Question

Compact bone is composed of ________. a.

1. trabeculae
2. compacted collagen
3. osteons
4. calcium phosphate only

Short answer

The correct answer is option (c).

Compact bone is composed of osteons.

Step-by-step solution

Osteons

• An osteoclast-rich tissue creates osteons, which are cylindrical vascular tunnels.
• The main structural component of a compact bone, or osteon, is made up of lamellae and Haversian canals.
• The osteon is made up of a central canal called the osteonic and concentric rings of matrix called lamellae.

Step: 1 Explanation for Correct answer

• Osteons or haversian systems that are compacted closely together make up compact bone.
• Blood arteries in the osteonic canals run parallel to the long axis of the bone. . Thus, the option c is correct.

Step: 2 Explanation for wrong answer

• Trabecular bone is a very porous, heterogeneous, and anisotropic substance that is present in the vertebral bodies and at the epiphyses of long bones. So, option a is wrong.
• Triple helix structure makes up the collagen protein. So, option b is wrong as well.
• Type I collagen makes up the majority of bone and is mineralized by calcium-phosphate crystals. Hence, option d is wrong too.