Human skeleton


Refers to the internal framework of the body.

It is composed of around 270 bones at birth.

The bone total decreases to around 206 bones by adulthood after some bones get fused together.

Bone mass in the skeleton reaches maximum density around age 21.

The human skeleton is divided into the axial skeleton and the appendicular skeleton.

The axial skeleton is formed by the vertebral column, the rib cage, the skull and other associated bones.

The appendicular skeleton, is attached to the axial skeleton, and is comprised of the shoulder girdle, the pelvic girdle and the bones of the upper and lower limbs.

The skeleton has six major functions; support, movement, protection, production of blood cells, storage of minerals, and endocrine regulation.

Differences between sexes in the morphology of the skull, dentition, long bones, and pelvis exist.

Female skeletal components tend to be smaller than corresponding male elements within a given population.

The human female pelvis is different from that of male pelvis to accommodate childbirth.

The axial skeleton has 80 bones formed by the vertebral column (32–34 bones), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).

The number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length.

The upright posture of humans is maintained by the axial skeleton, transmitting the weight from the head, the trunk, and the upper extremities down to the lower extremities at the hip joints.

Many ligaments and the erector spinae muscles support the bones of the spine.

The appendicular skeleton has 126 bones.

The appendicular skeleton is formed by the pectoral girdles, the upper limbs, the pelvic girdle or pelvis, and the lower limbs.

The appendicular skeleton functions are to make locomotion possible and to protect the major organs of digestion, excretion and reproduction.

It provides the framework which supports the body and maintains its shape.

The pelvis bones, with its associated ligaments and muscles provide a floor for the pelvic structures.

The rib cages, costal cartilages, and intercostal muscles, protect the lungs from collapse.

It helps to protect our many vital internal organs from being damaged.

The skull protects the brain.

The vertebrae protect the spinal cord.

The rib cage, spine, and sternum protect the lungs, heart and major blood vessels.

The joints between bones allow movement.

Some joints allow a wider range of movement than others.

Skeletal muscles power movement.

Skeletal muscles are attached to the skeleton at various sites on bones.

The nervous system coordinates muscles, bones, and joints to provide the principal mechanics for movement.

Bone density has reduced historically due to the change in our living habits.

It is the site of hematopoiesis.

Hematopoiesis occurs primarily in the marrow of the long bones such as the femur and tibia.

In adults, hematopoiesis occurs mainly in the pelvis, cranium, vertebrae, and sternum.


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