reviews bone classifications with their associated features, functions, and examples. The patellae (singular = patella) are the only sesamoid bones found in common with every person. Sesamoid bones vary in number and placement from person to person but are typically found in tendons associated with the feet, hands, and knees. The sesamoid bones protect tendons by helping them overcome compressive forces. 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. Sesamoid BonesĪ sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. Many facial bones, particularly the ones containing sinuses, are classified as irregular bones. These bones tend to have more complex shapes, like the vertebrae that support the spinal cord and protect it from compressive forces.
Irregular BonesĪn irregular bone is one that does not have any easily characterized shape and therefore does not fit any other classification. Flat bones serve as points of attachment for muscles and often protect internal organs. Examples include the cranial (skull) bones, the scapulae (shoulder blades), the sternum (breastbone), and the ribs. The term “ flat bone” is somewhat of a misnomer because, although a flat bone is typically thin, it is also often curved. Short bones provide stability and support as well as some limited motion. The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short BonesĪ short bone is one that is cube-like in shape, being approximately equal in length, width, and thickness. Long bones function as levers they move when muscles contract. Long bones are found in the arms (humerus, ulna, radius) and legs (femur, tibia, fibula), as well as in the fingers (metacarpals, phalanges) and toes (metatarsals, phalanges). Keep in mind, however, that the term describes the shape of a bone, not its size. Their shapes and their functions are related such that each categorical shape of bone has a distinct function.Ī long bone is one that is cylindrical in shape, being longer than it is wide. The 206 bones that compose the adult skeleton are divided into five categories based on their shapes ( ). Describe the function of each category of bones.Classify bones according to their shapes.By the end of this section, you will be able to:
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