Hip Bone

Introduction

Bones of the pelvic girdle

Normal PA radiograph of bilateral hips

Illustration of the bony hip joint anatomy

Bony landmarks of the ilium

Bony anatomy of the pubis

Bony anatomy of the ischium

Illustration of the greater and lesser sciatic foramen

Nomenclature

• Hip Bone
• Also called innominate bones, pelvic bones

Composition

• Composed of
  • Ischium
  • Ilium
  • Pubis
• Pre-puberty these bones are anatomically distinct
  • Triradiate cartilage separates them
  • Fusion begins at age 15-17

Articulations

• Sacroiliac joint: articulation with the sacrum.
• Pubic symphysis: articulation between the left and right hip bones.
• Hip joint: articulation with the head of femur.

Acetabulum

• Cup-shaped socket formed by the ilium, pubis and ischium
• Acetabulum means 'vinegar cup' in Latin

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Ilium

General

• Widest, largest of 3 hip bones
• Located superiorly
• Forms the superior part of the acetabulum (acetabular roof)

Iliac Wing (ala)

• Inner surface
  • Concave shape
  • Iliac fossa (origin of Iliacus)
• External surface (gluteal)
  • Convex shape
  • Attachments to the gluteal muscles

Iliac Crest

• Superior margin of the wing is thickened
• Extends from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS)

Greater Sciatic Notch

• On posterior aspect of the ilium

Anterior Superior Iliac Spine

• Needs to be updated

Posterior Superior Iliac Spine

• Needs to be updated

Anterior Inferior Iliac Spine

• Commonly referred to as AIIS
• Attachments: Iliacus, Rectus Femoris
• Clinical significance: avulsion fractures and apophysitis in pediatric patients

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Pubis

General Description

• Anterior portion of the hip bone
• Consists of body, superior pubic ramus, inferior pubic ramus

Pubic body

• Located medially, forms pubic symphysis when articulating with the opposite pubic body
• Superior aspect marked by pubic crest (round thickening)
• Extends laterally as the pubic tubercle

Superior Pubic Ramus

• Extends laterally from the body to help form acetabulum

Inferior pubic ramus

• Projects towards the ischium

Obturator Foramen

• Formed by the superior and inferior pubic rami (and part of the ischium)
• Contents: Obturator Nerve, Obturator Artery, Obturator Vein
• Variation: larger and more oval in males, whereas it is smaller and more triangular in females
• Clinical relevance: uncommonly, an obturator hernia can pass through the foramen and cause bowel obstruction

Obturator Crest

• Anterior border of the superior pubic ramus
• Forms part of the circonfrence of the obturator foramen superiorly, affords attachment to the obturator membrane
• Extends from the pubic tubercle to the acetabular notch

Iliopectineal Eminence

• Also known as the iliopubic eminence
• Raised area that marks the union between the ilium and superior pubic ramis
• Contributes to the linea terminalis
• Insertion site for Psoas Minor
• Attachment site for Pubofemoral Ligament, Iliopsoas Fascia

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The anatomy of the hip region, including the head, femoral neck, greater trochanter, and lesser trochanter of the proximal femur, and the acetabulum, ilium, ischium, and pubis of the os coxae (pelvic bone)

Ischium

General Description

• Forms the posterior-inferior part of the hip bone
• Composed of a body, inferior and superior ramus

Inferior ischial ramus

• Combines with the inferior pubic ramus forming the ischiopubic ramus
• which encloses part of the obturator foramen

Ischial Tuberosity

• Posteriorinferior aspect of the ischium
• These tuberosities bear our weight when sitting or falling
• Muscle attachments: semitendinosus, semimembranosus, long head of biceps femoris

Ischial Spine

• Posteromedial projection of bone superior to the ramus

Sacrospinous Ligament

• Attachments: ischial spine to the sacrum
• Creates greater sciatic foramen: transmits the sciatic nerve to lower limb

Sacrotuberous Ligament

• Attachments: sacrum to ischial tuberosity
• Forms the lesser sciatic foramen

Lesser Sciatic Notch

• Smooth, coated with cartilage
• Ridges for the obturator internus
• Converted into the lesser sciatic foramen by the sacrotuberous and sacrospinous ligaments

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Clinical Significance

General

• Hip Dislocation

Pediatric

• Ischial Tuberosity Avulsion Fracture

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See Also

• Hip Pain Main
• Hip Anatomy Main
• Physical Exam Hip

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