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Skeletal System. Skeletal System Overview. A newborn baby has 305 bones. As a human develops to the age of 25, some bones fuse together to obtain maximum strength. The average human skeleton has 206 bones. Largest bones – Thigh (Femur) and the Upper Arm (Humerus).
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Skeletal System Overview • A newborn baby has 305 bones. • As a human develops to the age of 25, some bones fuse together to obtain maximum strength. • The average human skeleton has 206 bones. • Largest bones – Thigh (Femur) and the Upper Arm (Humerus). • Smallest bones – Middle Ear (Maleus, Incus and Stapes). • All bones are living organs, which contain living (cells) and non-living (mineral) materials.
Functions of Bones • Bones have 5 major functions: Support –Provide support for tendons and ligaments and the framework for body shape. Protection – The cranium protects your brain, the ribs and sternum protect your internal organs such as heart and lungs. Movement – Bones work with muscles to produce movement. Muscles are attached to the skeleton and work by contracting (shortening) and pulling on bones. Storage – Bones are the site for storage and release of excess minerals. These are released as the body requires. Blood production – Some bones (ribs, vertebrae, humerus and femur) contain red bone marrow. This makes red cells, white cells and platelets for blood.
Cranium Mandible Scapula Clavicle Sternum Humerus Ribs Vertebrae Radius Pelvis Ulna Carpals Metacarpals Phalanges Femur Patella Fibula Tibia Tarsals Metatarsals Phalanges
Bone Classifications – Long Bones • Long bones consist of a long shaft covered by hard bone around a hollow centre which contains yellow marrow. • The two ends contain spongy bone and red marrow. • These bones are light but very strong, and are major weight-bearing bones of the body.
Bone Classifications – Short Bones • Short bones are chunky, compact bones that are strong and reinforced by thickening of the bone tissue. • They contain spongy bone and allow a variety of movements at joints.
Bone Classifications – Flat Bones • Flat bones are made up of two strong layers of compact bone, joined by a layer of spongy bone. • These bones give protection to organs beneath them and allow for large areas of muscle attachment.
Bone Classifications – Irregular Bones • Irregular bones are made up of a thin layer of compact bone containing a mass of spongy bone. • Irregular bones are reinforced where extra strength is needed.