Pelvic Anatomy Study Notes

Ilium: The largest and uppermost bone of the pelvis, forming the superior part of the acetabulum.
- Iliac fossa: A large, smooth, concave surface on the internal side of the ilium, which serves as a site for muscle attachment.
- Anterior superior iliac spine: A prominent, palpable bony projection located at the most anterior and superior point of the iliac crest. It is an important anatomical landmark.
- Anterior inferior iliac spine: A bony projection situated inferior to the anterior superior iliac spine, on the anterior border of the ilium. It serves as an attachment point for the rectus femoris muscle and iliofemoral ligament.

Ischium: The posterior and inferior part of the hip bone, contributing to the formation of the acetabulum and defining the posterior aspect of the obturator foramen.
- Ischial tuberosity: A large, roughened protuberance on the inferior part of the ischium, often referred to as the "sit bone." It supports the weight of the body when sitting and provides attachment for hamstring muscles.
- Lechial tuberosity: This term appears in the original text and is highly likely a typographical error for Ischial tuberosity.
- Ischiopubic ramus: A bony strut formed by the fusion of the inferior pubic ramus and the ischial ramus, enclosing the obturator foramen medially and inferiorly.

Pubic bone: The anterior part of the hip bone, contributing to the formation of the acetabulum and articulating with its counterpart at the pubic symphysis.
- Pubic crest: The thickened superior border of the body of the pubic bone, providing attachment for abdominal muscles.
- Pubic symphysis: The cartilaginous joint that unites the bodies of the left and right pubic bones, allowing for slight movement.
- Ischiopubic ramus: As described above, this structure is a shared component formed by the fusion of parts of the ischium and pubis.

Sacrum: A large, triangular bone formed by the fusion of five sacral vertebrae, located at the base of the spine and forming the posterior wall of the pelvis.
- Sacral promontory: The prominent anterior-most projection of the superior border of the first sacral vertebra ( $S_1$ ). It forms part of the pelvic brim and is an important obstetric landmark.

Coccyx: Often referred to as the "tailbone," this is a small, triangular bone typically formed by the fusion of three to five rudimentary vertebrae, located at the inferior end of the sacrum.

Acetabulum: A large, cup-shaped socket on the lateral aspect of the hip bone. It is formed by contributions from the ilium, ischium, and pubis, and articulates with the head of the femur to form the hip joint.
Obturator foramen: A large opening in the hip bone, formed by the ischium and pubic bone. It is largely covered by the obturator membrane, through which the obturator nerve and vessels pass to reach the medial compartment of the thigh.