The Skeletal System Part 1

Overview of Bones

• Bones are classified as organs and are made up of various tissue types, primarily osseous connective tissue.
• Calcification gives bones their sturdy and rigid matrix.

Functions of Bones

• Support: Provides a structural framework for the body and protects soft organs.
• Protection: Shields vital organs, including the brain and spinal cord, from injury.
• Movement: Serves as levers for muscles, facilitating movement.
• Mineral Storage: Acts as a reservoir for minerals, notably calcium and phosphorus, containing over 90% of these reserves.
• Blood Cell Formation: Hematopoiesis takes place within the marrow cavities, specifically red bone marrow found in spongy bone.
• Energy Storage: Yellow marrow stores fat.

Bone Classification

• By Shape:

  • Long Bones: Longer than wide (e.g., humerus).
  • Short Bones: Cube-shaped (e.g., wrist and ankle bones).
  • Flat Bones: Thin and curved (e.g., sternum, skull bones).
  • Irregular Bones: Bones with complex shapes (e.g., vertebrae, hip bones).
  • Sesamoid (Round) Bones: Bones that form within tendons (e.g., patella).

• By Structure:

  • Axial Skeleton: Comprises bones of the skull, vertebral column, and rib cage.
  • Appendicular Skeleton: Includes bones of limbs, shoulder, and hips.

Bone Structure

• External Structure:

  • Epiphyses: Expanded ends of long bones with a compact bone exterior and spongy bone interior, covered in articular cartilage.
  • Diaphysis: Long tubular shaft of bones composed of compact bone surrounding the medullary cavity, containing yellow marrow.

• Internal Structure:

  • Spongy Bone: Contains red marrow for blood cell production.
  • Compact Bone: Dense and forms the outer layer of bones.
  • Medullary Cavity: Central cavity containing yellow marrow.
  • Epiphyseal Plate (“Growth Plate”): Found in children, facilitates bone growth.

Parts of a Long Bone

• Epiphysis: Distal and proximal ends.
• Diaphysis: Tubular shaft.
• Compact Bone: Outer layer.
• Spongy Bone: Interior.
• Articular Cartilage: Joint surfaces.
• Periosteum: Protective outer layer.
• Endosteum: Lining of the internal cavity.
• Medullary Cavity: Contains marrow (red and yellow).
• Trabeculae: Network of bone in spongy bone.

Structure of Short, Irregular, and Flat Bones

• Composed of thin plates of compact bone, covered by periosteum on the outside and endosteum on the inside.
• Lack diaphysis and epiphyses, with bone marrow situated between trabeculae.

Explore the intricate functions and structures of the skeletal system in this quiz. Learn about the composition of bones and their vital roles in supporting and protecting the body. Perfect for students in health sciences and rehabilitation studies.