Questions and Answers
What are the functions of prime movers, antagonists, synergists, and fixators?
Prime mover: a muscle that has the major responsibility for producing a specific movement. Antagonist: muscles that oppose, or reverse, a particular movement. Synergist: helps prime movers by adding a little extra force to the same movement or by reducing undesirable or unnecessary movements. Fixator: when a synergist immobilizes a bone or a muscle's origin so that the prime mover has a stable base on which to act.
How does a muscle's position relative to a joint affect its action?
A muscle that crosses on the anterior side of a joint produces flexion. A muscle that crosses on the posterior side of a joint produces extension. A muscle that crosses on the lateral side of a joint produces abduction. A muscle that crosses on the medial side of a joint produces adduction.
What are the criteria used in naming muscles? Provide an example.
Muscle location: ex. temporalis overlies the temporal bone. Muscle shape: ex. deltoid is roughly triangular. Muscle size: ex. gluteus maximus vs. gluteus minimus. Direction of muscle fibers: ex. transversus abdominis runs transverse in the abdomen. Number of origins: ex. biceps brachii has two origins. Location of the attachments: ex. sternocleidomastoid has a dual origin on the sternum and clavicle and inserts on the mastoid process. Muscle action: ex. adductor longus.
Define a lever.
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What are the three types of lever systems?
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Study Notes
Muscle Functions
- Prime movers are responsible for initiating a specific movement in the body.
- Antagonists are muscles that act against prime movers, providing balance and control by reversing movements.
- Synergists assist prime movers by enhancing the force of the same movement or minimizing unwanted motions.
- Fixators stabilize the origin of prime movers, ensuring the muscle has a steady base for effective action.
Muscle Joint Mechanics
- Muscles crossing the anterior side of a joint typically cause flexion.
- Muscles that cross the posterior side promote extension.
- Muscles on the lateral side of a joint lead to abduction.
- Muscles situated on the medial side encourage adduction.
Criteria for Muscle Naming
- Muscle location: Example - Temporalis lies over the temporal bone.
- Muscle shape: Example - Deltoid has a triangular form.
- Muscle size: Example - Gluteus maximus is larger compared to gluteus minimus.
- Direction of muscle fibers: Example - Transversus abdominis fibers run horizontally.
- Number of origins: Example - Biceps brachii features two points of origin.
- Location of attachments: Example - Sternocleidomastoid connects from sternum/clavicle to the mastoid process.
- Muscle action: Example - Adductor longus functions to adduct the thigh.
Definition of a Lever
- A lever is a rigid structure that rotates around a fixed point called a fulcrum when force is applied.
Types of Lever Systems
- First-class lever (e.g., scissors): Fulcrum is between effort and load; offers mechanical advantage (strength) or disadvantage (speed).
- Second-class lever (e.g., wheelbarrow): Load is between fulcrum and effort; primarily provides strength.
- Third-class lever (e.g., tweezers): Effort is applied between load and fulcrum; focuses on speed of movement.
Major Muscles Identified
- Specific muscles of the human body, along with details on their origin, insertion, and function, are essential for understanding human anatomy but not provided in detail in this summary.
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Description
This quiz focuses on the functions of prime movers, antagonists, synergists, and fixators as outlined in Chapter 10. Understand the roles each muscle type plays in movement and how they interact with one another. Perfect for students looking to reinforce their knowledge in human anatomy and physiology.
