Skeletal System: Classification and Anatomy

Classification of Bones

• Bones classified by location, shape, function, structure, and development type.
• Two primary classifications: axial (central body axis) and appendicular (limbs and girdles).

Axial Skeleton

• Comprises bones along the body’s midline, supporting the head, neck, and trunk.

Appendicular Skeleton

• Includes bones of the limbs (appendages) and girdles connecting them to the axial skeleton.
• Girdles are composed of pectoral (shoulder) and pelvic (hip) structures, aiding in muscle attachment.

Scapula Functionality

• Dorsally positioned scapula provides extensive movement, enabling arm brachiation.
• Ball-and-socket joint structure allows for a wide range of motion, with potential issues arising from arthritis.

Human Locomotion

• Human body adapted for endurance in long-distance running.
• Plantigrade locomotion means entire foot contacts the ground, increasing friction during movement.

Types of Bones

• Long bones: Longer than wide, with distinct ends (proximal and distal) and a central shaft.
• Short bones: Cube-like, with equal length sides, providing stability.
• Irregular bones: Do not fit into the above categories; examples include vertebrae, sphenoid, and pelvis.
• Pneumatic bones: Feature air-filled cavities (sinuses), aiding in weight reduction and vocal resonance.

Bone Functions

• Provide structural support for organs and protect vital systems (brain, viscera, spinal cord).
• Facilitate movement through attachment to skeletal muscles.

Mineral Storage

• Bones store and release minerals like phosphorus and calcium, regulated by hormones (PTH and calcitonin).
• Bone health is linked to cardiovascular health.

Hematopoiesis

• Blood cell formation occurs in bone marrow, predominantly in flat bones during adulthood, while all bones contribute in juveniles.

Triglyceride Storage

• With aging, red marrow is replaced by yellow marrow (fat storage).

Bone Structures

• Compact bone: Organized structure with concentric rings for strength.
• Spongy bone: Unorganized structure composed of trabeculae, housing blood supply.

Hormonal Regulation of Calcium

• Parathyroid hormone (PTH): Released from the parathyroid gland, increases blood calcium levels by promoting bone resorption.
• Calcitonin: Produced in the thyroid gland, lowers blood calcium levels by promoting bone formation.

Bone Development

• Cartilaginous bones: Develop via hyaline cartilage models, with elongation through endochondral ossification; typical of long bones.
• Membranous bones: Formed from fibrous membranes replaced by bone, through intramembranous ossification; characteristic of flat bones.

This quiz explores the classification and anatomy of the skeletal system. It covers various terms related to bone classification, including axial and appendicular skeletons, as well as the significance of girdles. Enhance your understanding of skeletal structures and their functions.