Reproductive - Pelvic Girdle

Question 1

the four bones of the bony pelvis/ pelvic girdle

Answer 1

sacrum, coccyx, right and left hip bones

1. sacrum = 5 fused vertebral bodies, come together at distal end of vertebral column
2. coccyx = 3-5 fused bones, distal end of sacrum
3. right pelvic bones
4. left pelvic bones

Question 2

functions of the bony pelvis

Answer 2

transmits body’s weight form vertebral column to hip bones to femurs

contains, protects and supports pelvic organs - bladder, rectum, anal canal, and reproductive tracts

provides attachment for lower limbs and trunk

anchors roots of external genitalia

Question 3

name the four joints of the pelvic girdle

Answer 3

1. pelvic symphysis = softens during pregnancy
2. sacroiliac joint
3. lumbosacral joint = between L5 and sacrum
4. sacrococcygeal joint

joints and ligaments soften during pregnancy, pelvic movements increase

Question 4

describe the pubic symphysis

Answer 4

secondary cartilaginous joint where left and right pubic bones articulate

softens during pregnancy and can cause extreme pain

Question 5

function of the sacroiliac joint?

Answer 5

wight-bearing functiogn - transfers weight from sacrum to hip bones to femur

Question 6

name the three ligaments of the pelvic girdle and their functions

Answer 6

sacrospinous, sacrotuberous, sacroiliac ligaments

1. sacroiliac = between sacrum and ilium, weight-bearing
2. sacrotuberous = between sacrum and ischial tuberosity
3. sacrospinous = between (distal end of) sacrum and ischial spine

sacrospinous and sacrotuberous ligaments turn the greater and lesser sciatic notches into greater and lesser sciatic foramens

Question 7

name the 3 pelvic foramina

Answer 7

obturator foramen, greater sciatic and lesser sciatic foramens

obturator foramen = covered by obturator membrane, leaves a small canal through which the pelvic neurovascular bundle can run through

greater sciatic foramen = structures run from pelvic cavity to lower limb

lesser sciatic foramen = structures from pelvic cavity to perineum & gluteal region

Question 8

what is the greater sciatic foramen? function?

Answer 8

formed by sacrospinous and sacrotuberous ligaments

structures run from pelvic cavity to lower limb

Question 9

what is the lesser sciatic foramen? function?

Answer 9

formed by the sacrospinous and sacrotuberous ligaments

structures run from pelvic cavity into perineum and posterior gluteal region

Question 10

describe the obturator foramen

Answer 10

covered by the obturator membrane - reduces the size of the foramen through which the pelvic neurovascular bundle passes through

Question 11

describe the three pubic bones

Answer 11

ilium, ischium, pubis

ilium is superior, ischium is posterior, pubis is anterior

fuse together between 16-18 yrs and form the rounded acetabulum

Question 12

what is the rounded acetabulum?

Answer 12

formed by the fusion of the ilium, ischium and pubis

where the head of the femur sits

Question 13

name the 2 muscles of the pelvic wall

Answer 13

piriformis (superior)
obturator internus (inferior)

Question 14

describe the piriformis muscle

Answer 14

runs from sacrum, through greater sciatic foramen, inserts on femur - superior muscle

Question 15

describe the obturator internus

Answer 15

lines obturator membrane on internal surface of pelvis - takes a 90 degree turn, passes through lesser sciatic foramen and attaches to femur

covered by obturator internus fascia which thickens as a tendinous arch that levator ani muscle of pelvic floor arises from

Question 16

describe the orientation of the pelvic cavity

Answer 16

anterior superior iliac spines lie in the same vertical plane as pubic symphysis

Question 17

what is the pelvic inlet?

Answer 17

ring of bone where the infant’s head passes through during childbirth - enters birth canal and exits vaginal cavity

ring of bone divides pelvic inlet into greater/false pelvis and lesser/true pelvis

Question 18

describe the anterior, posterior and lateral bony landmarks that demarcate the pubic inlet

Answer 18

anterior = pubic symphysis

posterior = margin of the ala of the sacrum & sacral promontory

lateral = pubic crest, pectin pubis and arcuate line of the ilium

Question 19

describe the greater/false pelvis

Answer 19

above the pelvic inlet - demarcated by:
anterior = abdominal wall, rectus abdominus muscle
posterior = lower L1-5
laterally = flared iliac fossae

can be considered part of the abdominal cavity ss it contains part of the lower GI tract

guides foetus into the true pelvis during labour

Question 20

describe the lesser/true pelvis

Answer 20

below pelvic inlet, above pelvis outlet

contains pelvic organs, includes the true pelvic cavity and deep parts of the perineum - separated by the pelvic floor

Question 21

what is the perineum?

Answer 21

area enclosed by the pelvic outlet, below the pelvic floor

Question 22

what is the pelvic outlet?

Answer 22

diamond shaped, bony area enclosed by the pelvic floor muscles

terminal parts of the urinary & GI tracts and vagina pass through

Question 23

describe the anterior, posterior and lateral bony landmarks that demarcate the pubic inlet

Answer 23

anterior = bony pubic arch - combined left and right ischiopubic ramus

posterior = sacrotuberous ligament, sacrum and coccyx

lateral = flared ischial tuberosity (the bone we sit on)

pelvic floor muscles enclose the pelvic outlet, has the perineum below

Question 24

what is the pelvic floor?

Answer 24

bowl-shaped, consists of muscles that form the inferior boundary of the pelvic cavity, superior boundary of the perineum

incomplete anteriorly to allow passage of urethra, vagina and rectum

Question 25

function of the pelvic floor?

Answer 25

supports pelvic organs and prevents prolapse

maintains continence, and closure of the vagina & rectum

Question 26

name the two muscles of the pelvic floor

Answer 26

(ischio)coccygeus
levator ani

Question 27

describe the (ischio)coccygeus muscle

Answer 27

posterior muscle of the pelvic floor, one on the left and right

runs from ischial spine to coccyx & distal sacrum

Question 28

describe the levator ani muscle

Answer 28

consists of multiple different muscles with one on the left and right

arises from tendinous arch of obturator internus fascia - muscle fibres converge and fuse at ani-coccygeal ligament to strength the pelvic floor, prevent prolapse

Question 29

sex differences between male and female pelvic girdles

Answer 29

subpubic angle for males is 50-60; females is 80-90

pelvic inlet for males is heart shaped; females is oval shaped

lesser/true pelvis for males is narrow and deep; females is wide and shallow

males have a deep greater/false pelvis; females have it shallower

pelvis itself is thick and heavy for males thin and light for females

• anatomical differences are important in forensics, identify age and gender of a body