Anatomy And Physiology

Human Skeleton 101

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Welcome to the human skeleton 101. I will go over some things you may have forgotten from science class about the human skeleton. The human skeleton consists of both fused and individual bones and those are divided into two categories, Axial and Appendicular skeleton.  The skeleton is responsible for around 14% of the total body weight, and half of the weight is water. The biggest bone is the Femur in the upper leg and the smallest is the stapes bone in the middle ear.

At birth, a human child has over 270 bones in their bodies, but a human adult has on average 206 bones that make up the skeleton. The reason for the change is fusion, which happen in the sacrum and coccyx. When a child reaches skeletal maturity (18 to 25 years old), all the cartilage is replaced by bones and the fusion is complete. Bones are rigid organs that move, support, and protect various organs of the body. Bone tissue is a type of dense connective tissue that is lightweight, yet strong and hard. There are five types of bones in the human skeleton: long, short, flat, irregular, and sesamoid. Almost all bones contain bone marrow, which at birth are filled exclusively with red marrow. As we age it is replaced with yellow, or fatty marrow.

The axial skeleton consists of 80 bones and is responsible for the upright position of the human body.  It takes weight from the head, trunk, and upper body and transmits it to the lower part of the body. The appenducular skeleton consists of 126 bones and is what makes movement possible.  The skeleton has six major functions which include, support, movement, protection, blood cell production, storage, and endocrine regulation.

There are sex based differences between male and female human skeletons. The most noticeable is the pelvis, which is flatter, larger, and more rounded in females. Females also have narrower rib cages, smaller teeth, less angular mandibles, less pronounced facial features, rounded shoulder blades and the carrying angle of the forearm is more pronounced. Males may have slightly thicker and longer limbs and digit bones (hand and feet bones).

The most common disorder affecting the skeleton is osteoporosis. This is a disease of bone which weakens the bone and can lead to an increased risk of fracture. Osteoporosis is most common in women after menopause but can also occur in postmenopausal females and men, but this is usually in the presence of hormonal disorders, other chronic diseases, medications, or smoking.  Osteoporosis can be prevented by having a good source of calcium and vitamin D, and with lifestyle advice and medication. It can be treated with biphosphonates  and various other medical treatment.

Wikipedia,, wiki/bones

Wikipedia,, wiki/bones

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