Flashcards in Lecture 17 DA Deck (34):
What contains the pelvic viscera?
The lesser pelvis, found within the pelvis, It is the true pelvis.
What is found above the true pelvis?
The false pelvis. It has no bony anterior border.
What seperates the true and false pelvises?
The iliopectineal line. Pectineus muscle attaches here.
How do female pelvises differ from male ones?
They are wider, with a bigger true pelvis. The sub pubic arch is very wide and open, but acute in males.
What is the shape of the pelvic inlet in males vs females?
In males, it is heart-shaped, while in females it is wider and oval-shaped.
How do the ischial spine differ between male and females?
In males, it projects medially, but not in females.
What are the percentages for pelvic shape type?
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%
How is the pelvis oriented? Why is this so? Is there sexual dimorphism?
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.
What filles the obturator foramen?
What are the ilium, ischium and pubis? Where do they join?
They are epiphyseal plates. They join at the acetabulum.
What plane are the ovaries or seminal vesicles found?/
Plane connecting the tip of the coccyx to the pubic bone.
What shape is the inlet and outlet?
Inlet iis circular while outlet is diamond shaped, formed from two triangles, the urogenital anterior and anal triangle posterior.
Where is the narrow pelvic plane that a foetal (dont invade plz) head must pass through?
S4-inferior pubic symphysis.
How does the foteal head pass through the narrow pelvic plane?
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.
During birth, what happens if a child's chin doesn't press against its chest?
Diameter can increase by up to 4cm, harder to give birth.
What are fontanelles?
Spaces that allow cranial bones to slide across each other and make birth easier.
What are the 5 apertures of the pelvis?
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.
What is the most important bone in forensic investigation?
What are some clues in the pelvis for age?
Pubic symphysis has transverse ridges which disappear in old age, becoming more osteophytic.
What is a consequence of the weight of the abdomen on the pelvis? What is it resisted by?
Causes the pelvis to want to rotate further forward, along the axis of S2. Resisted by interosseus sacroiliac, sacrospinous, sacrotuberous and iliolumbar ligaments.
What is the reverse keystone effect?
Sacrum sinks forward into the pelvis, posterior ligaments are drawn tight and draw iliac bones together. Increases stability.
What kind of joint is the pubic symphysis?
Secondary cartilaginous joint.
Describe the sacroiliac joint.
Synovial at the front, fibrous at the back.
What do posterior pelvic ligaments do?
Is there any movement in the pelvic joint?
Very little movement occurs, only 2-8 degrees. Happens most when you stand from prone position.
What happens to degree of movability in the pelvic joint during pregnancy? What is a complication regarding this?
It increases due to the action of relaxin. It can tighten in the wrong orientation, and cause pain.
What nerve roots is the pelvic joint supplied by?
It is supplied by L5-S2, so pain will be in the back buttock.
What tendon can be found at the sacroiliac joint?
An X-shaped tendon, formed from the latissimus dorsi and gluteal muscles. Strengthens the muscles and enhances the joint.
What is found in the pubic sympysis? what is a complication regarding this?
A fibrocartilaginous disc is found in between the bone. It can split during pregnancy.
What is the pubic symphysis reinforced by?
Superior pubic ligament above, and inferior arcuate ligament below.
What prevents lateral seperation of the pubic symphysis?
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.
How do pelvic fractures most frequently happen?
Motor vehicle accidents. Usually only occurs due to trauma.
What is the most common damage to pevlis in children?
Avulsion fractures as the bone is still soft.