Compact bone

Definition

Compact bone, also known as cortical bone, is the dense and solid outer layer of bone tissue that provides structural support and protection. It makes up approximately 80% of the total bone mass in the human body.

5 Must Know Facts For Your Next Test

1. Compact bone is composed of tightly packed osteons or Haversian systems, which are cylindrical structures that run parallel to the length of the bone.
2. It has a high resistance to bending and torsion due to its dense structure.
3. Blood vessels and nerves are housed within central (Haversian) canals in compact bone.
4. Compact bone surrounds spongy (cancellous) bone, providing a protective shell around it.
5. The periosteum, a fibrous membrane, covers the outer surface of compact bone and contains cells involved in growth and repair.

Review Questions

• What structural units make up compact bone?
• How does compact bone contribute to the strength and durability of bones?
• What role do central (Haversian) canals play in compact bone?

Related terms

Spongy Bone:

Also known as cancellous or trabecular bone, it is a porous inner layer found at the ends of long bones and within vertebrae.

Osteon: A cylindrical structure that forms the functional unit of compact bone, consisting of concentric lamellae surrounding a central canal.

Periosteum: A dense fibrous membrane covering the outer surface of bones except at their extremities where joints occur.