Anatomy of the Horse Pelvis

Overview

• Focus on: anatomy of the pelvis of the horse
• Comparison with other animal species

Structure of the Equine Pelvis

• Composition: Two hip bones meeting at the pelvic symphysis
• Development:
  • In young animals, hip bones articulate with cartilage allowing growth.
  • In adults, hip bones are fused.

Components of Hip Bone

• Three parts:
  1. Ilium
  2. Pubis
  3. Ischium
• Pelvic Symphysis: Ventrally unites pubis and ischium.
  • Cranial part: Pubic
  • Caudal part: Ischial

Ilium

• Forms dorsal cranial part of hip bone from acetabulum to sacrum.
• Divisions:
  • Cranial expanded wing (flat and broad)
  • Columnar body
• Landmarks:
  • Coxal tuberosity: Origin of internal abdominal muscle.
  • Sacral tuberosity and iliac crest: Boundary between the two tuberosities.
• Surfaces:
  • Lateral surface (gluteal surface): Area of origin for gluteal muscles.
  • Medial surface: Auricular surface for articulation with sacrum.
• Notches:
  • Greater sciatic notch: For the sciatic nerve.
  • Arcuate line: Marking on the ventral body border.

Pubis

• Shape: L-shaped with body and branches.
  • Branches: Acetabular and symphusial.
• Contributes to obturator foramen.
• Pectin of pubis: Cranial edge, important in horse.
• Iliopubic eminence: Ventral surface crossed by pubic groove leading to acetabulum.

Ischium

• Divisions:
  • Body
  • Caudal plate
  • Medial branch contributing to obturator foramen.
• Landmarks:
  • Sciatic spine: Projection where body of ischium meets ilium.
  • Ischial tuberosity: Origin for long thigh muscles.
  • Ischial arch: Formed by caudal borders of ischium.

Dorsal and Ventral Views

• Dorsal view highlights:
  • Ilium wings with tubercles.
  • Acetabulum and symphysis pelvis (pubic/ischael parts).
• Ventral view includes:
  • Auricular surface, iliopubic eminence, and obturator foramina.

Acetabulum

• Formed by ilium, pubis, and ischium.
• Fascia lunata: Smooth surface for femur head articulation.
• Acetabular notch: Opening supported by transverse acetabular ligament.
• Presence of accessory ligament in horses.

Comparative Anatomy

Ox Pelvis

• Similar structure: Two hip bones, three constituent bones.
• Notable differences:
  • Prominent gluteal line.
  • Straight iliac crest.
  • Acetabulum: Divided by cranioventral notch.

Camel Pelvis

• Similar structure to horses.
• Differences:
  • Smaller ischial blade compared to ox and horse.
  • Less developed projections.

Sheep Pelvis

• Similar structure with L-shaped pubis and obturator foramen.
• Differences:
  • Narrow acetabular notch and less prominent gluteal line.

Dog Pelvis

• Specific shape with similar components.
• Differences:
  • Small acetabulum surface for femur head.
  • Convex iliac crest.
  • Less defined sciatic spine and notches.

Summary

• Key features for comparative anatomy:

  • Acetabulum shape and divisions
  • Ischial tuberosity structure
  • Iliac wing orientation and crest shape.

• Next topic: Skeleton of the hind limb (os femur).