Anatomy of the pelvis

Question 1

What 4 bones make up the pelvis?

Answer 1

Sacrum

Ilium

Ischium

Pubis

Question 2

Where are the 2 coxal hip bones joined?

Answer 2

Pubic symphysis anteriorly

SI joint posteriorly

Question 3

What 3 bones unite to form the acetabulum?

Answer 3

Ilium

Ischium

Pubis

Question 4

What important structures/landmarks does the ilium contain?

Answer 4

Ala of ilium

4 iliac spines: posterior superior and inferior
Anterior superior and inferior

Greater sciatic notch

Question 5

What important structures/landmarks does the ischium contain?

Answer 5

The ischial spines

Ischial tuberosity

Lesser sciatic notch

Question 6

What are the components of the pubis?

Answer 6

Pubic symphysis

Pubic tubercle

Pubic crest

Question 7

What 2 structures of the anterior pelvis are on the same plane?

Answer 7

anterior superior iliac spine is on the same plane as the pubic tubercle

Question 8

What is the difference between the greater and lesser pelvis?

Answer 8

Greater pelvis is above pelvic inlet and lesser pelvis is inside pelvic inlet

Question 9

What is another name for the greater pelvis?

Answer 9

False pelvis and the opposite is true (pun intended)

Question 10

What are the boundaries of the greater pelvis?

Answer 10

Posteriorly the lumbar spine

Posterolaterally the ala of the illium

The abdominal wall anteriorly

Question 11

What are the boundaries of the pelvic inlet?

Answer 11

Sacral promontory + sacral alae posteriorly

Arcuate + pectineal lines laterally

Upper margin of pubic symphysis anteriorly

Question 12

What are the boundaries of the pelvic outlet?

Answer 12

Tip of coccyx posteriorly

Sacrotuberous ligament posterolaterally

Ischial tuberosity laterally

Ischiopubic ramus anterolaterally

Lower margin of pubic symphysis anteriorly

Question 13

What are the boundaries of the pelvic cavity?

Answer 13

Sacrum + Coccyx posteriorly

Ilium + ischium laterally

Body of pubic bone, pubic rami, and pubic symphysis anteriorly

Question 14

What is in the pelvic cavity?

Answer 14

Pelvic viscera

Nerves

Blood vessels

Muscles

Question 15

What is the most common pelvic shape in males?

Answer 15

Android

Question 16

What is the most common pelvic shape in females?

Answer 16

Gynecoid

Question 17

What is a pelvic shape sometimes seen in males and black females?

Answer 17

Anthropoid

Question 18

What is the transverse diameter of the pelvic inlet?

Answer 18

11cm

Question 19

What is the transverse diameter of the pelvic outlet?

Answer 19

13cm

Question 20

What is the anteroposterior diameter of the pelvic inlet?

Answer 20

13 cm

Question 21

What is the anteroposterior diameter of the pelvic outlet?

Answer 21

11cm

Question 22

What is the oblique diameter of both the inlet and outlet?

Answer 22

12cm

Question 23

What is the interspinous distance?

Answer 23

10cm

Question 24

Do the pelvic inlet and outlet lie in a completely horizontal plane in anatomical position?

Answer 24

No the inlet is oblique angle of 55 degrees with horizontal plane whereas outlet is at an angle of 45 degrees with horizontal plane

Question 25

How is the female pelvis different to the male pelvis?

Answer 25

Outlet is wider Inlet is open and circular Ischial spines are more distant Wider greater sciatic notch Longer pubis and shorter ischium Sacrum is flatter and shorter Broader hips and tailbone Pubic arch/ subpubic angle is greater than 90 degrees lighter bones

Question 26

Where does the sacrospinous ligament attach?

Answer 26

laterally attached to the ischial spine Medially attached to the sacrum and coccyx

Question 27

Where does the sacrotuberous ligament attach?

Answer 27

Ischial tuberosity inferiorly Posterior superior iliac spine, lower part of posterior surface of sacrum and upper part of coccyx

Question 28

What landmarks constitute the surfaces of the pelvic cavity?

Answer 28

Anterior wall Pelvic floor: levator ani and coccygeus Posterior wall is composed of pelvic surface of the sacrum and coccyx Lateral walls composed of pelvic surface of ilium and obturator internis and its fascia

Question 29

Where does the piriformis muscle originate?

Answer 29

On the sacrotuberous ligament The gluteal surface of the ilium The sacrum at S2 - S4

Question 30

Where does the piriformis insert?

Answer 30

Greater trochanter of the femur

Question 31

What spinal nerves innervate the piriformis?

Answer 31

The anterior rami of S1 - S2

Question 32

What does the piriformis do?

Answer 32

Rotates femur laterally and holds femur head in acetabulum

Question 33

Where does the obturator internis originate?

Answer 33

Obturator membrane and pelvic surface of the ilium and ischium

Question 34

Where does the obturator internis insert?

Answer 34

Greater trochanter of the femur

Question 35

What does the obturator internis do?

Answer 35

Laterally rotates femur and keeps head of femur in acetabulum

Question 36

Where does obturator internus get its nerve supply?

Answer 36

Anterior rami of L5 S1 and S2

Question 37

What are the main muscles of the pelvic floor?

Answer 37

Levator ani coccygeus

Question 38

What are the levator ani muscles?

Answer 38

Pubococcygeus (consists of puborectalis and puboprostaticus/pubovaginalis) Iliococcygeus Coccygeus

Question 39

Where does the iliococcygeus originate and insert?

Answer 39

Origin: tendinous arch of obturator fascia and iscial spine Inserts: anococcygeal raphe and coccyx

Question 40

Where does the coccygeus originate?

Answer 40

Ischial spine

Question 41

Where does the coccygeus insert?

Answer 41

lower sacrum and coccyx

Question 42

Where does nerve supply of coccygeus come from?

Answer 42

S4 and S5 spinal nerves

Question 43

Where does levator ani get its nerve supply?

Answer 43

S4 branches Inferior anal nerve Coccygeal plexus

Question 44

What is the closest muscle to the center around anus ?

Answer 44

Puborectalis

Question 45

What is the role of the pelvic floor?

Answer 45

Supports viscera of pelvis Equalizes intraabdominal pressure during defacation and parturition

Question 46

Which muscle is most often torn during childbirth?

Answer 46

Pubococcygeus

Question 47

What does puborectalis do?

Answer 47

Forms sling around anus that helps with fecal continence

Question 48

What is a possible consequence of injury to pelvic floor muscles?

Answer 48

Prolapse in uterus or rectum Neck of bladder can be moved resulting in urinary incontinence.

Question 49

Where is the uterovesical pouch?

Answer 49

Anterior to the uterus Posterior to the bladder

Question 50

Where is the rectouterine pouch?

Answer 50

Between rectum and uterus

Question 51

What is another name for the rectoterine pouch?

Answer 51

Pouch of douglas

Question 52

What does the rectouterine pouch cover?

Answer 52

Anterior part of middle third of the rectum and upper rectum The uterus anteriorly The posterior fornix of the vagina inferiorly

Question 53

Describe the rectovesical pouch and who has it?

Answer 53

The male peritoneal pouch covers the base of the bladder as well as the superior portion of the bladder it also covers the anterior part of the middle third of the rectum and continues to cover it superiorly until it becomes continuous with the posterior abdominal wall

Question 54

What is the clinical significance of the abdominal pouches?

Answer 54

Any free fluid accumulates in those pouches. For example, pus from abscesses or blood from rupture of blood vessels.

Question 55

What are the paravesical fossae?

Answer 55

Some peritoneum is reflected laterally into lateral pelvic wall from superior bladder wall and is continuous with the pelvic wall.

Question 56

What is the broad ligament?

Answer 56

Membrane is folded over fallopian tubes in such a way that underneath them the membrane meets itself in the form of a double membrane. As a result this tissue connects the ovary to the uterus and is called the broad ligament. It also covers the ovary

Question 57

What is the difference between male and female peritoneal cavity?

Answer 57

In males the lower extent the peritoneal cavity is closed. In females inferiorly the peritoneal communicates with exterior atmosphere via the uterine tube. Any infection in vagina or uterine tube could spread into the peritoneam called peritonitis.