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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.
In most terrestrial vertebrates (except snakes, legless lizards and caecillians), the appendicular skeleton and the associated skeletal muscles are the predominant locomotive structures. There are 126 bones in the human appendicular skeleton, includes the skeletal elements within the shoulder and pelvic girdles, upper and lower limbs, and hands ...
Movement is powered by skeletal muscles, which are attached to the skeleton at various sites on bones. Muscles, bones, and joints provide the principal mechanics for movement, all coordinated by the nervous system. It is believed that the reduction of human bone density in prehistoric times reduced the agility and dexterity of human movement.
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.
The other primary skeletal component of height are the vertebrae and skull. The outside of the bone consists of a layer of connective tissue called the periosteum . Additionally, the outer shell of the long bone is compact bone , then a deeper layer of cancellous bone (spongy bone) which contains in the medullary cavity the bone marrow .
In other animals, the vertebrae take the same regional names except for the coccygeal – in animals with tails, the separate vertebrae are usually called the caudal vertebrae. [19] Because of the different types of locomotion and support needed between the aquatic and other vertebrates, the vertebrae between them show the most variation ...
A true endoskeleton is derived from mesodermal tissue. In three phyla of animals, Chordata, Echinodermata and Porifera (), endoskeletons of various complexity are found.An endoskeleton may function purely for structural support (as in the case of Porifera), but often also serves as an attachment site for muscles and a mechanism for transmitting muscular forces as in chordates and echinoderms ...
The skeletal portion of the system serves as the main storage system for calcium and phosphorus and contains critical components of the hematopoietic system. [3] This system describes how bones are connected to other bones and muscle fibers via connective tissue such as tendons and ligaments. The bones provide stability to the body.