Interosseous border

The fibula is described with 3 surfaces and 5 borders (but these numbers vary between species):

• Interosseous border on the medial surface for attachment of interosseous membrane. In carnivores, the interosseous border is fused with the cranial border.
• Medial border (only present in proximal half of fibula in carnivores)
• Lateral border(only present in proximal half of fibula in carnivores)
• Cranial border
• Caudal border
• Medial surface that faces the tibia.
• Lateral surface
• Caudal surface, between medial and lateral border.