PELVIC ANATOMY Flashcards
List the bones which form the “bony pelvis”
- 2 innominate bones (fusion between ilium, ischium and pubis)
- Sacrum
- Coccyx
Where does the iliac crest span from?
from PSIS to ASIS
What part of the pelvis do you sit on?
ischial tuberosity
Where does the inguinal ligament attach?
between the ASIS and pubic tubercle
Name the 5 joints of the pelvis
2 x sacroiliac
2 x hip joint
1 x pubic symphysis (secondary cartilaginous)
How can you palpate the ischial spines?
During vaginal examination, at about a finer breadth into the vagina (approx 4 and 8 o clock positions)
Where does the sacrospinous ligament attach ?
to the sacrum and ischial spine
Where does the sacrotuberous ligament attach?
to the sacrum and ischial tuberosity
Does the pelvic girdle include the coccyx?
no
What is the purpose of the sacrotuberous and sacrospinous ligaments?
ensure the inferior part of the sacrum is not pushed superiorly when weight is suddenly transferred vertically through the vertebral column (e.g. when jumping or during late pregnancy)
What happens to the sacrotuberous and sacrospinous ligaments during later pregnancy?
they relax
Which foraminae are formed by the sacrotuberous and sacrospinous ligaments?
the greater and lesser sciatic
Which bones form the pelvic inlet?
Sacral promontory
Ilium
Superior pubic ramus
Pubic symphysis
Which bones form the pelvic outlet?
Pubic symphysis Ischiopubic ramus Ischial tuberosities Sacrotuberous ligaments Coccyx
What are the borders of the pelvic cavity?
pelvic inlet and pelvic floor
Give 6 functions of the bony pelvis
Support of the upper body when sitting and standing
Transference of weight from one long pole (the vertebral column) to two poles (the femurs) to allow standing and walking
Attachment for muscles of locomotion and abdominal wall
Attachment for external genitalia
Protection of pelvic organs, their blood & nerve supply, their venous and lymphatic drainage
Passage for childbirth
What is the impact of trauma to the bony pelvis?
Life threatening haemorrhage and/or damage to pelvic organs
How is the female pelvis different to the male pelvis?
The AP and transverse diameters are larger at the pelvic inlet and outlet
The suprapubic angle is wider
The pelvic cavity is more shallow
What is “moulding”?
the movement of one bone over another to allow the foetal head to pass through the pelvis during labour
Which structures allow moulding to occur?
sutures and fontanelles
Which structures outline the vertex?
anterior and posterior fontanelles and the parietal eminences
Which foetal head diameter is longer?
occipitofrontal > biparietal
more long than wide
Which diameter is wider at the pelvic inlet?
transverse > AP
What is the station?
the distance of the foetal head from the ischial spines
(-ve = sup to spines)
(+ve = inf to spines)
How should the baby enter the pelvic cavity?
right or left transverse direction then rotate as descending to have a flexed position
Which diameter is wider at the pelvic outlet?
AP > transverse
What position should the baby leave the pelvic cavity?
occipitoanterior (OA) with baby’s head in extension
What happens once the baby’s head has been delivered?
there is a further rotation so that the shoulders and the rest of baby can then be delivered
What nerves and vessels may be damaged as a result of pelvic trauma?
common iliac artery and vein
sacral plexus
