Usually adults have 206 bones, including skull, trunk and limbs. However, we China and Japanese only have 204 bones.
This is because our fifth finger bone has only two joints, while Europeans and Americans have three joints, so China people have two fewer joints than Europeans and Americans. Children have more bones than adults, generally 2 17 or 2 18.
In the process of evolution, the protective function and supporting function of bones are combined with each other. For example, the exoskeleton of invertebrates is both a support system and a protection system. The main function of vertebrate bones is support, and the protective function gives way to the skin.
The skeleton of the human body plays a role in supporting the body and is a part of the human motion system. Adults have 206 bones, usually connected by joints and ligaments. Except 6 ossicles belonging to sensory organs, they can be divided into 23 skulls, 5 1 trunk bones and 126 limbs bones.
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When judging age from bones, in order to improve the accuracy of the results, many methods are often used to verify each other. In view of the fact that nutrition, health, geographical environment, gender and many other factors will affect the shape of bones, many skeletal features, such as the appearance of ossification center and the healing of epiphysis, will change regularly with age.
For example, at the age of 30~40, the ossification center of costal cartilage increases, and the sternal stalk and sternal body heal. At the age of 40~50, the sternum and xiphoid process healed, and the larynx and costal cartilage began to solidify. Over the age of 60, the whole body cartilage will ossify.
For the age identification of adult bones, it is common to observe and compare the morphological changes of bones. In childhood, there are many organic components in bone tissue, which make bones have high toughness and low hardness.
In adulthood, the proportion of inorganic substances gradually increased, accounting for about 70%. At this time, the bones are not only hard, but also elastic and tough. In old age, inorganic components further increase and bones become more brittle. At the same time, under the action of bone hyperplasia and absorption, the shape of bone has also changed accordingly.
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