repro 4.2 osetology of the pelvis Flashcards
What 4 bones make up the pelvis?
2 inonimate bones
sacrum
coccyx
What are the features of the innonimate bones? (hip bones)
iliac crest
the ischial spine
ischial tuberosits
What is the linea terminalis?
The point at which you enter the true pelvis from the false pelvis.
Made of:
- pubic crest
- pectineal line
- arcuate line
What problems may be caused by the sacrum?
The sacral pomontory may cause problems with the birthing of the foetus.
What are the borders of the pelvic inlet?
-linea terminalis (pubic crest, pectinate line, arcuate line)
-sacral ala
Sacral promontory
What is the name given to a pelvis which is ideal for birth?
Gynecoid
What are features of a gynecoid pelvis?
- round pelvic inlet
- straight pelvic walls (not tapered)
- not too prominent ischial spines
- well rounded greater sciatic notch
- well curved sacrum
- sub pubic arch >90 degrees
What is the true pelvis?
The solid bony canal of the pelvis which is of obstetric relevance.
What is the false pelvis?
The part of the pelvis above the pelvic inlet.
Has no obstetric relevance as it is more than big enough for the foetus.
What are the 4 pelvic planes?
- pelvic inlet
- plane of greatest diameter
- plane of least diameter
- pelvic outlet
What is the pelvic inlet?
- linea terminalis
- sacrum
- coccyx
- pubic symphesis
What is the plane of greatest diameter?
- the AP diameter from the posterior pubic symphesis to the junction between S2/3.
- Laterally is between the acetabulum through the ischial spines.
What is the plane of least diameter?
-AP from the posterior pubic symphesis to the junction between S4/5.
What is the pelvic outlet?
- pubic symphesis
- ichiopubic rami
- ischial tuberosities
- sacrotuberous ligaments
- tip of the coccyx.
What do midwives assess to see if the female is likely to have difficulty giving birth?
- AP diameter. (via palpation)
- straight walls of the pelvis
- bi-spinous diameter (too small, foetus may get stuck)
- infrapubic angle
- distance between ischial tuberosities.
What are the conjugates of the pelvis?
- obstetric conjugate
- diagonal conjugate (measured)
They measure the minimum AP diameter of the pelvis
How do you measure/what is the obstestric conjugate?
from the sacral promontory to the mid point of the pubic symphesis.
How do you meausre/what is the diagonal conjugate?
from the sacral promontory to the inferior border of the pubic symphesis.
What are the ligaments of the pelvis?
sacrospinous ligament (sacrum to ischial spine)
sacrotuberous ligaments (sacrum to ischial tuberosity)
What’s the function of the pelvic ligaments during birth?
They allow a little bit of movement of the pelvis during childbirth. Allow a bit of ‘give’
During pregnancy, what hormone is released to allow easier birthing?
Progesterone, allows for slight softening of the pelvic joints and ligaments, to allow them to move more during birth.
What different features are there in an android pelvis compared to a gynecoid pelvis?
- tapering walls
- smaller angle of sub-pubic arch
- heavier pelvis
- heart shaped outlet (instead of round)
- narrower true pelvis
- more prominent ischial spines (–> less well rounded greater sciatic notch)
The pubic inlet is the point of division between what 2 parts of the pelvis?
- false pelvis
- true pelvis
Why can you not directly measure the obstetric conjugate during examination?
The bladder is in the way
What does the sacrotuberous ligament lead to the formation of?
The sciatic foreamen
What does the sacrospinous ligament lead to the formation of?
The division of the sciatic foramen into the greater and lesser sciatic foramen.
