Bones are highly specialised connective tissue composed of an inorganic mineral component and a dense organic matrix. The skeletal system comprises bone segments that vary in size, shape, and density. Their mechanical strength and hardness distinguish them.
Long bones feature an inner medullary cavity with bone marrow and a thick outside covering of solid bone. A long bone is one whose length exceeds its width. There are two ends and a shaft to a long bone. An epiphyseal line and spongy bone can be found at the ends of long bones.
The femur and humerus are the long bones in the legs and arms, respectively. Despite having similar elements, their structures have been modified to serve various purposes.
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Long Bones Meaning
Bones can be classified as flat, long, short, and irregular bones based on their shape. Long bones mostly grow in length like the femur, humerus, fibula, tibia, radius and ulna.
The femur, fibula and tibia are identified as long bones in the lower limbs, while the humerus, ulna, and radius are considered long bones in the upper limbs. The exterior of long bones is protected by periosteum. The periosteum is a membrane of nerves and blood vessels that provides bones with their blood supplies and their feeling of sensation.
Long bones have two ends called epiphysis and a shaft, or the middle portion of the bone, called the diaphysis. The region between one shaft end and the adjoining epiphysis is called the metaphysis. Long bones are thinner in the middle, and their diameter increases as the subject proceeds from the shaft to the epiphysis.
Functions of Long Bones
The functions of long bones in the human body include the following:
- They provide movement and structure to the upper and lower extremities.
- They interact with tendons and muscles to allow limb movement.
- They act as levers to provide them with the most effective use of their muscles, including lifting objects and fast movement.
- Like all other bones, they are the storage and reservoirs of minerals like calcium, sodium, phosphorus, and magnesium, essential for regulating various physiological activities.
- The bone marrow of long bones can manufacture blood cells, i.e., red blood cells, white blood cells, and platelets.
Long bones are connected to two congenital diseases. Rachitis fetalis anularis is a condition where the epiphyses or ends of the long bones enlarge. Another condition, Rachitis fetalis micromelica, occurs when the growth of the long bones is insufficient.
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