intense pain exacerbated by defecation/DRE
What is the clinical significance of the greater vestibular (Bartholin’s) gland?
The gland drains into the vestibule at 5 and 7 o’ clock positions relative to vagina opening and the glands may become inflamed, infected and form cysts/abscesses at these positions
What structures contribute to forming the clitoris?
Bulb of vestibule and paired corpora cavernosa (forms crura of clitoris) - erectile bodies covered by muscles called the bulbospongiosus and ischiocavernosus respectively
What muscles help stabilise the perineal body?
Deep and superficial transverse perineal muscles
What homology exists between the male and female external genitalia?
Clitoris = penis (both have paired corpora cavernosa and sensitive glands with S2-4 innervation)
Greater vestibular = bulbourethral
Bulb of vestibule = corpus spongiosum of penis
What is a episiotomy?
Most often mediolateral surgical incision of the perineum to widen the vaginal opening and facilitate delivery - not routinely indicated now unless equipment needs to get in to aid the delivery
What layers does a episiotomy cut through?
Posterior vagina wall Transverse perineal muscles Bulbospongiosus Perineal membrane Levator ani Subcutaneous tissue Perineal skin
What is the female reproductive tract made up of?
Closed packed organs inc. vagina, cervix, uterus, fallopian tubes and ovaries mainly within true pelvis with peritoneum draped over them - why cancer and other pathologies can spread to adjacent structures easily (ureters are also closely related to lateral cervix/uterus)
What are the peritoneal pouches?
Vesicouterine (between bladder and uterus)
Rectouterine (between rectum and uterus) - most gravity dependent in females so intraperitoneal fluid/blood/pus can accumulate
What is the vagina?
Distensible fibromuscular tube that lies between bladder/urethra and rectum connecting the vestibule to the external os of the cervix running posterosuperiorly - innervated by pelvic sphlanchnic and pudendal n. (S2-4)
What structures can prolapse via the vagina and its walls?
Bladder (cystocele)
Rectum (rectocoele)
Uterus
What is the cervix?
Lowest part of uterus connecting the uterine cavity and vagina (site of TZ) projecting into vaginal vault forming a continuous recess called the vaginal fornix (posterior is deepest adjacent to rectouterine pouch and foreign bodies can get stuck here) - can be viewed with the help of a speculum
What is the uterus?
Thick walled pear-shaped hollow muscular organ with a cavity lined by endometrium and linked to uterine tubes; made up of:
- Myometrium (thick SM layer) - benign SM tumours (fibroids) may form here
- Perimetrium (outer serosal layer)
Size/position assessed by bimanual palpation and cavity can be viewed via a hysteroscopy
What is the normal alignment of the uterus?
Angle of version between vagina and cervix = ANTEVERSION
Angle of flexion between cervix and uterus = ANTEFLEXION
Others exist but can be associated with pathology e.g. endometriosis in retroversion and retroflexion positions
What are uterine tubes?
Paired fallopian tubes connected to uterine cavity and open into peritoneal cavity with fimbriae from the infundibulum lying over the ovary ready to receive the ovum at ovulation - shape and patency of uterine cavity/tubes demonstrated with hysterosalpingogram (HSG)
Where does fertilisation and implantation normally occur?
Fertilisation = ampulla of uterine tubes
Implantation = uterine cavity
What clinical problems can occur in the uterine tubes?
- Ectopic pregnancies which can rupture leading to haemoperitoneum
- Route of infection spread from vagina causing PID ranging from salpingitis to tubal abscesses sometimes involving the ovary (tuboovarian abscess)
What is Pelvic Inflammatory Disease (PID) a risk factor for?
Ectopic pregnancy
Sub-fertility
How do ovaries develop positionally?
Structures that develop from the intermediate mesoderm on the posterior abdominal wall (~L2) and descend to adult position taking their blood supply and lymphatics with them ending up sitting close to lateral pelvic wall suspended within broad ligament close to obturator n. covered in peritoneum which is continuous with its surface epithelium germinal layer
Where does ovulation take place?
Through epithelial germinal layer into peritoneal cavity
What is the lymph drainage of the testicles and ovaries?
Para-aortic lymph nodes
What ligaments exist in the female reproductive tract?
- Broad ligament: large double layered fold of peritoneum surrounding and supporting uterus, uterine tubes and ovaries
- Suspensory ligament of ovary: suspends ovary off posterior aspect of broad ligament and contains vessels/lymphatics
- Round ligament of ovary: remnant of gubernaculum that connects ovary to uterus
- Round ligament of uterus: remnant of gubernaculum that runs from uterus to labia majora via inguinal canal (cancer spread to inguinal nodes)
What are the 3 different regions of the broad ligament?
- Mesometrium: related to uterus
- Mesosalpinx: related to uterine tubes
- Mesovarian: related to ovaries
What surgical procedures can be performed here?
Pfannenstiel/suprapubic incision to access uterus and pelvic organs:
- Total abdominal hysterectomy (TAH) OR vaginal hysterectomy (through vagina) to remove uterus and cervix
- Subtotal hysterectomy where cervix is preserved
- Radical hysterectomy to remove uterus, cervix AND associated supporting tissues/lymphatics
- Bilateral sapingo-oophorectomy (BSO) to remove both uterine tubes and ovaries
What are the different kinds of pelvic fascia that exist?
All below peritoneum:
- Visceral: covers organs
- Parietal: covers muscles and walls
- Endopelvic: fills spaces with loose and fatty connective tissue that can be dense/fibrous in some areas forming distinct supportive ligaments
What supporting ligaments does the endopelvic fascia form and what are their functions?
- Parametrial ligaments inc. cardinal (transverse cervical), sacrocervical (uterosacral) and pubocervical support the uterus
- Paracolpium is around the vagina supporting it and connecting to the tendinous arch
What is the blood supply to the female reproductive tract?
Aorta gives rise to ovarian artery and internal illiac artery branches into internal pudendal artery that supply the perineum and variable branching pattern of vessels supplying other organs but obviously named e.g. uterine, vaginal and vesical arteries
Rich anastomoses between organs allows for large increase in flow demanded during pregnancy
What passes close to the uterine artery and why is this clinically relevant?
Ureter passes close to and below the uterine artery lateral to the cervix so the ureter is at risk of damage/irritation during surgical procedures where this artery needs to be manipulated e.g. hysterectomy where it has to be ligated
What is the lymph drainage of this region?
Para-aortic nodes: ovaries, uterine tubes and fundus of uterus
Internal/external illiac nodes (and sacral): body of uterus, cervix and proximal vagina
Superficial/deep inguinal nodes (and external illiac): distal vagina and external genitalia
Why can parts of the uterus drain to palpable superficial inguinal nodes?
Round ligament of uterus
What is the nerve supply of this region? How would you anaesthetize this region?
Above pelvic pain line covered in peritoneum:
- Visceral sympathetics (lower thoracic/upper lumbar levels ~T10-L1/2): uterus, uterine tubes, bladder roof and upper rectum so anaesthetize by spinal epidural or combined (CSE/CES)
Below pelvic pain line not covered in peritoneum:
- Visceral parasympathetics (pelvic sphlanchnic n. S2-4): cervix and proximal vagina so anaesthetize by caudal epidural (not done often in obstetrics due to difficulty)
- Somatic (pudendal n. S2-4): perineum, distal vagina and anal canal so anaesthetize by pudendal nerve block
When might you use a pudendal nerve block?
To repair a episiotomy incision
What is the pudendal nerve? What are its main branches?
It is the main somatic nerve (S2-4) coming off of the sacral plexus to the perineal region with branches supplying the external genitalia, perineal skin, perineal pouch muscles and urinary/anal sphincters
What is the route of the pudendal nerve?
Passes out of pelvic cavity via greater sciatic foramen and into perineum below the pelvic floor going through the lesser sciatic foramen - runs close to ischial spines (where you would anaesthetize it) and sacrospinous ligament and then branches off
