Lecture 17 DA

Question 1

What contains the pelvic viscera?

Answer 1

The lesser pelvis, found within the pelvis, It is the true pelvis.

Question 2

What is found above the true pelvis?

Answer 2

The false pelvis. It has no bony anterior border.

Question 3

What seperates the true and false pelvises?

Answer 3

The iliopectineal line. Pectineus muscle attaches here.

Question 4

How do female pelvises differ from male ones?

Answer 4

They are wider, with a bigger true pelvis. The sub pubic arch is very wide and open, but acute in males.

Question 5

What is the shape of the pelvic inlet in males vs females?

Answer 5

In males, it is heart-shaped, while in females it is wider and oval-shaped.

Question 6

How do the ischial spine differ between male and females?

Answer 6

In males, it projects medially, but not in females.

Question 7

What are the percentages for pelvic shape type?

Answer 7

Gynaecoid (ideal for foetus passage) - 50%
Android (narrower and longer, true pelvis is funnel shaped) - 30%
Anthropoid (closer to apes) - 18%
Platypelloid (flattened and wider) - 2%

Question 8

How is the pelvis oriented? Why is this so? Is there sexual dimorphism?

Answer 8

Pelvis is tilted forwards, pubic bone is more superior.
Lumbar spine has a lordotic curvature, hence the tilt.
Females have a more pronounced lordosis, so bigger tilt.

Question 9

What filles the obturator foramen?

Answer 9

Obturator membrane.

Question 10

What are the ilium, ischium and pubis? Where do they join?

Answer 10

They are epiphyseal plates. They join at the acetabulum.

Question 11

What plane are the ovaries or seminal vesicles found?/

Answer 11

Plane connecting the tip of the coccyx to the pubic bone.

Question 12

What shape is the inlet and outlet?

Answer 12

Inlet iis circular while outlet is diamond shaped, formed from two triangles, the urogenital anterior and anal triangle posterior.

Question 13

Where is the narrow pelvic plane that a foetal (dont invade plz) head must pass through?

Answer 13

S4-inferior pubic symphysis.

Question 14

How does the foteal head pass through the narrow pelvic plane?

Answer 14

Head comes in transversely, fits through the pelvic inlet. The skull is smaller than the inlet and is rotated by the pelvic floor. Chin is pushed against its chest, narrowest diameter.

Question 15

During birth, what happens if a child’s chin doesn’t press against its chest?

Answer 15

Diameter can increase by up to 4cm, harder to give birth.

Question 16

What are fontanelles?

Answer 16

Spaces that allow cranial bones to slide across each other and make birth easier.

Question 17

What are the 5 apertures of the pelvis?

Answer 17

The pelvic inlet.
Interior sacral foraminae to the back.
Obturator canal – to lower limb, via obturator foramen.
Greater sciatic foramen, to lower limb.
lesser sciatic foramen, to perineum and gluteal.

Question 18

What is the most important bone in forensic investigation?

Answer 18

Pelvis.

Question 19

What are some clues in the pelvis for age?

Answer 19

Pubic symphysis has transverse ridges which disappear in old age, becoming more osteophytic.

Question 20

What is a consequence of the weight of the abdomen on the pelvis? What is it resisted by?

Answer 20

Causes the pelvis to want to rotate further forward, along the axis of S2. Resisted by interosseus sacroiliac, sacrospinous, sacrotuberous and iliolumbar ligaments.

Question 21

What is the reverse keystone effect?

Answer 21

Sacrum sinks forward into the pelvis, posterior ligaments are drawn tight and draw iliac bones together. Increases stability.

Question 22

What kind of joint is the pubic symphysis?

Answer 22

Secondary cartilaginous joint.

Question 23

Describe the sacroiliac joint.

Answer 23

Synovial at the front, fibrous at the back.

Question 24

What do posterior pelvic ligaments do?

Answer 24

Resist nutation.

Question 25

Is there any movement in the pelvic joint?

Answer 25

Very little movement occurs, only 2-8 degrees. Happens most when you stand from prone position.

Question 26

What happens to degree of movability in the pelvic joint during pregnancy? What is a complication regarding this?

Answer 26

It increases due to the action of relaxin. It can tighten in the wrong orientation, and cause pain.

Question 27

What nerve roots is the pelvic joint supplied by?

Answer 27

It is supplied by L5-S2, so pain will be in the back buttock.

Question 28

What tendon can be found at the sacroiliac joint?

Answer 28

An X-shaped tendon, formed from the latissimus dorsi and gluteal muscles. Strengthens the muscles and enhances the joint.

Question 29

What is found in the pubic sympysis? what is a complication regarding this?

Answer 29

A fibrocartilaginous disc is found in between the bone. It can split during pregnancy.

Question 30

What is the pubic symphysis reinforced by?

Answer 30

Superior pubic ligament above, and inferior arcuate ligament below.

Question 31

What prevents lateral seperation of the pubic symphysis?

Answer 31

Adductor longus links with internal oblique fibres in a criss-cross fashion, forming a tie-beam. Rectus abdominus and transversus abdominus also prevent lateral seperation.

Question 32

How do pelvic fractures most frequently happen?

Answer 32

Motor vehicle accidents. Usually only occurs due to trauma.

Question 33

What is the most common damage to pevlis in children?

Answer 33

Avulsion fractures as the bone is still soft.

Question 34

What is the ring phenomenon?

Answer 34

If a ring structure (or spherical) is fractured at one site, then another will be found at another site, most likely diametrically opposite.