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Iliac crest

Iliac crest is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Iliac crest rather than just read about it. In short: The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis. Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS).

Iliac crest — main illustration
Iliac crest — illustration

Key takeaways

  • Iliac crest belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Iliac crest to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Iliac crest from memory before moving on to harder problems.

Reference excerpt

The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis.

Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (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. Palpable in its entire length, the crest is convex superiorly but is sinuously curved, being concave inward in front, concave outward behind. It is sigmoid in shape, such that viewed from above, the left iliac crest resembles an outstretched S, while the right iliac crest forms its mirror image. It is thinner at the center than at the extremities.

Development The iliac crest is derived from endochondral bone.

Function The external lip are attached the Tensor fasciae latae, 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 Transversus abdominis, Quadratus lumborum, Sacrospinalis, and Iliacus.

Abdominal external oblique muscle Abdominal internal oblique muscle Transversus abdominis muscle Quadratus lumborum muscle Erector spinae Iliocostalis pars lumborum Longissimus pars thoracis Latissimus dorsi Tensor fasciae latae Iliacus muscle Fascia lata Iliac fascia Transverse fascia

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 used in bone marrow transplantation. The iliac crest is also considered the best donor site for bone grafting 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. 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. Furthermore, said level is often referred to as the "intercristal line".

Additional images

See also

Apollo's belt Hip pointer

References This article incorporates text in the public domain from page 234 of the 20th edition of Gray's Anatomy (1918)

Bogduk, Nikolai; Endres, Stephen M. (2005). Clinical anatomy of the lumbar spine and sacrum (4th ed.). Elsevier Health Sciences. p. 106. ISBN 0-443-10119-1. Palastanga, Nigel; Field, Derek; Soames, Roger (2006). Anatomy and Human Movement: Structure and Function. Elsevier Health Sciences. ISBN 0-7506-8814-9. Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System (5th ed.). Thieme. ISBN 3-13-533305-1.

External links

Atlas image: back_bone30 at the University of Michigan Health System - "The Back, Posterior View" (#4)

Illustrations

Iliac crest illustration
Iliac crest illustration
Iliac crest: A fracture of the left iliac wing
A fracture of the left iliac wing
Iliac crest illustration
Iliac crest illustration

Worked examples

Example 1 — a first encounter with Iliac crest

Start with the simplest possible case. Write down what Iliac crest claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Iliac crest before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Iliac crest ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Iliac crest

In research
Iliac crest appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Iliac crest in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Iliac crest is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bones of the pelvis, Human anatomy, Ilium (bone), so understanding it makes those chapters shorter.
In everyday life
Look for Iliac crest outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Iliac crest in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Iliac crest means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Iliac crest out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Iliac crest in simple terms?

The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis. Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS).

Why does Iliac crest matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Iliac crest?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Iliac crest.

Tags

  • Bones of the pelvis
  • Human anatomy
  • Ilium (bone)

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