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Various bones of the human skeletal system. The axial skeleton , comprising the spine, chest and head, contains 80 bones. The appendicular skeleton , comprising the arms and legs, including the shoulder and pelvic girdles, contains 126 bones, bringing the total for the entire skeleton to 206 bones.
However, bones are not entirely made of calcium, but a mixture of chondroitin sulfate and hydroxyapatite, the latter making up 70% of a bone. Hydroxyapatite is in turn composed of 39.8% of calcium, 41.4% of oxygen, 18.5% of phosphorus, and 0.2% of hydrogen by mass. Chondroitin sulfate is a sugar made up primarily of oxygen and carbon. [citation ...
In the human body at birth, approximately 300 bones are present. Many of these fuse together during development, leaving a total of 206 separate bones in the adult, not counting numerous small sesamoid bones. [3] [4] The largest bone in the body is the femur or thigh-bone, and the smallest is the stapes in the middle ear.
The main elements that comprise the human body (including water) can be summarized as CHNOPS. Element Symbol percent mass percent atoms Oxygen O 65.0 24.0 Carbon C 18.5 12.0 Hydrogen H 9.5 62.0 Nitrogen N 2.6 1.1 Calcium Ca 1.3 0.22 Phosphorus P 0.6 0.22 Sulfur S 0.3 0.038 Potassium K 0.2 0.03 Sodium Na 0.2 0.037 Chlorine Cl 0.2 0.024 Magnesium Mg
The vertebral column is often used as a marker of human anatomy. This includes: At C1, base of the nose and the hard palate; At C2, the teeth of a closed mouth; At C3, the mandible and hyoid bone; At C4, the common carotid artery bifurcates. From C4–5, the thyroid cartilage [10] From C6–7, the cricoid cartilage [10]
A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. These bones form in tendons (the sheaths of tissue that connect bones to muscles) where a great deal of pressure is generated in a joint. The sesamoid bones protect tendons by helping them overcome compressive forces.
This is an accepted version of this page This is the latest accepted revision, reviewed on 24 February 2025. List of organ systems in the human body Part of a series of lists about Human anatomy General Features Regions Variations Movements Systems Structures Arteries Bones Eponymous Foramina Glands endocrine exocrine Lymphatic vessels Nerves Organs Systems Veins Muscles Abductors Adductors ...
A skeleton is the structural frame that supports the body of most animals.There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal frame to which the organs and soft tissues attach; and the hydroskeleton, a flexible internal structure supported by the hydrostatic pressure of body fluids.