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The skeleton changes composition over a lifespan. Early in gestation, a fetus has no hard skeleton - bones form gradually during nine months in the womb. When a baby is born it has more bones than it will as an adult On average, an adult human has 206 bones in their skeleton (the number can vary slightly from individual to individual), but a baby is born with approximately 270. The difference comes from a number of small bones that fuse together during growth. These include the bones in the skull and the spine. The sacrum (the bone at the base of the spine) consists of six bones which are separated at birth but fuse together into a solid structure in later years.

There are 6 bones (three on each side) in the middle ear that articulate only with themselves, and one bone, the hyoid bone, which does not touch any other bones in the body.

The longest bone in the body is the femur and the smallest is the stapes bone in the middle ear.

1 Function

The skeleton functions not only as the support for the body but also in haematopoiesis, the manufacture of blood cells that takes place in bone marrowBone marrow is the tissue comprising the center of large bones. It is the place where new blood cells are produced. Bone marrow contains stem cells which produce three types of blood cells: leukocytes, red blood cells, and platelets. Long bones" are tubul. It is also necessary for protection of vital organs and is needed by the muscles for movement.

2 Gender differences

There are small differences between the male and female human skeletons. Men tend to have slightly thicker and longer limb bones while women tend to have larger pelvic bones in relation to body size.

According to the Bible, AdamThis article is about the biblical Adam and Eve. For other uses, see Adam (disambiguation) and Eve (disambiguation According to the Book of Genesis of the Bible and to the Quran, Adam "Dust; mankind", Standard Hebrew Adam Tiberian Hebrew m Arabic dam was had his lower rib removed to make Eve; this has given rise to a (mistaken) belief that men have one less rib than women.

The lower rib can actually regenerate if the periosteumPeriosteum is the connective tissue surrounding bone. As opposed to bone itself, it has nosiceptive nerve endings, making it very sensitive to manipulation. is left intact. Within the periosteum are cells, which can generate new bone. It is especially effective in young people. Thoracic surgeons are well aware of the regenerating ability of lower rib bones. Intercostal muscles attached to the lower rib also provide it with a good supply of blood required for regeneration.

3 Organization

One way to group the bones of the human skeleton is to divide them into two groups, namely the axial skeletonThe axial skeleton is the bones constituting the head and trunk of a vertebrate body. and the appendicular skeletonThe Appendicular Skeleton is the part of the skeleton that includes the pectoral girdle and the pelvic girdle and the upper and lower limbs.. The axial skeleton consists of bones in the midline and includes all the bones of the head and neck, the vertebrae, ribs and sternum. The appendicular skeleton consists of the clavicles, scapulae, bones of the upper limb, bones of the pelvis and bones of the lower limb.

The bones of the human skeleton are structurally and in many taxonomies organized as those of the:

• skull
• middle ear
• throat
• shoulder girdle
• thorax
• vertebra
• arms
• hands
• pelvis
• legs
• feet