3. Bony Pelvis and Pelvic Wall (Carter)

Question 1

What is the anatomical position for the innominate?

Answer 1

The position in which the ASIS and anterior pubis are in the same vertical plane.

Question 2

Wire adults more likely to develop pelvic fractures than children?

Answer 2

Because the pelvis is fused after puberty, but connected with cartilage before that.

Question 3

Identify the arrows.

Answer 3

Question 4

What are the four weak points for pelvic fractures?

Answer 4

Pubic rami.

Acetabulum.

Sacroiliac joints.

Iliac ala.

Question 5

Is the greater pelvis shallower in the female or the male?

Answer 5

It is shallower in the female.

Question 6

Is the true pelvis narrower and deeper in the male or female?

Answer 6

The true pelvis is narrow and deep in the male – shallow and wide in the female.

Question 7

Is the pelvic aperture wider in males or females?

Answer 7

The pelvic aperture is wider in females.

Question 8

How wide is the typical male subpubic angle?

How wide is the typical female subpubic angle?

Answer 8

The male subpubic angle is typically less 70°.

The female subpubic angle is typically greater than 90°

Question 9

How does the obturator foramina differ in the male and female?

Answer 9

The male obturator foramen is typically round.

The female obturator foramen is typically oval.

Question 10

Is the acetabulum larger in the male or the female?

Answer 10

The acetabulum is larger in the male.

Question 11

Is the greater sciatic notch larger in the male or the female?

Answer 11

The greater sciatic notch is larger – around 90° – in the female.

The greater sciatic notch is smaller – around 70° – in the male.

Question 12

What is the tendinous arch of the levator ani made of?

Answer 12

A thickening of the obturator internus fascia.

Question 13

What does the tendinous arch of the levator ani separate?

Answer 13

The pelvic region and the peroneal region of the obturator internus.

Question 14

From medial to lateral, what are the three muscles of the levator ani?

Answer 14

Puborectalis.

Pubococcygeus.

Iliococcygeus.

Question 15

What portion of the pelvic floor helps promote fecal continence?

Answer 15

The puborectal sling.

Question 16

What two muscles of the pelvic floor are most prone to tearing during childbirth?

Answer 16

The puborectalis and pubococcygeus muscles.

Question 17

The ischiorectal fossa can be divided into what two regions?

Answer 17

The urogenital triangle and the anal triangle.

Question 18

How are the number of vertebrea differ in the coccyx and the sacrum?

How are these two structures joined?

Answer 18

Sacrum 5, coccyx 3

Sacrococcygeal symphysis includes a fibrocartilaginous disc

Question 19

Wher is the true pelvis located?

Answer 19

Aka Pelvis Minor

located inferioir to pelvic bric

Question 20

What componenst of the os coxae comprise the pelvic brim?

Answer 20

Pubic crest

Pecten pubis

Arcuate line

Margin of ala

Sacral promontory

Question 21

What are the bony boundaries of the true pelvis?

Answer 21

sacrum

coccyx

inner sufrace of ischium and pubis

small part of the illium

Question 22

What is the pelvic aperture and what is it bounded by?

Answer 22

Pelvic outlet

Anterior: pubic arch

Lateral: ischial tuberosity

Posteriolateral: sacrotuberous ligament

Posterior: tip of coccyx

Question 23

What is the lumbrosacral join made up of?

Answer 23

intervertabal disc between L5 and S1

plus 2 zygapophysial joins between the articular surfaces of L5 and S1 TPs

Extra: illiolumbar ligament attaches to L5 TP, stabilizing the lumbar spine on the sacrum, thus limiting forward motion of L5 vertebrea.

Question 24

What is the function of the intervertebral disc between the sacrum and the coccyx?

Answer 24

Allows for movement of the coccyx curing defecation or childbirth.

Anterioir and posterior sacrococcygeal ligaments help stabilize the joint.

Question 25

There ar two ligaments stabilizing the pubic symphasis. What are they, and which one is stronger?

Answer 25

They are the inferioir pubic (or arcuate) ligament and the superioir public ligament The arcuate ligament is stronger.

Question 26

What type of joint is the sacroliliac joint? What ligaments stabilize this joint?

Answer 26

Synovial between the lateral surface of S1-S3 and the internal surface of the illium. Interosseous sacroiliac Posterioir sacroiliac iliolumbar sacrotuberous sacrospinous

Question 27

Antero-inferior wall of the pelvic cavity

Answer 27

Formed by bodies and rami of pubic bones and the pubic symphisi It bears the ewight of the urinary bladder

Question 28

Lateral walls of the Pelvic Cavity

Answer 28

Formed by the two hip bones, obturator foramen, and obturator membrane Obturator internus - covers lateral pelvic wall, passses through lesser sciatic foamena to greater trochanter Medial surfaces of IO muscles covered by fascia that thickens centrally to provide attachemnt for the pelvic diaphragm

Question 29

Posterior wall of the Pelvic Cavity

Answer 29

bony structures: sacrum and coccyx the postolateral wall is formed by SI ligaments and the piriformis muscle

Question 30

Pelvic floor

Answer 30

Formed by the pelvic diaphragm which includes the coccygeus and lavator ani (puborectal, pubococcygeal, iliococcygeal) muscles and their fascias. The pelvic diaphragm separates the true pelvis (pelvis minor, or perineum), which contains the exteranl genitalia and the anal canal.

Question 31

Piriformis

Answer 31

**Origin** - lateral masses of S2-S4 vertebrae and the sacrotuberous ligament. **Insertion** - greater trochanter of the femur. Exits the pelvis via the greater sciatic foramen. **Action** - lateral (external) rotator of thigh. **Innervation** - nerve to piriformis (S1-S2).

Question 32

Obturator Internus

Answer 32

**Origin** - anterolateral wall of the pelvis minor and obturator membrane. **Insertion** - greater trochanter. Exits the pelvis via the lesser sciatic foramen. **Action** - lateral (external) rotator of the thigh. **Innervation** - nerve to the obturator internus (L5-S1)

Question 33

Levator Ani

Answer 33

**Dual innervation:** S3-S4 superiorly, and inferior rectal nerve on perineal surface Perforated by urethra and anal canal, as well as vagina in females **Contributors:** Pubococcygeus, Puborectus, Ilicoccygeus mm. **Origin:** body of pubis, ischial spine, tendenous arch **Insertion:** Perineal body (midline)

Question 34

Coccygeus ## Footnote posterior portion of the pelvic diaphrag Origin: ischial spines and sacrospinous ligaments Insertion: lateral surfaces of the anterior sacrum and coccyx. Innervation: S4-S5 Action: supports the coccyx and pull it forward after childbirth or defecation.

Answer 34

Posterior portion of the pelvic diaphragm **Origin:** ischial spines and sacrospinous ligaments **Insertion:** lateral surfaces of the anterior sacrum and coccyx. **Innervation:** S4-S5 **Action**: supports the coccyx and pull it forward after childbirth or defecation.

Question 35

What are the three continuous layers of the pelvic fascia?

Answer 35

Parietal Visceral Diaphragmatic

Question 36

Describe the retropubic space

Answer 36

Between the pubic bones and the anterior bladder, surrounded by fat that allows for expension when bladder is filling/full.

Question 37

Rectovesical space (or pouch)

Answer 37

The recto-vesical pouch is the pocket that lies between the rectum and the urinary bladder in human males and other male mammals. It is lined by peritoneum and at its base is the rectoprostatic fascia (Denonvillier's fascia). When a man is upright or supine, the **recto-vesical pouch is the lowest part of his peritoneal cavity**. In women, the uterus lies between the rectum and the bladder. Therefore, women do not have a recto-vesical pouch, but instead **have a recto-uterine pouch and vesico-uterine pouch**.