Repro 5.2 The Pelvis Flashcards
What shape is the bony pelvis?
Funnel shaped
What structures make up the pelvis?
Inominate (hip) bones
Sacrum
Coccyx
Dense ligaments bind the bones to each other
What is the superior aperture?
The pelvic inlet
What is the inferior aperture?
The pelvuc outlet (narrower than the inlet)
What demarcates the pelvic inlet?
The broad wings of the iliac bones, the sacrum and the pubic symphysis
What demarcates the pelvic outlet?
Paired inferior rami
Ischial bone
Ischial spines
Coccyxx
What is the position of the pelvis in the erect position?
Tilted so that the plane of its inlet is at an angle of 60 degrees to the horizontal
What is the greater pelvis?
The false pelvis - the space surrounded by the upper portion of the iliac bones and upper part of the sacrum posteriorly (actually the lower portion of the abdominal cavity)
What is the lesser pelvis?
The true pelvis - More deep than the false pelvis, surrounded by the obturator foramen and ischial spines and the lower portion of the sacrum (contains the true structures of the pelvis - internal genitalia and the bladder)
What are the important muscular diaphragms in the pelvis?
Urogenital diaphragm
Pelvic diaphragm
What do the pelvic and urogenital diaphragms do?
close off the pelvic outlet and form a barrier between the visceral contents of the pelvis and the exterior
What are the 2 main differences between male and female pelvises?
- The heavier build and stronger muscles in the male account for the stronger bone structure and better-defined muscle markings
- Comparatively wider and shallower pelvic cavity in the female is correlated with its specialisation to accommodate the passage of the infant’s head
What other features distinguish the male and female pelves on plane x-rays?
The pelvic inlet is heart-shaped in the male and oval in the female
The subpubic angle (angle between the inferior pubic rami) is narrow in the male and wide in the female
The soft tissue shadow of the penis and scrotum can usually be seen when not shielded by a lead screen
What is the pelvic floor?
Muscular and fibrous tissue diaphragm that fills the lower part of the pelvic canal and closes the abdominal cavity. It defines the upper border of the perineum and supports the pelvic organs
What is the function of the pelvic floor?
Contributes to continence - sphincter mechanism directly and indirectly on vagina and rectum and can resist increases in intra-abdominal pressure associated with coughing, defecation, heavy lifting etc.
Contributes to childbirth and truncal stability
Retains uterus and bladder in correct position