Skeletal System Overview

Functions of the Skeletal System

• Provides support and structure for the body
• Protects internal organs, such as the brain, heart, and lungs
• Acts as a attachment site for muscles, allowing for movement
• Produces blood cells through bone marrow
• Stores minerals such as calcium and phosphorus

Types of Bones

• Long bones: longer than they are wide, e.g. femur (thigh bone)
• Short bones: approximately equal in length and width, e.g. carpals (wrist bones)
• Flat bones: thin and flat, e.g. ribs and sternum
• Irregular bones: do not fit into any other category, e.g. vertebrae
• Sesamoid bones: small, rounded bones embedded within tendons, e.g. patella (kneecap)

Bone Tissue

• Compact bone: dense, compact tissue found in the shafts of long bones
• Cancellous bone: spongy, porous tissue found in the ends of long bones and interior of flat bones
• Periosteum: outer layer of bone, covering the surface
• Endosteum: inner layer of bone, lining the marrow cavity

Skeletal System Divisions

• Axial skeleton: bones of the skull, spine, ribs, and sternum
• Appendicular skeleton: bones of the upper and lower limbs, pelvis, and shoulder girdle

Joints

• Synovial joints: freely movable joints, e.g. shoulder and elbow
• Cartilaginous joints: joints connected by cartilage, e.g. spine
• Fibrous joints: joints connected by fibrous tissue, e.g. skull bones

Bone Development and Growth

• Ossification: process of bone formation
• Endochondral ossification: process of bone formation from cartilage models
• Intramembranous ossification: process of bone formation from mesenchymal tissue