FEMALE PELVIC ANATOMY

Question 1

What forms the pelvic girdle

Answer 1

(bony pelvis) formed by paired hip bones & sacrum; united by sacroiliac joints, pubic symphysis & strong ligaments

Question 2

What does the pelvic inlet divide the regions into?

Answer 2

False (greater) pelvis lies above pelvic inlet (abdominal region of pelvic girdle)

True (lesser) pelvis lies below pelvic inlet – obstetric significance as provides bony framework for birth canal

Question 3

What is the pelvic floor formed by?

Answer 3

Pelvic floor formed by a bowl shaped sheet of muscles (mainly levator ani) that supports pelvic organs

Question 4

What is the perineum?

Answer 4

Perineum is region below pelvic floor between the thighs

Question 5

How is the perineum divided?

Answer 5

Perineum can be divided into urogenital & anal triangles using pubic symphysis, ischial tuberosities & coccyx

Question 6

Where is the Surgical / gynaecological perineum

Answer 6

Between vagina and anus

Question 7

Describe the orientation of the pelvis.

Answer 7

When standing upright, the plane of the pelvic inlet lies at ~60° to the horizontal (tilting anterosuperiorly)

Urogenital & anal triangles of the perineum are also angled relative to each other

Urogenital triangle faces inferiorly whilst anal triangle faces posteroinferiorly

Question 8

How is the female bony pelvis adapted for its function?

Answer 8

Female bony pelvis adapted for childbirth (gynaecoid features); tends to be wider, thinner boned, approximately cylindrical cavity with broad pubic arch

Question 9

How do structures pass from the pelvic cavity to the perineum?

Answer 9

To pass between pelvic cavity (above pelvic floor) to perineum (below pelvic floor), structures must traverse greater & lesser sciatic foramina

Question 10

What provides an attachment for the pelvic floor muscles?

Answer 10

Muscles, ligaments & bones form the walls of the pelvic cavity

Tendinous arch (thickening of fascia) over obturator internus provides attachment for the pelvic floor muscles (levator ani group + (ischio)coccygeus)

Question 11

What muscles make up the levator ani group?

Answer 11

Levator ani group made up of three muscles (similar actions)
Iliococcygeus
Pubococcygeus
Puborectalis

Question 12

What is the function of the pelvic floor muscles?

Answer 12

Tonic baseline activity – support & pull pelvic organs up & forwards

Question 13

Nerve supply of the pelvic floor muscles

Answer 13

Mainly S4 innervated (maybe some pudendal)

Question 14

What does the puborectalis muscle do?

Answer 14

Puborectalis helps maintain anorectal angle

Question 15

What is the key role of the pelvic floor muscles?

Answer 15

Pelvic floor muscles have key role in supporting pelvic organs, preventing prolapse & maintaining continence

Question 16

What is the function of the perineal membrane?

Answer 16

Openings allow passage through pelvic floor of some pelvic organs, but are potential points of weakness

Anal aperture for anal canal

Urogenital hiatus for urethra
(& vagina in females)

Question 17

What forms the covering of the urogenital hiatus?

Answer 17

Urogenital hiatus covered by perineal membrane – a tough fibrous sheet which has openings for urethra (& vagina) & provides attachment for external genitalia

Question 18

What is the perineal body?

Answer 18

Perineal body is a tough mass of fibres lying between external genitalia & anal canal

Question 19

What is the function of the perineal body?

Answer 19

Provides point of union between pelvic floor muscles & perineal membrane

Important for pelvic floor integrity

Supports posterior vaginal wall in females

Attachment point for anal sphincters

Question 20

What is the perineum?

Answer 20

Perineum is diamond shaped region below pelvic floor & between thighs; contains external genitalia & distal anal canal

Question 21

Contents of the perineum in both sexes

Answer 21

Internal pudendal vessels & branches
Pudendal nerve & branches
Perineal membrane

Question 22

Contents of the perineum in female anatomy

Answer 22

Crura of clitoris
Bulb of vestibule
Labia (majora & minora)
Greater vestibular glands

Question 23

Contents of the perineum in male anatomy

Answer 23

Crura & bulb of penis
Urethra
Scrotum & testes
Bulbourethral glands

Question 24

What fat filled region is contained in the urogential triagnle?

Answer 24

Anal triangle contains fat filled wedge shaped regions – ischioanal (ischiorectal) fossae

Deep to pelvic floor either side of anus/rectum with anterior extensions into urogenital triangle

Question 25

How is the perineum further divided into regions?

Answer 25

Urogenital triangle contains perineal pouches (deep & superficial)

Fascia bound regions that lie either above (deep) or below (superficial) the perineal membrane

Question 26

What can happen to bulbourethral glands that may cause pain? when may this pain be exacerbated?

Answer 26

Bulbourethral glands can become infected / develop stones – intense pain exacerbated by defecation / rectal exam

Question 27

Where does the deep perineal pouch sit?

Answer 27

Deep perineal pouch sits between pelvic floor & perineal membrane

Question 28

What is contained in the perineal pouches?

Answer 28

Contains voluntary muscles innervated by the pudendal nerve (S2-4) (see block 1)

In males it also contains bulbourethral glands (analogous to greater vestibular glands in females)

Crura of penis / clitoris attach to pubic arch & inferolateral parts of perineal membrane

Question 29

What are the components of the external genetalia

Answer 29

Female external genitalia (vulva) found in urogenital triangle – folds of tissue guarding the vagina & clitoris
Spongy expansile vascular tissue (vestibular bulb) with overlying muscles lies deep to the skin on either side of the vestibule

Greater vestibular (Bartholin’s) glands drain into vestibule at 5 & 7 o’clock positions relative to vaginal opening

Question 30

What layers does the mediolateral episiotomy cut through?

Answer 30

Posterior wall of vagina
Transverse perineal muscles
Bulbospongiosus
Perineal membrane
Levator ani
Perineal skin & subcutaneous tissue