Osteology of the Hip Bone

Introduction

• Hip Bone: Also known as the innominate bone, irregular in shape.
• Components:
  • Dorsal component: Ilium
  • Ventral components: Ischium and Pubis
  • All components join at the acetabulum.

Acetabulum

• Function: Forms a ball and socket joint.
• Structure:
  • Initially contains tri-radiate cartilage, later ossified by secondary ossification.
  • Contribution: Pubis (1/5), Ilium and Ischium (2/5 each).

Anatomical Position & Orientation

• Ilium is dorsal, Pubis is anterior, Ischium is inferior.
• Forms part of the pelvis with the sacrum posteriorly.

Side Determination

• Acetabulum faces laterally.
• Obturator Foramen: Present in the lower expanded part, not upper.
• Medial Surface: Articulates with sacrum; lateral surface forms hip joint.
• Correct Orientation: Acetabulum faces outward; obturator foramen is lower.

Pelvis Formation

• Components: Two hip bones, sacrum.
• Function: Joint posteriorly with the sacrum, anteriorly with opposite hip bone via pubic symphysis.
• Anatomical Positioning:
  • ASIS and Pubic Tubercle in one coronal plane.
  • Symphyseal Surface in median plane.
  • Upper border of Pubic Symphysis and Iliac Spine in same horizontal plane.

Ilium Features

• Borders: Anterior, Posterior, Medial
• Surfaces:
  • Gluteal Surface: Lateral
  • Iliac Fossa: Above medial border
  • Sacro-pelvic Surface: Below medial border

Gluteal Lines

• Lines: Inferior (Anterior), Middle, Posterior
• Divide gluteal surface into compartments.

Sacro-pelvic Surface

• Divisions: Iliac Tuberosity, Auricular Area (synovial joint with sacrum), Pelvic Area

Pubis Features

• Structure: Body, Superior, and Inferior Ramus
• Landmarks:
  • Pubic Crest
  • Pubic Tubercle
• Surfaces: Anterior, Pelvic, Symphyseal

Ramus Features

• Borders: Pectinial Line, Obturator Crest
• Surfaces: Pectinial, Pelvic, Obturator

Ischium Features

• Structure: Body, Ramus
• Borders: Anterior, Posterior, Lateral
• Surfaces: Femoral, Pelvic, Dorsal

Notches and Ligaments

• Greater and Lesser Sciatic Notch: Present in dry bones.
• Converted to foramens by Sacro-tuberous and Sacro-spinous ligaments.

Summary

• Key Points:
  • Side determination using acetabulum and obturator foramen.
  • Anatomical positioning of hip bone as part of the pelvis.
  • Recognition of important bony landmarks on ilium, ischium, and pubis.