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Anterior view of an adult human skeleton
Posterior view of an adult human skeleton
The human skeleton consists of both fused and individual bones supported and supplemented by ligaments, tendons, muscles and cartilage. It serves as a scaffold which supports organs, anchors muscles, and protects organs such as the brain, lungs and heart.
The biggest bone in the body is the femur in the thigh and the smallest is the stapes bone in the middle ear. Several factors contribute to the bone density and average mass of the human skeleton including; gender, race, hormonal factors, nutrition, physical activity and lifestyle ...view middle of the document...
The flat bones of the skull and the clavicles are formed from connective tissue in a process known as intramembranous ossification, and ossification of the mandible occurs in the fibrous membrane covering the outer surfaces of Meckel's cartilages. At birth, a newborn baby has over 300 bones, whereas on average an adult human has 206 bones (these numbers can vary slightly from individual to individual). The difference comes from a number of small bones that fuse together during growth, such as the sacrum and coccyx of the vertebral column.
See also: List of bones of the human skeleton
There are over 206 bones in the adult human skeleton, a number which varies between individuals and with age – newborn babies have over 270 bones some of which fuse together into a longitudinal axis, the axial skeleton, to which the appendicular skeleton is attached.
 Axial skeleton
Main article: Axial skeleton
The axial skeleton (80 bones) is formed by the vertebral column (26), the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones). The axial skeleton transmits the weight from the head, the trunk, and the upper extremities down to the lower extremities at the hip joints, and is therefore responsible for the upright position of the human body. Most of the body weight is located in back of the spinal column which therefore have the erectors spinae muscles and a large amount of ligaments attached to it resulting in the curved shape of the spine. The 366 skeletal muscles acting on the axial skeleton position the spine, allowing for big movements in the thoracic cage for breathing, and the head. Conclusive research cited by the American Society for Bone Mineral Research (ASBMR) demonstrates that weight-bearing exercise stimulates bone growth. Only the parts of the skeleton that are directly affected by the exercise will benefit. Non weight-bearing activity, including swimming and cycling, has no effect on bone growth.
 Appendicular skeleton
Main article: Appendicular skeleton
The appendicular skeleton (126 bones) is formed by the pectoral girdles (4), the upper limbs (60), the pelvic girdle (2), and the lower limbs (60). Their functions are to make locomotion possible and to protect the major organs of locomotion, digestion, excretion, and reproduction.
The skeleton serves six major functions.
The skeleton provides the framework which supports the body and maintains its shape. The pelvis and associated ligaments and muscles provide a floor for the pelvic structures. Without the ribs, costal cartilages, the intercostal muscles and the heart would collapse.
The joints between bones permit movement, some allowing a wider range of movement than others, e.g. the ball and socket joint allows a greater range of movement than the pivot joint at the neck. Movement is powered by skeletal muscles, which are attached to the...