Osteology of the Pelvis Flashcards
What are the functions of the pelvis?
- Weight transfer – from axial to lower appendicular skeleton
- Withstand compression and other forces
- Provide attachment for powerful muscles
Name the bones that make up the bony pelvis in a mature person?
- Hip bones
- Ilium
- Ischium
- Pubis
- Sacrum – 5 fused sacral vertebrae
- Coccyx – 4 fused coccygeal vertebrae
Describe the bones of the bony pelvis in an infant?
hip bones consist of 3 separate bones (ilium, ischium and pubis) united by cartilage at acetabulum
- Fuses at Puberty
Another name for hip bones in an infant is?
coxal bones or innominate bones
Name the 4 pelvic joints?
1. Pubic symphysis – joins two hip bones together 2. Sacroiliac joint – joins hip bones to sacrum 3. Lumbosacral joint – joins vertebrae to sacrum 4. Sacrococcygeal joint – joins sacrum to coccyx
Name the parts of the ilium?
- ala – wing
- Iliac crest
- Anterior and posterior superior + inferior iliac spines
- Iliac fossa
- Body – forms acetabulum
Name the parts of the ischium?
- Body – forms the acetabulum
- Ramus – forms obturator foramen
- Ischial tuberosity
- Ischial spine – posterior projection between body and ramus
- Lesser sciatic notch – concavity between ischial tuberosity and spine
Name the parts of the pubis?
- superior ramus – form acetabulum
- Inferior ramus – form obturator foramen
- Pubic crest – anterior thickening of the body
- Pubic tubercle – lateral prominent bump
- Pecten tubercle (Pectineal line of pubis) – oblique ridge on the ramus
The bony pelvis is divided into what 2 regions?
- Greater pelvis (false pelvis, pelvis major)
- Lesser pelvis (true pelvis, pelvis minor)
- separated by an oblique plane that forms the pelvic inlet
Describe the location of the greater pelvis and its contents?
- Superior to pelvic inlet
- Location for abdominal viscera
e. g. ileum and sigmoid colon
What are the boundaries of the greater pelvis?
- Anteriorly – abdominal wall
- Posterior laterally – iliac fossa
- Posteriorly – L5 and S1 vert.
- Inferior – pelvic inlet
Describe the location of the lesser pelvis and its contents?
- Between pelvic inlet and outlet
- Forms the pelvic canal (birth canal)
- Location of pelvic viscera e.g. urinary bladder + reproductive organs
- Major obstetrical and gynecological significance
Describe the boundaries of the lesser pelvis?
- Bounded by pelvic surfaces of hip bones and sacrum + coccyx
- Limited inferiorly by musculofascial pelvic diaphragm
Note: this is true pelvic cavity - abdominopelvic cavity
Describe the pelvic inlet (oblique plane)?
- passes from the sacral promontory to terminal lines (lineae terminales)
- Its edges (or rim) forms the pelvic brim
- Oblique plane forms an angle of 55 degrees to the horizontal
What are the boundaries to the pelvic inlet?
- Anterior - superior margin of pubic symphysis
- Posterior - sacral promontory + sacral ala
- Lateral - Arcuate line of ilium + pectineal line on superior pubic ramus
- Inferior- pelvic diaghram
What are the boundaries of the pelvic outlet?
- Anterior – inferior margin of the pubic symphysis (pubic arch)
- Anterolateral – inferior rami of pubis and ischial tuberosities
- Posterolateral– sacrotuberous ligament
- Posterior – tip of coccyx