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Lecture 24

BSC 215 Lecture Notes - Lecture 24: The Prime Mover, Skeletal Muscle, Cardiac Muscle


Department
Biological Sciences
Course Code
BSC 215
Professor
Jason Pienaar
Lecture
24

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Skeletal Muscle Actions
Knowing the muscular organization of each region of the body is crucial in anatomy.
With an understanding of where a muscle originates and inserts, you can calculate the
movements that will occur at a joint when these two points are brought together
following an isotonic muscular contraction. The orientation, placement, and coordination
of these muscles allow the human body to produce a wide range of voluntary
movements.
The muscular system consists of skeletal muscles and their associated
connective tissues. It does not include cardiac muscle and smooth muscle,
which are associated with the systems in which they are found, such as the
cardiovascular, digestive, urinary, or other organ systems.
A skeletal muscle is attached to one bone and extends across a joint to attach
to another bone. A muscle can also attach a bone to another structure, such
as skin. When the muscle contracts, one of the structures usually remains
stationary, while the other moves. The following terms refer to this
characteristic of muscle contraction:
The origin of the muscle is the muscle end that attaches to the stationary
structure, usually a bone or a bony structure.
The insertion of the muscle is the muscle end that attaches to the moving
structure.
The belly of the muscle is that part of the muscle between the origin and
insertion.
Several muscles usually influence a particular body movement:
The prime mover is the muscle that is most responsible for the movement.
Synergists are other muscles that assist the prime mover. Synergists may
stabilize nearby bones or refine the movement of the prime mover.
Antagonists are muscles that cause a movement opposite to that of the prime
mover. For example, if the prime mover raises an arm, its antagonist pulls the
arm down. An antagonist is generally attached to the opposite side of the joint to
which the prime mover is attached.
Major Skeletal Muscles
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