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Pelvic Girdle

Pelvic Girdle

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Pelvic girdle
Pelvic girdle
Additional Images:
Pelvic Girdle
Functions of the Pelvic Girdle:
  • Protect the lower abdominal and pelvic organs
  • Articulate with the bones of the lower extremities
  • Provide attachment sites for muscles and ligaments of the trunk and lower extremity
Right and left pelvic bones:
  • Ilium
  • Ischium
  • Pubis
Posterior Wall:
  • Sacrum and coccyx
Features of Medial Aspect
  • Obturator foramen (space)
    • Round space created by the ischium and pubis.
  • IIlium (Iliac bone)
    • Iliac crest is the bony ridge of the ilium
    • Anterior and posterior superior iliac spines where crest terminates anteriorly and posteriorly
    • Anterior and posterior inferior iliac spines are inferior to superior spines
The iliac spines anchor muscles of the hip and thigh
    • Ala is the broad, flat portion of the ilium below the iliac crest
    • Iliac fossa is the concave portion of the ala, which gives a "bowl" shape to this region of the pelvis
    • Auricular surface and iliac tuberosity are areas of articulation the sacrum
    • Arcuate line is a rounded ridge of bone that sweeps from the auricular surface to the pubis
  • Pubis (Pubic bone)
    • Pectineal line is continuation of arcuate line; these lines are collectively referred to as the linea terminalis
    • Pubic tubercle is a knob-like projection that anchors the inguinal ligament (not shown)
    • Symphyseal surface is where the cartilaginous pubic symphysis attaches to the pubic bone anteriorly
    • Superior and inferior pubic rami are the straight portions of the pubis; they connect with the ilium, superiorly, and the ischium, inferiorly
  • Ischium (Ischial bone)
    • Ischial spine is a small projection of bone that points inferomedially
    • Ischial tuberosity is the large, roughened area of the bone where the hamstrings muscles attach
    • Ischial ramus joins with the inferior pubic ramus
    • Lesser sciatic notch is inferior to the ischial spine
Greater sciatic notch is bound by the ischial spine and the posterior inferior iliac spine*
Unique Features of Lateral Aspect:
  • Acetabulum is the deep, cup-like depression where the head of the femur (aka, thigh bone) articulates with the pelvic bone;it marks where ilium, ischium, and pubis meet and fuse
  • Lunate surface is the c-shaped smooth area inside the acetabulum
Gluteal surface of ala is marked by gluteal lines* (anterior, posterior, and inferior)
Additional key terminology and landmarks of the pelvis:
  • Pelvic brim is formed by the superior edges of the sacrum, arcuate and pectineal lines, and pubic symphysis
    • Encloses the pelvic inlet
  • Pelvic inlet, aka, aperture, is the circular opening between the abdominal and pelvic cavities (so, the brim comprises the edges of bone, the inlet is the space).
    • Pelvic inlet divides the pelvis into false and true pelvises:
Superiorly, the false (aka, greater) pelvis is bound by the alae of the ilium and the S1 vertebra; it contains the lower abdominal viscera. Inferior true (aka, lesser) pelvis contains the pelvic viscera and deep perineum.
  • Pelvic outlet is the diamond-shaped opening enclosed by the: pubic arch, ischial tuberosities, coccyx, and sacrotuberous ligaments.
Sexual Dimorphism
Photos from:
https://sites.google.com/a/umich.edu/bluelink/resources/bluelinks/labeled-bones-joints-and-movement-images

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