Pelvic girdle Pelvic girdle Additional Images: Pelvic GirdleFunctions 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 extremityRight and left pelvic bones: • Ilium • Ischium • PubisPosterior 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 DimorphismPhotos from: https://sites.google.com/a/umich.edu/bluelink/resources/bluelinks/labeled-bones-joints-and-movement-images