Focus on two types of bone: compact (lamellar) bone and spongy bone.
Compact Bone (Lamellar Bone)
Osteon (Haversian System)
Structure: Concentric circles called lamellae.
Composition: Dominated by collagen fibers running in alternate directions to resist stress and twisting.
Central Canal: Contains blood vessels and nerves.
Canals
Volkmann's (Perforating) Canals: Run perpendicular (90 degrees), connecting osteons to the circulatory system, endosteum, and periosteum.
Lacunae and Canaliculi
Lacunae: Small cavities where osteocytes reside.
Canaliculi: Hair-like connections formed by gap junctions between osteocytes, allowing nutrient and waste exchange.
Types of Lamellae
Circumferential Lamellae: Located at the perimeter of the compact bone, just deep to periosteum and superficial to endosteum.
Interstitial Lamellae: Found between osteons, indicates areas where osteons have been broken down.
Spongy Bone (Cancellous Bone)
Trabeculae
Structure: Appears disorganized but aligns along stress points.
Lamellae Arrangement: Irregularly arranged, unlike in compact bone.
Canaliculi: Present for osteocyte connections.
Nutrient and Blood Supply
Nutrient Foramen: Small openings in the diaphysis that allow passage of blood vessels and nerves into the bone structure.
Conclusion
Both compact and spongy bones have mechanisms to facilitate nutrient exchange and structural integrity, albeit through different arrangements and structures.