Human Skeletal System

Basic Facts

• The adult human skeletal system typically consists of 206 bones.
• Bones are categorized into five groups, each with different functions and shapes.

Bone Groups

Long Bones

• Definition: They are long because they are much longer than they are wide.
• Structure: Consist of three sections - epiphysis, metaphysis, and diaphysis.
• Epiphysis: Contains spongy bones and red bone marrow, which synthesizes red blood cells.
• Metaphysis: Includes the epiphyseal plate responsible for bone growth.
• Diaphysis: A long, curved shaft containing compact bone.
• Functions: Support body weight and provide resistance to high loads.
• Examples: Clavicle, humerus, radius, ulna, femur, tibia, fibula, metacarpals (in fingers).

Short Bones

• Definition: Shaped like a cube, their length is equal to their width.
• Functions: Provide stability and support to other bones.
• Examples: Bones of the wrist (carpals) and ankles (tarsals).

Flat Bones

• Definition: Relatively thin with large surface area.
• Functions: Protect internal organs and serve for muscle attachments.
• Examples: Skull, ribs, sternum, scapula, pelvis.

Irregular Bones

• Definition: Have a unique shape that cannot be classified into the other categories.
• Functions: Protection and support.
• Examples: Maxilla (upper jaw), mandible (lower jaw), vertebrae (cervical and lumbar).

Sesamoid Bones

• Definition: Their shape is like that of a sesame seed.
• Functions: Grow within tendons.
• Example: Patella (kneecap), which is found in a tendon.

Conclusion

• The human skeletal system is composed of different types of bones, each with specific functions and structures.
• Understanding their differences is important for studying anatomy and physiology.