The crest of the ilium (or iliac crest) is the superior border of the

wing of ilium The wing (ala) of ilium is the large expanded portion of the ilium, the bone which bounds the greater pelvis laterally. It presents for examination two surfaces—an external and an internal—a crest, and two borders—an anterior and a posteri ...

and the superiolateral margin of the

greater pelvis The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor. The pelvic cavity primarily contains the reproduct ...

Structure

The iliac crest stretches posteriorly from the

anterior superior iliac spine The anterior superior iliac spine (abbreviated: ASIS) is a bony projection of the iliac bone, and an important landmark of surface anatomy. It refers to the anterior extremity of the iliac crest of the pelvis. It provides attachment for the ing ...

(ASIS) to the

posterior superior iliac spine The posterior border of the ala, shorter than the anterior, also presents two projections separated by a notch, the posterior superior iliac spine and the posterior inferior iliac spine. The posterior superior iliac spine serves for the attachme ...

(PSIS). Behind the ASIS, it divides into an outer and inner lip separated by the intermediate zone. The outer lip bulges laterally into the

iliac tubercle The iliac tubercle is located approximately posterior to the anterior superior iliac spine on the iliac crest in humans. The transverse plane that includes each of the tubercles (one from the left iliac tubercle and one from the right iliac tube ...

. Platzer (2004), p 186

Palpable Palpation is the process of using one's hands to check the body, especially while perceiving/diagnosing a disease or illness. Usually performed by a health care practitioner, it is the process of feeling an object in or on the body to determin ...

in its entire length, the crest is convex superiorly but is sinuously curved, being concave inward in front, concave outward behind. Palastanga (2006), p 243 It is thinner at the center than at the extremities.

Development

The iliac crest is derived from

endochondral bone Endochondral ossification is one of the two essential processes during fetal development of the mammalian skeletal system by which bone tissue is produced. Unlike intramembranous ossification, the other process by which bone tissue is produced, c ...

Function

To the external lip are attached the ''

Tensor fasciae latae The tensor fasciae latae (or tensor fasciæ latæ or, formerly, tensor vaginae femoris) is a muscle of the thigh. Together with the gluteus maximus, it acts on the iliotibial band and is continuous with the iliotibial tract, which attaches to the ...

'', '' Obliquus externus abdominis'', and '' Latissimus dorsi'', and along its whole length the '' fascia lata''; to the intermediate line, the '' Obliquus internus abdominis''. To the internal lip, the ''

iliac fascia The iliac fascia, or Abernethy's fascia, is a fascia in the region of the ilium of the pelvis. It has the following connections: * ''laterally'', to the whole length of the inner lip of the iliac crest. * ''medially'', to the linea terminalis of ...

'', the ''

Transversus abdominis The transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral (front and side) abdominal wall which is deep to (layered below) t ...

'', Quadratus lumborum,

Sacrospinalis The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes (gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or sitt ...

, and ''

Iliacus The iliacus is a flat, triangular muscle which fills the iliac fossa. It forms the lateral portion of iliopsoas, providing flexion of the thigh and lower limb at the acetabulofemoral joint. Structure The iliacus arises from the iliac fossa on ...

''. * Abdominal external oblique muscle *

Abdominal internal oblique muscle The abdominal internal oblique muscle, also internal oblique muscle or interior oblique, is an abdominal muscle in the abdominal wall that lies below the external oblique muscle and just above the transverse abdominal muscle. Structure Its fiber ...

* ''Transversus abdominis'' muscle *

Quadratus lumborum muscle The quadratus lumborum muscle, informally called the ''QL'', is a paired muscle of the left and right posterior abdominal wall. It is the deepest abdominal muscle, and commonly referred to as a back muscle. Each is irregular and quadrilateral in sh ...

* Erector spinae **

Iliocostalis Iliocostalis muscle is the muscle immediately lateral to the longissimus that is the nearest to the furrow that separates the epaxial muscles from the hypaxial. It lies very deep to the fleshy portion of the serratus posterior muscle. It latera ...

pars lumborum **

Longissimus The longissimus ( la, the longest one) is the muscle lateral to the semispinalis muscles. It is the longest subdivision of the erector spinae muscles that extends forward into the transverse processes of the posterior cervical vertebrae. Structu ...

pars thoracisBogduk (2005), p 106 * Latissimus dorsi *

Iliacus muscle The iliacus is a flat, triangular muscle which fills the iliac fossa. It forms the lateral portion of iliopsoas, providing flexion of the thigh and lower limb at the acetabulofemoral joint. Structure The iliacus arises from the iliac fossa ...

* Fascia lata *

Iliac fascia The iliac fascia, or Abernethy's fascia, is a fascia in the region of the ilium of the pelvis. It has the following connections: * ''laterally'', to the whole length of the inner lip of the iliac crest. * ''medially'', to the linea terminalis of ...

Transverse fascia The transversalis fascia (or transverse fascia) is a thin aponeurotic membrane of the abdomen. It lies between the inner surface of the transverse abdominal muscle and the parietal peritoneum. It forms part of the general layer of fascia lining ...

Clinical significance

The iliac crest has a large amount of red bone marrow, and thus it is the site of bone marrow harvests (from both sides) to collect the

stem cells In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of ...

used in

bone marrow transplantation Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...

. The iliac crest is also considered the most ideal donor site for

bone grafting Bone grafting is a surgical procedure that replaces missing bone in order to repair bone fractures that are extremely complex, pose a significant health risk to the patient, or fail to heal properly. Some small or acute fractures can be cured wit ...

when a large quantity of bone is needed. For example, oral and maxillofacial surgeons will often use iliac crest bone to fill in large osseous defects of the oral cavity caused by severe periodontal disease, excess bone resorption following tooth loss, trauma, or congenital defects including alveolar clefts.Rose, Louis F.. Periodontics: Medicine, Surgery and Implants. Mosby, 072004. 26.2.2.3 The top of the iliac crests also marks the level of the fourth lumbar vertebral body (L4), above or below which lumbar puncture may be performed.

Additional images

File:Iliac crest.PNG, Muscles connecting the upper extremity to the vertebral column. Left iliac crest is labeled in red. File:Gray237.png, Plan of ossification of the hip bone. File:Gray395.png, The Obliquus internus abdominis. File:Gray430.png, Muscles of the iliac and anterior femoral regions. File:Gray1124.png, The relations of the kidneys from behind. File:Orientation.PNG, Iliac crest labeled at center right. File:Slide7w.JPG, Iliac crest

References

* * *

External links

* - "Superficial muscles of the gluteal region and posterior thigh." * - "Anterior Abdominal Wall: Osteology and Surface Anatomy " * - "The Back, Posterior View" (#4)
Diagram at emedx.com

Diagram at nih.gov
{{Authority control Human anatomy Bones of the pelvis Ilium (bone)