Introduction to muscles
From Wikiversity
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 autonomous. The nervous system has the ability to effect changes globally. [1]
- Smooth or visceral: Smooth or visceral: Not under voluntary nervous control. Found in blood vessels, digestive system, etc.
[edit] 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 possibly more) heads.
