Muscular System: Gross Anatomy
I. General Principles
A. General Terminology
1. Tendons attach muscles to bones
2. What is an aponeurosis?
A flat sheet or ribbon of tendon like material that anchors a muscle or connects it with the part that the muscle moves.
3. The points of muscle attachment are called origin & insertion.
4. How is the "origin" defined?
The point of muscle attachment which remains fixed during contraction.
5. How is the "insertion" defined?
The point of muscle attachment which moves toward the origin bone.
6. What is the "belly" of a muscle?
The part of the muscle between the origin and the insertion.
7. What is an agonist?
Also called prime mover, it provides the major force for movement.
8. What does an antagonist muscle do?
Opposes the movement produced by the prime mover.
9. Muscles that work together to create a movement are called synergist.
10. What is a "prime mover"?
Among a group of synergists, this muscle plays the major role in accomplishing the movement.
11. What does a "fixator" do?
Muscles that immobilize the bone or muscle origin, stabilizing that part of the body while other muscles are contracting.
B. Muscle Shapes
1. The shape and size of any given muscle greatly influences:
a. Degree to which it can contract &
b. Amount of force it can generate.
2. Describe the pennate arrangement of muscle fasciculi:
Fascicles originate from a tendon that runs the length of the entire muscle.
a. What does unipennate mean?
A type of pennate muscle wherein the muscle fibers or fascicles are all in one side of the tendon.
b. How are fasciculi arranged in a bipennate muscle?
the muscle fibers or fascicles are in opposite sides of the central tendon.
c. What is a multipennate muscle shape?
3. Describe the parallel arrangement of muscle fasciculi:
In a parallel arrangement, the length of the fascicles runs parallel to the long axis of the muscle.
a. This arrangement allows them to shorten more than pennate.
b. How does the force of contraction in parallel muscles compare to that in pennate muscles?
The force of contraction in parallel muscles are not very strong but have good endurance.
1. What accounts for this difference?
The pennate muscles have greater number of fibers than the parallel muscles.
4. Describe the convergent arrangement of muscle fasciculi:
A convergent muscle has a broad origin, and its fascicles converge toward a single tendon of insertion.
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Community College of Southern Nevada
a. This results in a fan-shaped muscles with different shape to the muscle.
b. How does the force of contraction compare to a parallel muscle?
These muscles do not tend to exert as much force on their tendons compared to parallel muscle.
5. Describe the circular arrangement of muscle fasciculi:
The fascicular pattern is circular when the fascicles are arranged in concentric rings.
a. These muscles act as a contracting agent to close the external body openings.
6. List the specific shapes that a muscle may have: (Use Figure 10.2 as needed)