Editing Long bone (section)

{{short description|Bone that is longer than it is wide}}
{{Infobox bone
| Name        = Long bone
| Latin       = os longum
| Image       = 603 Anatomy of Long Bone.jpg
| Caption     = Structure of a long bone (femur)
| Image2      = Long bones - anterior view - with legend.png
| Caption2    = Long bones in [[human skeleton]] (shown in red)
}}
The '''long bones''' are those that are longer than they are wide. They are one of five types of [[bone]]s: long, [[Short bone|short]], [[Flat bone|flat]], [[Irregular bone|irregular]] and [[Sesamoid bone|sesamoid]]. Long bones, especially the [[femur]] and [[tibia]], are subjected to most of the load during daily activities and they are crucial for skeletal mobility. They grow primarily by elongation of the [[diaphysis]], with an [[epiphysis]] at each end of the growing bone. The ends of epiphyses are covered with [[hyaline cartilage]] ("articular cartilage").  The longitudinal growth of long bones is a result of [[endochondral ossification]] at the [[epiphyseal plate]]. Bone growth in length is stimulated by the production of [[growth hormone]] (GH), a secretion of the [[Anterior pituitary|anterior lobe of the pituitary gland]].

The long bone category includes the femora, tibiae, and [[fibula]]e of the legs; the [[humerus|humeri]], [[Radius (bone)|radii]], and [[ulna]]e of the arms; [[metacarpals]] and [[metatarsals]] of the hands and feet, the [[Phalanx bones|phalanges]] of the fingers and toes, and the [[clavicle]]s or collar bones. The long bones of the human leg comprise nearly half of adult height. The other primary skeletal component of height are the [[vertebrae]] and [[human skull|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]].