Label the Structures of the Pelvis

All 14 parts on the diagram

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Start here: 9 main parts 9

Ilium The fan-shaped upper part of the hip bone and its largest part. Joined to the sacrum at the sacroiliac joint.
Iliac crest The curved upper margin of the ilium, felt along the waistline.
Anterior superior iliac spine The rounded front end of the iliac crest. Felt at the front of the hip. Thigh muscles attach to it.
Acetabulum The socket where the hip bone meets the head of the femur. Together they form the hip joint.
Ischium The lower back part of the hip bone. It supports the body when sitting.
Obturator foramen The large opening in the hip bone. It lies between the pubis and the ischium.
Pubis The front part of the hip bone. It has a body and upper and lower rami. It meets the opposite pubis at the pubic symphysis.
Pubic symphysis The joint where the two pubic bones meet at the front.
Sacrum The triangular bone at the back of the pelvis. It sits between the two hip bones.

The hip bone: 10 3

Iliac fossa The shallow depression on the inner surface of the upper ilium.
Anterior inferior iliac spine A rounded bump below the anterior superior iliac spine. Also for thigh muscles.
Ischial tuberosity The large roughened bottom of the ischium. It carries the body's weight when sitting.

Sacrum, coccyx and joints: 4 2

Coccyx The tailbone, at the lower end of the sacrum.
Sacroiliac joint The largely immobile joint between the sacrum and the ilium.

How this list was compiled: Read 2026-09-26. OpenStax Anatomy and Physiology 2e, section 8.3 The Pelvic Girdle and Pelvis, https://openstax.org/books/anatomy-and-physiology-2e/pages/8-3-the-pelvic-girdle-and-pelvis : the hip bone formed by the ilium, ischium and pubis; the ilium as the fan-like superior region joined to the sacrum at the largely immobile sacroiliac joint; the iliac crest along the waistline; the anterior superior iliac spine at its rounded anterior end and the anterior inferior iliac spine below, both for thigh muscles; the iliac fossa on the internal upper ilium; the ischium as the posteroinferior region supporting the body when sitting, its ischial tuberosity carrying the weight when sitting; the pubis as the anterior portion, with body and superior and inferior rami, joining the opposite pubis at the pubic symphysis; the pelvis as the two hip bones, the sacrum and the coccyx. The ilium, pubis and ischium converging in the cup-shaped acetabulum on the lateral side, part of the hip joint; the obturator foramen as the large opening between the ischium and pubis. Licence: own work

The drawing: Drawn for this site on 2026-10-05 by script. The outline of the hip bone, its obturator foramen, the sacrum with its ridges and holes and the coccyx were read off a public domain plate: Henry Gray, Anatomy of the Human Body (20th US edition, 1918; Wikimedia Commons, public domain), fig. 241 'Male pelvis' (https://commons.wikimedia.org/wiki/File:Gray241.png). The right hip bone of the plate is used for both sides. The hip socket turned a little toward the viewer, the shorter coccyx, the tinted landmark areas, the hatching and the contour lines are our own. Licence: own drawing; outlines after a public domain plate

How it works

Label the structures of the pelvis from the front: the two hip bones with the sacrum and coccyx between them, the parts named on one side. Start with the 9 main parts, then every spine, hollow and joint.

Read the full guide

One hip bone, three parts

Each hip bone is the ilium, ischium and pubis fused together. The ilium is the broad wing, with the iliac crest along its top and the iliac spines at its front. The ischium is the lower back part, and the pubis runs to the front. All three meet at the acetabulum, the hip socket.

The ring

The two hip bones meet the sacrum at the sacroiliac joints behind and each other at the pubic symphysis in front. The coccyx hangs below the sacrum. The obturator foramen is the large hole between the pubis and the ischium.

You sit on the ischial tuberosities, and your hands rest on the iliac crests at your waist.

Questions and answers

What are the three bones of the hip bone?

The ilium, ischium and pubis. They fuse during the late teenage years into one hip bone and meet at the acetabulum.

What bones make up the pelvis?

Four: the right and left hip bones, the sacrum and the coccyx.

Where is the anterior superior iliac spine?

At the front end of the iliac crest, where you can feel a bony point at the front of the hip. Thigh muscles attach to it.