Lecture: Bone Model Structures

Overview

• Discuss the different structures to identify on a bone model, focusing on membranes, compact bone structures, and blood supply.

Membranes

Periosteum

• Location: Lines external surface of bone.
• Appearance: Whitish gray area on the model.
• Structure: Has white extensions called Perforating fibers that adhere the periosteum to compact bone.

Endosteum

• Location: Lines every internal surface of bone, including:
  • Canals
  • Spongy bone cavities
• Appearance: Gray shaded area on the model.

Compact Bone Structures

Osteon (Haversian System)

• Definition: Structural and functional unit of bone.
• Structure: Consists of concentric rings.
  • Central Canal (Haversian Canal): Central channel for nutrient supply and nerves.
  • Lamellae: Rings around the central canal.
  • Types of Lamellae:
    • Concentric Lamellae: Make up the osteon.
    • Interstitial Lamellae: Incomplete lamellae between osteons.
    • Circumferential Lamellae: Run along the entire circumference of the bone.

Lacunae

• Definition: Cavities where osteocytes reside.
• Appearance: Shown as small holes, white circle areas, or dark brown ovals in the lamellae.

Canaliculi

• Function: Tiny canals that connect lacunae, allowing communication between osteocytes.
• Appearance: Hair-like extensions from lacunae.

Bone Canals

Perforating Canals (Volkmann's Canals)

• Structure: Run horizontally through the bone.
• Relation to Perforating Fibers: Run in the same direction.

Central (Haversian) Canals

• Structure: Run vertically along the bone's long axis.
• Function: Carry blood supply and vessels.

Spongy Bone

Trabeculae

• Description: Bone spicules extending within the spongy bone.
• Lining: Endosteum lines all spaces within trabeculae.

Bone Marrow

• Location: Found in the medullary cavity and within the trabeculae.

Key Points

• Blood supply is a critical aspect, running through the central and perforating canals.
• Bone remodeling involves communication through canaliculi.
• The medullary cavity, not shown here, contains bone marrow.