Iliac bone: Definition, Morphology and Function

Also called coxal (hip bone or pelvic bone) is a large bone, which is classified as irregular bone and is predominantly flat.

It has this classification because in its morphology it presents recesses, spines, cavities, ridges and holes.

Morphology of the iliac bone

It is an even bone, therefore they are two coxal bones located on each side of the body and together they make up the anterior wall and the sides of the pelvic cavity.

It is composed of three bones, the ilium, the ischium and the pubis , these bones are not the same in the young individual, but they are able to fuse when they are adults.

The acetabulum, the point at which the three bones meet, is located near the center of the surface of the bone at its outermost part.

These six bones, are arranged three on the right and three on the left, are primitive bones fused in adulthood and are located in the iliac bone as follows:

  • The ilium: Which has this name because it is compatible with the flank, is the broad and expanded upper portion that widens up the acetabulum .
  • The ischium: Is the strongest and lowest part of the bone located in the lower area of ​​the acetabulum, extends into a large tuberosity, and then curves forward and forms a large opening with the pubis called the obturator hole.
  • The pubis: It is located in the frontal part and extends from the acetabulum down, articulating in the middle line with the other bone in the opposite part and forming the anterior portion of the pelvis to offer a protective covering of the organs in the area Pubic

In this conformation of the coxal bones the following structures stand out:

  • Iliac crest : The iliac crest defines the superior sulcus of the wings of the ilium.
  • Obturator hole: The obturator hole is an opening that is observed in the pubis where the blood vessels and nerves pass.

Within the joints and ligaments we have:

Sacroiliac joints

These articulations join the auricular masks of the coxal with the auricular masks of the sacrum. They allow a certain movement for the opening of the pelvic space during childbirth.

The sacroiliac joints are reinforced by the anterior, posterior, and interosseous sacroiliac ligaments and iliolumbar ligaments.

And other ligaments that serve to stabilize this joint at a distance are the sacrospinous and sacrotuberous.

Symphysis of the pubis

This is a cartilaginous joint, amyrtarthrosis, that unites the two bones. It is reinforced by the ligaments: superior and inferior of the pubis and the inguinal ligament

Coxofemoral joint

This joint transmits the weight of the trunk to the lower extremities and is reinforced by 3 ligaments: iliofemoral, ischiofemoral and pubofemoral.

The coxofemoral joint has a labrum that extends the surface of the joint.

The two coxal bones are joined to the pubic symphysis and together with the sacrum and coccyx make up the skeletal component of the pelvis.

The iliac bone is connected to the sacrum, and is part of the axial skeleton, in the joint called sacroiliac.

Each of the iliac bones of the hip are connected to the corresponding femur, constituting the primary connection between the bones of the lower extremities and the skeleton by means of the hip joint.

Function of the iliac bone

The iliac bone as a whole, forms a flattened and irregular structure wider at the top and at the bottom a little less.

This structure is compatible with the weight of the upper part of the human body; head, back and upper extremities and offers support to the upper part, also provides structural integrity to the spine.

The iliac bone is important because together they form the pelvis, which is the structure responsible for connecting the legs with the torso. The pelvis also provides support and redistributes the standing weight of the human body.

In addition to offering this support, another function of the coxal bones is that they support the abdominal , pelvic and bladder viscera and reproductive organs and help protect these internal organs from impact and damage.

The pelvis has an important role in the anchoring of the legs, in addition to offering the insertion points to the muscles that mobilize the thigh.

Providing the necessary stabilization when the individual walks, runs and performs other activities while standing.

The iliac bone is usually used for autologous bone grafts in spine surgeries.

The shape of the iliac bone is morphologically different between men and women. This is associated with the reproductive function of women.