Cortical bone

Definition

Cortical bone, also known as compact bone, is the dense and hard outer layer of bone that provides strength and support. It forms the outer shell of all bones and is critical for protecting inner structures, providing mechanical support, and facilitating movement through its interaction with muscles.

5 Must Know Facts For Your Next Test

1. Cortical bone makes up about 80% of the total bone mass in the human body, providing rigidity and strength necessary for weight-bearing activities.
2. The thickness of cortical bone can vary significantly depending on the location in the body, with areas subject to greater stress having thicker cortical layers.
3. Cortical bone has a low porosity, which means it has fewer spaces or holes compared to trabecular bone, making it dense and strong.
4. This type of bone is rich in collagen fibers and minerals such as calcium phosphate, which contribute to its hardness and ability to withstand compressive forces.
5. Cortical bone plays a vital role in protecting the internal structures of bones, including marrow, blood vessels, and nerves, while also facilitating the attachment of muscles.

Review Questions

• How does the structure of cortical bone contribute to its function within the skeletal system?
  • The structure of cortical bone is dense and organized into cylindrical units called osteons, which provide strength and resilience under stress. This compact nature allows it to withstand substantial forces during activities like walking or lifting. The high mineral content also contributes to its rigidity, making cortical bone essential for protecting internal structures and supporting overall skeletal integrity.
• What differences exist between cortical bone and trabecular bone in terms of their roles in the skeletal system?
  • Cortical bone is dense and forms the outer layer of bones, providing strength and support, especially in weight-bearing areas. In contrast, trabecular bone is lighter and has a spongy structure that allows for shock absorption and facilitates metabolic activities like blood cell production in the marrow. Together, these two types of bone work synergistically to maintain overall skeletal health by balancing strength with lightness.
• Evaluate how factors such as age and physical activity influence the characteristics and health of cortical bone over a lifetime.
  • As individuals age, there is often a decrease in bone density due to reduced calcium absorption and hormonal changes, leading to thinner cortical bone. Additionally, physical activity plays a crucial role in maintaining cortical thickness; weight-bearing exercises stimulate bone remodeling processes that strengthen cortical bone. Thus, a proactive approach to exercise can help mitigate age-related declines in cortical bone density, promoting better skeletal health throughout life.

Related terms

Trabecular Bone: Also called cancellous bone, trabecular bone is the spongy inner layer of bone that is lighter and provides structural support while reducing the overall weight of the skeleton.

Osteon: The basic structural unit of cortical bone, osteons are cylindrical structures that consist of concentric layers of mineralized matrix and form a canal that houses blood vessels and nerves.

Bone Remodeling: A continuous process where old bone tissue is replaced by new bone tissue, which is crucial for maintaining bone strength and integrity throughout life.