Abdomen: Pelvis Flashcards
Pelvic girdle
- Coxal bones
- Articulate posteriorly with the sacrum (forms the pelvic skeleton/pelvic ring)
Coxal bones
- Ilium
- Ishium
- Pubis
Coccyx is often included as
- Part of the pelvic skeleton
Pelvic girdle function
- Strong and rigid
- Connects vertebral column to lower extremity
- Weight transfer
- Muscle attachment
- Protect and support pelvic/abdominal viscera
Pelvis subdivisions
- Greater pelvis
- Lesser pelvis
Greater pelivis
- Superior to pelvic inlet
- Surrounded by superior pelvic girdle
- Abdominal viscera
Lesser pelvis
- Inferior to pelvic inlet, superior to pelvic outlet
- Pelvic cavity
- Surrounded by inferior pelvic girdle
Perineum
- Inferior to pelvic floor
- Between coccyx to pubic symphysis
- External genitalia, anus
Coxal bone
- os coxae, hip bone
- 3 separate bones
- Multiple secondary centers
Coxal bones are separated by
- Triradiate cartilage
Coxal bone development
- Begins to fuse around puberty
- Completely fused by early 20s
Coxal bone articulates with
- Sacrum posteriorly (sacroiliac joint)
- Contralateral coxal bone anteriorly (pubic symphysis)
- Femur laterally (acetabofemoral joint, hip joint)
Function of the Pelvis
- Weight transfer
- Muscle and ligament attachment
- Protect abdominopelvic viscera
Pelvic inlet (superior pelvic aperture)
- Passageway between greater and lesser pelvis
- Pelvic brim: edge of the pelvic inlet
Pelvic inlet is formed by
- Linea terminalis
- Pubic crest and symphysis
Linea terminalis
- Sacral promontory
- Sacral ala
- Arcuate line
- Pectineal line
- Pubic crest and symphysis
Arcuate line
- Rounded inner border of ilium
- Inferior to iliac fossa
Pectineal line
- Ridge on superior pubic ramus
The arcuate and pectineal lines are called
- iliopectinal lines
Pelvic outlet (inferior pelvic aperture) boundaires
- Anterior: Pubic arch (formed by ischiopubic rami)
- Lateral: ischial tuberosities
- Posterolateral: sacrotuberous ligament
- Posterior: coccyx
Pelvic outlet (inferior pelvic aperture) POSTERIOR boundary
- Coccyx
Pelvic outlet (inferior pelvic aperture) ANTERIOR boundary
- Pubic arch (formed by ischiopubic rami)
Pelvic outlet (inferior pelvic aperture) LATERAL boundary
- Ischial tuberosities
Pelvic outlet (inferior pelvic aperture) POSTEROLATERAL boundary
- Sacrotuberous ligament
ASIS and superior edge of pubic symphysis are
- In the same vertical plane
Inlet angle
- 50-60 degrees above horizontal plane
Pelvic cavity projects
- Posteriorly
Other passageways in/out of the pelvis
- Greater sciatic foramen
- Lesser sciatic foramen
- Obturator foramen
Greater sciatic foramen
- Passageway to gluteal region
Greater sciatic foramen Boundaries
- Greater sciatic notch (ilium) is anterior (anterolateral)
- Anterior sacroiliac ligaments are superior
- Ischial spine and sacrospinous ligament are inferior
- Sacrotuberous ligament is posterior (posteromedial)
Greater sciatic foramen ANTERIOR boundary
- Greater sciatic notch/ilium (anterolateral)
Greater sciatic foramen SUPERIOR boundary
- Anterior sacroiliac ligaments
Greater sciatic foramen INFERIOR boundary
- Ischial spine and sacrospinous ligament
Greater sciatic foramen POSTERIOR boundary
- Sacrotuberous ligament (posteromedial)
Lesser sciatic foramen
- Passageway to gluteal region/perineum
Lesser sciatic foramen boundaries
- Lesser sciatic notch (ischium) is anterior
- Ischial tuberosity is anterior, inferior
- Ischial spine is anterior, superior
- Sacrospinous ligament is superior
- Sacrotuberous ligament is posterior
Obturator foramen
- Mostly covered by obturator membrane
- Passageway to medial thigh
Obturator canal (in obturator foramen)
- Superior opening between obturator membrane and superior pubic ramus
Sacroiliac joint (SI)
- Sturdy, designed for weightbearing
- Interlocking bony auricular surfaces of ilium and sacrum
- 2 parts
2 parts of sacroiliac joint
- Anterior synovial joint (limited motion)
- Posterior syndesmosis, fibrous join
Ligaments of the sacroiliac joint
- Anterior sacroiliac
- Interosseous sacroiliac
- Posterior sacroiliac
- Iliolumbar
- Sacrotuberous & sacrospinous ligaments
Interosseous sacroiliac ligament
- Connect tuberosities of sacrum/ilium
- Weight transfer
Sacrotuberous & sacrospinous ligaments
- Resist anterior/inferior motion of sacrum
- Superior rotation of pelvis (weight-bearing)
Pubic symphysis
- Fibrocartilaginous joint (Symphysis joint)
- Superior and inferior pubic ligaments
Lumbosacral joint
- L5/S1
- Synovial joint between articular facets
- Symphysis joint between L5 body and sacral base
Male vs. Female pelvis
- Differences due to body size/muscle mass
- Adaptation for childbearing and birth
Male pelvis
- Larger/heavier
- Narrow and deep lesser pelvis
- Comparatively smaller pelvic inlet/outlet
- Narrower subpubic angle and greater sciatic notch
- Round obturator foramen
- Longer sacrum
- Mostly android shaped pelvis
Female pelvis
- Lighter
- Shallower/wider greater and lesser pelvis
- Inlet/outlet are comparatively wider
- Inlet more oval
- Obturator foramen is smaller and triangular shaped
- Acetabulum faces more anteriorly
- Wider subpubic angle and greater sciatic notch
- Mostly gynecoid shaped pelvic inlet