Pelvic Bone Anatomy Quiz

The Pelvis

• The pelvis is composed of four bones: two innominate bones, the sacrum, and the coccyx.
• The innominate bones are formed by the fusion of three bones: the ilium, ischium, and pubis.

The Pubis

• The pubis is a bony projection situated lateral to the pubic crest.
• The superior pubic ramus extends laterally from the body and joins the ilium to form part of the acetabulum.
• The inferior pubic ramus meets with the ischial ramus to form the ischiopubic ramus.
• The obturator foramen is formed by the superior pubic ramus and ischiopubic ramus.
• Through the obturator foramen, the obturator nerve, artery, and vein pass to reach the lower limb.

The Ischium

• The ischium is an L-shaped bone that forms the postero-inferior part of the hip bone.
• The body is the upper thick part of the ischium.
• The ischial spine projects from the posterior border of the body of the ischium.
• The ischial tuberosity is the thick postero-inferior aspect of the bone.
• The ischial ramus combines with the inferior pubic ramus to form the ischiopubic ramus.

The Sacrotuberous and Sacrospinous Ligaments

• The sacrospinous ligament runs from the ischial spine to the sacrum.
• The sacrotuberous ligament runs from the sacrum to the ischial tuberosity.
• These two ligaments convert the greater and lesser sciatic notches into foramina.

The Ilium

• The iliac crest is situated at the upper border of the ilium.
• The anterior superior iliac spine (ASIS) is situated at the anterior end of the iliac crest.
• The anterior inferior iliac spine (AIIS) is a rounded prominence situated below the ASIS.
• The posterior superior iliac spine (PSIS) is situated at the posterior end of the iliac crest.
• The posterior inferior iliac spine (PIIS) is located below the PSIS.
• The iliac tubercle lies about 5 cm behind the anterior superior spine.
• The greater sciatic notch is an indentation on the posterior aspect of the body of the ilium, above and behind the acetabulum.

The Sacroiliac Joint

• The sacroiliac joint is a synovial plane joint.
• The articular surfaces are the auricular surface of the ilium and the auricular surface of the sacrum.
• The ligaments are the anterior sacroiliac ligament, posterior sacroiliac ligament, sacrotuberous ligament, and sacrospinous ligament.
• The innervation is by S1-S2 spinal nerves and the superior gluteal nerve.
• The movements are slight gliding and rotatory movements.

The Acetabulum

• The acetabulum is a cup-shaped depression on the outer surface of the hip bone.
• It is formed by the three hip bones.
• It articulates with the spherical head of the femur to form the hip joint.

The Femur

• The femur is the longest bone in the body.
• The proximal end consists of the head, neck, and greater and lesser trochanters.
• The distal end consists of the medial and lateral condyles.
• The head forms about two-thirds of a sphere and articulates with the acetabulum of the hip bone to form the hip joint.