Why is the central tendon of diaphragm called a tendon when it does not connect the diaphragm to any bone?
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1$\begingroup$ Is there a requirement that tendons attach to bones? Histologically, it's just dense connective tissue. $\endgroup$– kmmCommented Apr 5, 2017 at 3:31
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$\begingroup$ @kmm Ligaments are similar to tendons and fasciae as they are all made of connective tissue. The differences in them are in the connections that they make: ligaments connect one bone to another bone, tendons connect muscle to bone, and fasciae connect muscles to other muscles. Wont this result in no difference in three, if tendon wont connect muscle to bone or something(like lens of eye)? $\endgroup$– Anubhav GoelCommented Apr 5, 2017 at 15:30
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1$\begingroup$ Not all ligaments connect one bone to another bone. ex; ligaments of liver which connect liver to abdomen, and other organs. $\endgroup$– JM97Commented Apr 5, 2017 at 16:04
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1$\begingroup$ The basic difference between ligament and tendon is that one restricts movements while other aides in movement. $\endgroup$– JM97Commented Apr 5, 2017 at 16:06
1 Answer
A tendon usually connects a muscle to a bone, but not always.
According to InnerBody, the diaphragm muscle originates at the lumbar vertebra, lower ribs and sternum and inserts to the central tendon.
The central tendon — a flat aponeurosis made of dense collagen fibers — acts as the tough insertion point of the muscles.
So, the central tendon acts as the diaphragm's own insertion.
A similar example is aponeurosis of the external oblique muscle in the lower part of the abdominal wall (Brazosport.edu, Picture 10.11.a.).
A tendon is the connective tissue that is always a part of a muscle and it fixes the muscle during its contraction.
A ligament is the connective tissue that merely connects two bones or two internal organs and is not actively involved in their movements.