The Human Skeleton
When babies are born they have about 270 bones. Then many of them fuse and an average adult has 206 bones.
Primary Functions of the Skeleton
Support and Shape: It provides the structural framework for your body, giving it shape and allowing you to stand upright.
Protection: It acts as a shield for your vital organs. For example, your skull protects your brain, and your rib cage protects your heart and lungs.
Movement: Bones provide attachment points for muscles. When muscles contract, they pull on the bones, acting as levers to create movement at the joints.
Blood Cell Production: The soft, spongy tissue inside many of your larger bones (called bone marrow) produces red blood cells, white blood cells, and platelets.
Mineral Storage: Bones act as a reservoir for essential minerals, particularly calcium and phosphorus, releasing them into the bloodstream as the body needs them.
The Two Main Divisions
The human skeleton is generally divided into two main parts:
1. The Axial Skeleton (80 bones) This forms the central axis of the body and focuses on protection and support.
The Skull: Protects the brain and forms the structure of the face.
The Vertebral Column (Spine): Protects the spinal cord and supports the head and torso.
The Thoracic Cage (Rib Cage): Includes the ribs and sternum (breastbone), protecting the heart and lungs.
2. The Appendicular Skeleton (126 bones) This consists of the limbs and the structures that attach them to the axial skeleton, focusing primarily on movement.
Pectoral Girdles (Shoulders): The collarbones (clavicles) and shoulder blades (scapulae).
Upper Limbs: The arms, wrists, and hands.
Pelvic Girdle (Pelvis): Connects the spine to the lower limbs and supports the organs of the lower abdomen.
Lower Limbs: The legs, ankles, and feet.
Quick Facts
Smallest Bone: The stapes (stirrup) located deep inside the middle ear. It's about the size of a grain of rice.
Largest Bone: The femur (thigh bone). It is the longest, heaviest, and strongest bone in the human body.
Most Bones: More than half of your body's bones are located in your hands (27 in each) and feet (26 in each).