Introduction to Human Anatomy Part II: The Skeleton

Appendicular Skeleton

• The main role of the appendicular skeleton is to facilitate movement and support the body's appendages (limbs).

Axial Skeleton

• The axial skeleton mainly protects the central nervous system, including the brain and spinal cord.

Skeletal System

• The primary function of the skeletal system is to provide support, protection, and movement for the body.

Bone Structure

• Bone strength is contributed by the combination of organic and inorganic components.
• Compact bones are dense and tough, making up 80% of the skeleton's weight.
• Cancellous (spongy) bones are lightweight and porous, composed mainly of adipose cells.
• Compact bones appear as solid masses.
• Flat bones are thin and composed of two nearly parallel plates of compact bone enclosing a layer of spongy bone.

Bone Marrow

• Red bone marrow manufactures blood cells.
• At birth, the marrow of all bones is red and functional, gradually becoming inactive in certain bones with age.

Other Bone Types

• Irregular bones cannot be categorized into any specific type, varying in amounts of spongy and compact bone.
• Sesamoid bones develop in certain tendons that cross the ends of long bones in the limbs, protecting tendons from friction and wear.

Bone Cavities

• Bone marrow occupies the marrow cavity in long and short bones.