anatomy of pelvic bones Flashcards
bony pelvis consists of what structures?
- 2 hip bones
- sacrum
- coccyx
each hip bone is a fusion between?
- ilium
- ischium
- pubis
complete ossification does not happen until adulthood
iliac fossa is the attachment site for which muscle?
- illiacus muscle
ASIS anterior end of what?
- iliac crest
-> bony landmark
iliac crest runs from?
- ASIS to PSIS
ilium contains what 4 structures?
- iliac crest
- ASIS
- PSIS
- iliac fossa
ischium contains what 3 structures?
- ischiopubic ramus
- ischial spine
- ischial tuberosity - posterior parts feel when you sit down
pubis anteriorly contains what structures?
- ischiopubic ramus
- superior pubic ramus
- pubic tubercle
- pubic arch (connection between ischiopubic ramus)
- sub-pubic angle (inferior angle to pubic arch)
hip bones form a ring closed anteriorly and posteriorly by what?
anteriorly - pubic symphysis
posteriorly - sacrum
pelvic inlet is the entry for what?
- pelvic cavity proper from abdominal cavity
-> known as pelvic rim
pelvic inlet is made up of what structures?
- sacral promontory
- ilium
- superior pubic ramus
- pubic symphysis
pelvic outlet is made up of what structures?
- pubic symphysis
- ischiopubic ramus
- ischial tuberosities
- sacrotuberous ligaments
- coccyx
what is pelvic outlet?
- inferior aspect of pelvic cavity
what is pelvic cavity?
- space lying within bony pelvis
- continuous w abdominal cavity above
- lies between pelvic inlet and pelvic floor
- contains pelvic organs as well as supporting tissues
the inguinal ligament attaches between the ASIS and the ?
- pubic tubercle
ischial spines are palpable on vaginal examination at what clock positions?
- 4
- 8 o’clock
list some palpable surface landmarks of the pelvis?
- ASIS
- pubic symphysis
- pubic tubercle
- iliac crest - posterior
- sacrum - posterior
- PSIS - posterior
- coccyx - posterior
- ischial tuberosity - posterior
study bony pelvis
study
study
name 3 joints of pelvis?
- hip joint (synovial) - between head of femur and acetabulum
- pubic symphysis (secondary cartilaginous) - post natal and pregnancy pain here
- sacroiliac joint (synovial but described as synovial ant and syndesmosis posteriorly)
function of SI joint
- transfer weight from axial skeleton to hip bones
large number of ligaments of pelvis what are 2 most important ones?
- sacrotuberous ligament
- sacrospinous ligament
sacrotuberous ligament attaches to what 2 structures?
- sacrum and ischial spine
sacrospinous ligament attaches to what 2 structures?
- sacrum and ischial spine
ligaments of pelvis function?
- protection against sudden weight transfer - help resist superior movement of pelvis
- ligaments relax during later pregnancy (hormone called relaxin)
sacrospinous and sacrotuberous ligaments forms 2 foraminae what are these?
- greater and lesser sciatic foraminae
where is obturator foramen found
- found at anterior aspect of pelvis
what is obturator foramen covered by
- obturator membrane
- however obturator canal - obturator neuro vasc bundle which supplies medial aspect of thigh
what covers obturator foramen internally?
- obturator internus muscle
what covers obturator foramen internally?
- obturator internus muscle
> this is covered by obturator fascia - thickens centrally - forms tendinous arch - which is an attachment for pelvic floor
ring shaped bones tend to fracture in more than one place? true or false?
- true
- think of trying to break a pretzel
what is blood supply near bony pelvis?
- common iliac artery
- common iliac vein
what is nerve supply near bony pelvis?
- sacral nerves/plexus
if bony pelvis is damaged - serious risk to what structures?
pelvic organs:
- bladder
- uterus
- rectum
- life threatening haemorrhage
the AP and tranverse diameters of female pelvis are larger than male, both at pelvis inlet and outlet true or false?
- true
the subpubic angle (and pubic arch) in male is wider than in the female true or false?
- false
- wider in female
the pelvic cavity is more shallow in the female true or false?
- true
what is moulding?
- refers to movement of bone over another to allow foetal head to pass through pelvis during labour
what are fontanelles?
- membrane between bone in brain - areas not formed into bone yet
name fontanelles?
- anterior - between frontal and parietal
- occipital - between parietal and occipital
- lateral
when do fontanelles typically close
- 18 months - 2 years
what is largest fontanelle?
- anterior fontanelle
what is the vertex of the skull?
- area of foetal skull: outlined by anterior and posterior fontanelles and parietal eminences
what are parietal eminences?
- bony looking bumps of lateral aspects of skulls
- points of secondary ossification - eventually become rounded bone
what is the occiptofrontal diameter
- diameter running from occipital bone to frontal bone
what is biparietal diameter?
- running between parietal eminences
what diameter is considered longer?
- occipitofrontal diameter
pelvic inlet: transverse diameter of pelvis is wider than AP diameter true or false?
- true
if transverse diameter is wider which way should fetal skull come out?
- foetus should enter into pelvic cavity facing transversely i.e. right or left
ischial spines can indicate what?
- the distance of foetal head from ischial spines
- this distance is referred to as the station
> a negative no means head is superior to spines
> positive number means head is inferior to spines (descended further)
pelvic outlet: AP diameter is wider than transverse diameter true or false?
- true
babys head should rotate again to leave pelvic cavity in what position?
occipitoanterior (OA) position (ie occipito part of baby should be at anterior part of mother)
baby should descend through pelvic cavity and head should do what two things?
- rotate
- be in a flexed position i.e. chin on chest
describe from descent the movement of baby into and out of pelvic cavity?
- at pelvic inlet, foetal head should be transverse
- as it descends through cavity, foetal head should rotate and it should be flexed
- at pelvic outlet, foetal head should ideally lie occipitoanterior (OA) and extension of the head and neck should occur.
describe from descent the movement of baby into and out of pelvic cavity?
- at pelvic inlet, foetal head should be transverse
- as it descends through cavity, foetal head should rotate and it should be flexed
- at pelvic outlet, foetal head should ideally lie occipitoanterior (OA) and extension of the head and neck should occur.
- once foetal head has been delivered, there is a further rotation - so rest of baby can be delivered - shoulders in AP position of pelvic outlet
