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Questions and Answers
What movement occurs when the diaphragm contracts?
What movement occurs when the diaphragm contracts?
What is the primary function of the muscles that move the pectoral girdle?
What is the primary function of the muscles that move the pectoral girdle?
What is the function of the serratus anterior muscle?
What is the function of the serratus anterior muscle?
Which muscle permits rotation, adduction, and stabilization of the scapula?
Which muscle permits rotation, adduction, and stabilization of the scapula?
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What movement does the deltoid muscle primarily permit?
What movement does the deltoid muscle primarily permit?
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What type of control do skeletal muscles operate under?
What type of control do skeletal muscles operate under?
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Which term describes the end of a muscle attached to a stable or stationary bone?
Which term describes the end of a muscle attached to a stable or stationary bone?
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In a third-class lever system, where is the effort located?
In a third-class lever system, where is the effort located?
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Which type of lever produces a mechanical advantage?
Which type of lever produces a mechanical advantage?
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What is the main benefit of using third-class levers in the body?
What is the main benefit of using third-class levers in the body?
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Which muscle action is associated with standing on your toes?
Which muscle action is associated with standing on your toes?
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What defines the load in a lever system?
What defines the load in a lever system?
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What is a characteristic of first-class levers in the human body?
What is a characteristic of first-class levers in the human body?
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What role does the biceps brachii play during elbow joint flexion?
What role does the biceps brachii play during elbow joint flexion?
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What is the primary function of fixator muscles?
What is the primary function of fixator muscles?
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What happens when both the biceps brachii and triceps brachii contract simultaneously?
What happens when both the biceps brachii and triceps brachii contract simultaneously?
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What muscle group serves as a synergist to stabilize joints during movement?
What muscle group serves as a synergist to stabilize joints during movement?
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Which of the following describes the action of the orbicularis oris muscle?
Which of the following describes the action of the orbicularis oris muscle?
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What is the primary function of abdominal muscles?
What is the primary function of abdominal muscles?
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Which muscle elevates the mandible during chewing?
Which muscle elevates the mandible during chewing?
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What is the arrangement of fascicles in the external oblique muscles?
What is the arrangement of fascicles in the external oblique muscles?
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Which statement accurately describes the role of the diaphragm?
Which statement accurately describes the role of the diaphragm?
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The rectus abdominis is primarily responsible for which movement?
The rectus abdominis is primarily responsible for which movement?
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What is the function of the occipitofrontalis muscle's frontal belly?
What is the function of the occipitofrontalis muscle's frontal belly?
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Which muscle primarily pulls the corners of the mouth laterally?
Which muscle primarily pulls the corners of the mouth laterally?
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Which term describes a muscle that contracts to oppose the action of the agonist?
Which term describes a muscle that contracts to oppose the action of the agonist?
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How does the arrangement of abdominal muscle fascicles contribute to their function?
How does the arrangement of abdominal muscle fascicles contribute to their function?
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Study Notes
Skeletal Muscle Functions
- Skeletal muscles are under voluntary control.
- They support body movement and generate heat.
Muscle Anatomy
- Origin: The end of the muscle attached to the stabilized or stationary bone.
- Insertion: The end of the muscle attached to the moving bone.
- The muscle belly is the thickened portion between tendons.
- Actions: Movements possible when the muscle contracts.
- Reverse muscle actions (RMAs): Occur when the origin and insertion are reversed, allowing for different movements.
Levers
- Bones act as levers, moved by muscle effort.
- First-class levers: Fulcrum is between effort and load (e.g., looking up at the ceiling).
- Second-class levers: Load is between effort and fulcrum (e.g., standing on your toes).
- Third-class levers: Effort is between the fulcrum and the load (e.g., bending your elbow).
Muscle Groups
- Muscles usually work in opposing pairs (e.g., flexion at the elbow joint).
- Agonist: Muscle that exerts effort to move a lever.
- Antagonist: Muscle that opposes the agonist; must relax for the agonist to move the bone.
- Synergists: Muscles that stabilize joints when contracted, allowing movement at a specific joint.
- Fixators: Muscles that stabilize one end of a bone to allow movement of the other end.
Muscle Organization
- Muscles are organized into compartments.
- Each compartment contains a group of muscles, nerves, and blood vessels with specific functions.
Muscle Naming
- Muscles are named based on their:
- Direction
- Size
- Shape
- Action
- Number of origins
- Location
- Origin and insertion
Muscles of the Face
- Permit facial expressions, speech, vocalization, and chewing.
- Orbicularis oculi: Closes the eyelid.
- Orbicularis oris: Closes lips, purses lips.
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Occipitofrontalis: Has two bellies connected by the epicranial aponeurosis.
- Frontal belly: Raises eyebrows, wrinkles forehead.
- Occipital belly: Raises hair (pulls scalp posteriorly).
- Platysma: Pulls corners of the mouth laterally and inferiorly, depresses the mandible.
- Masseter & Temporalis: Elevate the mandible (masseter closes the jaw).
Muscles of the Neck
- Sternocleidomastoid: Rotates the head, extends the head at the atlanto-occipital joint, and elevates the sternum.
Muscles of the Abdomen
- Protect abdominal viscera and move the vertebral column.
- External obliques: Most superficial.
- Internal obliques: Intermediate to external obliques and transversus abdominis.
- Transversus abdominis: Deepest muscle.
- Rectus abdominis: Runs longitudinally along the anterior abdominal cavity.
Diaphragm
- Bounds the thoracic cavity inferiorly.
- Contracts to move downwards, expanding the lungs.
Muscles of the Pectoral Girdle
- Move the clavicle and scapula or stabilize the scapula during humerus movement.
- Serratus anterior: Abducts the scapula, elevates ribs, assists in pushing and punching.
- Trapezius: Permits rotation, adduction, depression, and stabilization of the scapula.
Muscles of the Upper Limb
- Move the humerus.
- Pectoralis Major: Permits adduction, medial rotation, and flexion of the arm.
- Deltoid: Permits abduction, medial/lateral rotation, flexion/extension of the arm.
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Description
Explore the essential functions and anatomy of skeletal muscles in this quiz. Learn about muscle origins, insertions, actions, and how bones act as levers. Test your understanding of muscle groups and their roles in movement.
