Muscle: Difference between revisions
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Muscles are usually partly described by their origin at one end, and insertion at the other. These are points of the muscle that attach to bones - the origin being the point that moves least under contraction, and the insertion being the end that moves most. The origin is usually more proximal, and the insertion more distal. If a muscle arises from more than one place (as in the biceps, or triceps), we say that it has two (or more) heads. | Muscles are usually partly described by their origin at one end, and insertion at the other. These are points of the muscle that attach to bones - the origin being the point that moves least under contraction, and the insertion being the end that moves most. The origin is usually more proximal, and the insertion more distal. If a muscle arises from more than one place (as in the biceps, or triceps), we say that it has two (or more) heads. | ||
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Revision as of 00:28, 24 August 2006
Muscles are comprised of fascicles, which are bundles of muscle fibers. Surrounding each fascicle, and holding it together, is a layer of connective tissue known as the perimysium. Endomysium surrounds each muscle fiber, and epimysium surrounds the muscle itself.
Penetrating the muscle, are arteries, veins, and nerve fibers.
There are three types of muscle:
- Skeletal: Under voluntary nervous control.
- Cardiac: Found only in the heart, specialised and under nervous control.
- Smooth or visceral: Smooth or visceral: Not under voluntary nervous control. Found in blood vessels, digestive system, etc.
Origin and Insertion
Muscles are usually partly described by their origin at one end, and insertion at the other. These are points of the muscle that attach to bones - the origin being the point that moves least under contraction, and the insertion being the end that moves most. The origin is usually more proximal, and the insertion more distal. If a muscle arises from more than one place (as in the biceps, or triceps), we say that it has two (or more) heads.