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Questions and Answers
What is the primary function of skeletal muscles in the human body?
What is the term for muscles working together to perform joint actions?
What determines the force produced by a muscle?
What type of muscle fiber arrangement allows for greater range of motion?
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What is the term for the ability of muscles to respond to stimuli?
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What is the term for muscles that are located within a specific body region?
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What is the term for the nerve supply to muscles?
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What is the term for a flattened tendon that binds and connects muscles?
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What is the primary function of a retinaculum?
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What type of muscle contraction occurs when the muscle length does not change?
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What is the role of the cerebellum in movement?
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What type of proprioceptors detect changes in muscle tension?
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What is the principle that states that a motor unit will contract fully or not at all?
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What is the term for the reciprocal relaxation of an antagonist muscle during agonist contraction?
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What is the relationship between muscle length and force production?
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What is the term for the storage of energy during muscle stretch, which is then used during contraction?
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Study Notes
Skeletal Muscles
- Functions: Movement, protection, stability, posture, support, and heat production
- Aggregate muscle action: Muscles often work in groups to perform joint actions
Muscle Nomenclature
- Naming criteria: Visual appearance, anatomical position, and function
- Visual appearance: Shape (e.g., deltoid, rhomboid), size (e.g., gluteus maximus, teres minor)
- Anatomical position: Location (e.g., rectus femoris, palmaris longus), point of attachment (e.g., coracobrachialis, extensor hallucis longus)
- Function: Action (e.g., erector spinae, supinator), combinations (e.g., pronator quadratus, adductor magnus)
Shapes of Muscles and Fiber Arrangement
- Impact on force and range: Cross-sectional diameter and muscle length affect force production and range of motion
- Fiber arrangement types: Parallel (greater range of motion), pennate (higher force production)
- Examples: Brachialis (parallel), sartorius (parallel), orbicularis oris (parallel), biceps femoris (unipennate), rectus femoris (bipennate), deltoid (multipennate)
Muscle Properties
- Tissue properties: Irritability, contractility, extensibility, and elasticity
- Irritability: Responds to stimuli
- Contractility: Produces tension
- Extensibility: Stretches beyond resting length
- Elasticity: Returns to original length after stretching
Muscle Terminology
- Intrinsic vs. extrinsic muscles: Intrinsic muscles are located within a body region, while extrinsic muscles span across different body regions
- Muscle actions: Action, joint actions, and aggregate muscle action
- Action: Result of muscle contraction
- Joint actions: Movements such as flexion, extension, etc.
- Aggregate muscle action: Multiple muscles working together
Muscle Innervation and Amplitude
- Innervation: Nerve supply to muscles
- Amplitude: Range of muscle length from fully stretched to contracted
Muscle Structure and Tendons
- Gaster: Muscle belly containing contractile fibers
- Tendons: Connect muscles to bones
- Aponeurosis: Flattened tendon, binds and connects muscles
- Fascia: Connective tissue organizing muscles
- Retinaculum: Holds tendons in place
Origin and Insertion
- Origin: Proximal attachment, less moveable
- Insertion: Distal attachment, more moveable
Contraction Mechanics
- Muscles contract towards the center
- Stabilization affects which bone moves during contraction
Muscle Contraction Types
- Isometric: Muscle length doesn't change
- Isotonic: Muscle changes length
- Concentric: Muscle shortens
- Eccentric: Muscle lengthens
Roles in Movement
- Agonist: Primary mover
- Antagonist: Opposes agonist
- Synergists: Assist agonist
- Helping synergists: Assist and control movement
- True synergists: Prevent unwanted actions
- Stabilizers: Maintain stability
- Neutralizers: Counteract unwanted movements
- Force couples: Create rotational movements
Neural Control of Movement
- Levels: Cerebral cortex, basal ganglia, cerebellum, brainstem, and spinal cord
- Cerebral cortex: Decision-making
- Basal ganglia: Movement sequencing
- Cerebellum: Timing and refinement
- Brainstem: Balance and wakefulness
- Spinal cord: Reflexes and pathways
Proprioception and Kinesthesis
- Proprioceptors: Provide body position information
- Kinesthesis: Awareness of body movements
- Proprioceptors types: Muscle spindles, Golgi tendon organs, and cutaneous proprioceptors
Principles Affecting Force Production
- Neural control and motor units: Motor unit, all-or-none principle, and force production
- Motor unit: Single neuron and its fibers
- All-or-none principle: Full contraction or none
- Force production: Recruitment and frequency, length-tension relationship, and velocity-force relationship
- Elastic energy and stretch-shorten cycle: Elastic energy, reciprocal inhibition, and active and passive insufficiency
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