Skeletal system: Difference between revisions

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Skeletal system (view source)

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=== Bone ===
=== Bone ===
: ''Main Article: [[Bone]]''
[[Image:Compact and Spongy.jpg|thumb|350px|right|Diagram of the spongy and compact layers of the bone]]
[[Image:Compact and Spongy.jpg|thumb|350px|right|Diagram of the spongy and compact layers of the bone]]


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'''Glide'''
'''Glide'''
The glide joint is similar to the ball and socket joint in terms of the range of movement, but there is no actual ball and socket. An excellent example of this is a person's wrist, which has extreme mobility but no bulky ball and socket like the shoulder. Glide joints are also very delicate, and can be easily damaged. They are also very weak, and cannot apply very much  force by themselves. For example, try lifting a 30 lb weight with your whole arm, and then try lifting the same weight using just your wrist. Gliding joints are useful, but lack a lot of support that allows other joints to apply more force.
The glide joint is similar to the ball and socket joint in terms of the range of movement, but there is no actual ball and socket. An excellent example of this is a person's wrist, which has extreme mobility but no bulky ball and socket like the shoulder. Glide joints are also very delicate, and can be easily damaged. They are also very weak, and cannot apply very much  force by themselves. For example, try lifting a 30 lb weight with your whole arm, and then try lifting the same weight using just your wrist. Gliding joints are useful, but lack a lot of support that allows other joints to apply more force.
=== Broken Bones ===
Your bones are tough stuff - but even tough stuff can break. Like a wooden pencil, bones will bend under strain. Most fractures occur in the upper extremities: the wrist, the forearm, and above the elbow. Also if the pressure is too much, or too sudden, bones can snap. You can break a bone by falling off a skateboard or crashing down from the monkey bars.
Bones can fracture in a number of different ways. A fracture may be a straight break across the bone (transverse fracture), slanting (oblique fracture) or winding (spiral fracture). The break may run along the shaft of the bone (longitudinal fracture), or the bone may be shattered into pieces (comminuted fracture). Young bone is softer and more able to bend than adult bone, so childrens bones often fracture on one side but bend on the other - known as a greenstick fracture.[http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=166]
There are many different types of fracture, the most common of which is a simple fracture, when a bone breaks cleanly. If you put out your arms when you fall, you could end up with an impacted fracture, where the ends of two bones are forced into one another. A sharp sudden twist of a bone in a game of football could result in a jagged spiral fracture. Road accidents often cause comminuted fractures, where a bone breaks into fragments, or compression fractures, where a bone is crushed.[http://www.bbc.co.uk/science/humanbody/body/articles/skeleton/broken_bones.shtml]


== Exoskeleton ==
== Exoskeleton ==
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