4. Muscular System Flashcards
What is the primary function of muscular tissue?
Provides the body with its ability to move, regulate organ volumes, maintain posture, communicate, and produce body heat through ATP consumption.
List the common properties of muscle tissue.
- Electrical excitability
- Contractility
- Elasticity
- Extensibility
What are the three types of muscle tissue?
- Skeletal muscle
- Cardiac muscle
- Smooth muscle
What is electrical excitability in muscle tissue?
The ability of a muscle to respond to stimuli, such as neurotransmitters, by eliciting an electrical signal called an action potential.
Define contractility in the context of muscle tissue.
The ability of a muscle to shorten in response to an action potential.
What does extensibility refer to in muscle tissue?
The ability of a muscle to stretch (without injury).
Explain elasticity in muscle tissue.
The ability of a muscle to recover its original shape after contraction or extension.
What is the main characteristic of skeletal muscle?
Long cylindrical fibers, striated, with many peripheral nuclei.
Describe cardiac muscle.
Short, branched, striated fibers with a single central nucleus that contracts to pump blood.
What is the appearance of smooth muscle fibers?
Short, spindle-shaped, with no evident striation and a single nucleus in each fiber.
What is the primary role of smooth muscle in the body?
Concerned with involuntary movements such as moving food through the digestive system and regulating blood flow.
How do skeletal muscles contribute to body movement?
By contracting and relaxing to produce movement at various joints.
What role do muscles play in stabilizing joints?
They control and regulate the degree of movement possible at each joint.
What is thermogenesis in relation to muscle function?
The production of heat as a byproduct of contracting muscles, contributing to normal body temperature maintenance.
Fill in the blank: The contraction of smooth and skeletal muscle enables certain substances to be kept within one place, known as _______.
Storage of substances within the body.
True or False: Cardiac and smooth muscles are voluntary.
False
What is the function of actin and myosin in muscle contraction?
Actin is pulled by myosin to initiate the shortening of muscle fibers.
What happens to muscle fibers when calcium ions (Ca++) are removed?
Muscle fibers relax as the actin-binding sites are reshielded.
Define the term ‘syncytium’ as it relates to cardiac muscle.
A functional unit where the entire heart contracts as one due to the physical and electrical connections between cardiac muscle fibers.
How does smooth muscle differ from skeletal and cardiac muscle in terms of striation?
Smooth muscle appears nonstriated due to the less organized arrangement of actin and myosin.
What are the three types of muscles in the human body?
Skeletal, cardiac, and smooth.
What are fascicular muscles classified based on?
Arrangement, structure, size, and location.
List the five major categories of muscles.
- Fusiform
- Parallel
- Pennate
- Orbicular
- Convergent
True or False: There are hundreds of muscles in the human body that work together to perform various functions of the muscular system.
True
Fill in the blank: The three types of muscles are _______.
[skeletal, cardiac, smooth]
Q: What is electrical excitability in muscle tissue?
A: It’s the ability of a muscle to respond to stimuli by generating an electrical signal called an action potential.
Q: Define contractility in muscle tissue.
A: Contractility is the ability of muscle to shorten forcefully in response to an action potential.
Q: What does extensibility refer to in muscles?
A: It is the muscle’s ability to stretch without being damaged.
Q: What is elasticity in muscle tissue?
A: The ability of muscle to return to its original shape after being stretched or contracted.
Q: What are the three types of muscle tissue?
A: Skeletal, cardiac, and smooth muscle.
Q: Which muscle type is under voluntary control?
A: Skeletal muscle
Q: Which two muscle types are involuntary?
A: Cardiac and smooth muscle.
Q: Which muscle type has striations and multiple nuclei per fiber?
A: Skeletal muscle.
Q: What characterizes cardiac muscle histologically?
A: Short, branched, striated fibers with one central nucleus.
Q: How is smooth muscle histologically different from skeletal and cardiac muscle?
A: Smooth muscle fibers are short, spindle-shaped, have a single nucleus, and lack striations.
Q: What initiates contraction in all muscle types?
A: Interaction between actin and myosin, triggered by calcium ions (Ca++).
Q: What is the role of Ca++ in smooth muscle contraction?
A: It activates enzymes that then activate the myosin heads.
Q: What is the function of skeletal muscles around joints?
A: To stabilize joints and regulate the range of movement.
Q: Which muscle type is responsible for pumping blood?
A: Cardiac muscle.
Q: What functions are carried out by smooth muscle?
A: Moves food, controls respiration, moves secretions, and regulates blood flow.
Q: How do muscles contribute to thermogenesis?
A: Contracting muscles produce heat, helping maintain body temperature.
Q: What muscle is responsible for breathing, even during sleep?
A: The diaphragm, a skeletal muscle.
Q: How do skeletal muscles assist in communication?
A: They allow for both verbal and nonverbal expressions.
Q: What are the three connective tissue layers of a skeletal muscle?
A: Epimysium, perimysium, and endomysium.
Q: What is the function of the epimysium?
A: It wraps the entire muscle, allowing powerful contraction while maintaining structural integrity and separation from other tissues.
Q: What does the perimysium surround in skeletal muscle?
A: It surrounds bundles of muscle fibers called fascicles.
Q: What is a fascicle in skeletal muscle?
A: A bundled group of muscle fibers surrounded by perimysium.
Q: What tissue layer surrounds individual muscle fibers?
A: The endomysium.
Q: What is the endomysium composed of and what is its function?
A: It’s composed of collagen and reticular fibers; it supports muscle fibers and contains nutrients and extracellular fluid.
Q: What is the role of fascia in muscle structure?
A: It is connective tissue that lies between skin and bones, often serving as an attachment point for muscle.
Q: What is an aponeurosis?
A: A broad, tendon-like sheet of connective tissue that attaches muscle to bones or other muscles.
Q: How do skeletal muscles contribute to homeostasis?
A: By producing heat through ATP breakdown during contraction, especially noticeable during exercise and shivering.
Q: Why is muscle fascicle arrangement important?
A: It determines the force a muscle can generate and its range of motion.
Q: What is a convergent muscle?
A: A muscle with a broad origin and fascicles that converge to a single attachment point (e.g., pectoralis major).
Q: How are skeletal muscles activated to contract?
A: Through signaling from the nervous system via a somatic motor neuron’s axon branch.
Front
Back
How are fascicles arranged in parallel muscles?
In the same direction as the long axis of the muscle.
What is the ‘belly’ of a parallel muscle?
The central, thickest portion of the muscle between its origin and insertion.
What term describes a spindle-shaped parallel muscle with a large belly?
Fusiform muscle.
What are ‘strap’ muscles?
Parallel muscles that are long, flat, and have a consistent diameter throughout.
What is an example of a flat parallel muscle?
Transversus abdominis.
What is an example of a straight parallel muscle?
Rectus abdominis.
What are quadrate parallel muscles?
Muscles composed of short fibers running parallel to each other; e.g., pronator quadratus.
What is a two-bellied muscle?
A parallel muscle divided into two sections by a tendinous intersection, such as the omohyoid.
What shape is the biceps brachii considered to be?
A fusiform parallel muscle.
Front
Back
What is a fusiform muscle?
A muscle with a central belly that converges into one or more tendons, forming a spindle shape.
How do fusiform muscles differ from parallel muscles?
Fusiform muscles are spindle-shaped and always converge into at least one tendon, unlike parallel muscles.
What is a fusiform 1-headed muscle?
A muscle with one tendon at each end, such as the extensor carpi radialis longus.
What is an example of a fusiform 1-headed muscle?
The extensor carpi radialis longus in the posterior compartment of the forearm.
What is a fusiform 2-headed muscle?
A muscle with two tendons that merge and insert as one, such as the biceps brachii.
What is an example of a fusiform 2-headed muscle?
The biceps brachii in the upper arm.
What does the prefix ‘bi-‘ mean in ‘biceps brachii’?
It means two, referring to the muscle’s two heads.
What does the root word ‘fusion’ refer to in muscle terminology?
It refers to coming together, as in the central convergence of a fusiform muscle.
Front
Back
What are circular muscles also called?
Sphincters.
What happens when sphincters relax?
The concentrically arranged bundles of muscle fibers increase the size of the opening.
What happens when sphincters contract?
The size of the opening shrinks, potentially to the point of closure.
What is the function of the orbicularis oris muscle?
It surrounds the mouth and contracts to make the oral opening smaller, like when puckering the lips.
What is the function of the orbicularis oculi muscle?
It surrounds the eye and functions to close the eyelids.
What does the root ‘orb’ in orbicularis refer to?
‘Orb’ means circular, referencing a round or circular structure.
What does ‘oris’ in orbicularis oris refer to?
It refers to the oral cavity or mouth.
What does ‘oculi’ in orbicularis oculi refer to?
It refers to the eye.
What is the definition of a sphincter muscle?
A ring of concentrically arranged muscle fibers used to keep an opening within the body closed.
Front
Back
What are pennate muscles?
Muscles with fibers arranged at an angle to the tendon, like the structure of a feather.
What is the functional design of pennate muscles?
They pull at an angle and produce more tension for their size but do not move tendons very far.
What are the three types of pennate muscles?
Unipennate, bipennate, and multipennate.
What is a unipennate muscle?
A muscle with fascicles on only one side of the tendon.
What is an example of a unipennate muscle?
The flexor pollicis longus.
What is a bipennate muscle?
A muscle with fascicles on both sides of the tendon.
What is an example of a bipennate muscle?
The rectus femoris of the anterior thigh.
What is a multipennate muscle?
A muscle where fibers wrap around the tendon and may form individual fascicles.
What is an example of a multipennate muscle?
The deltoid muscle.
How can multipennate muscles like the deltoid change direction of pull?
By stimulating specific portions of the muscle through the nervous system.
What happens when the anterior fascicle of the deltoid is stimulated?
The arm abducts and flexes at the shoulder joint.
What does ‘oblique’ mean in muscle orientation?
Diagonal relative to the midline.
What does ‘rectus’ mean in muscle orientation?
Straight relative to the midline.
What does ‘transverse’ mean in muscle orientation?
Perpendicular to the midline.
What does ‘brevis’ mean?
Short.
What does ‘latissimus’ mean?
Widest.
What does ‘longissimus’ mean?
Longest.
What does ‘longus’ mean?
Long.
What does ‘magnus’ mean?
Large.
What does ‘maximus’ mean?
Largest.
What does ‘minimus’ mean?
Smallest.
What does ‘vastus’ mean?
Huge.
What does ‘major’ mean?
Larger.
What does ‘minor’ mean?
Smaller.
What does ‘pectinate’ mean?
Comb-like.
What does ‘platys’ mean?
Flat.
What does ‘quadrate’ mean?
Square.
What does ‘deltoid’ mean?
Triangular.
What does ‘gracilis’ mean?
Slender.
What does ‘piriformis’ mean?
Pear-shaped.
What does ‘rhomboid’ mean?
Diamond.
What does ‘serratus’ mean?
Saw-toothed.
What does ‘abductor’ mean?
Moves away from midline.
What does ‘adductor’ mean?
Moves toward midline.
What does ‘depressor’ mean?
Lowers.
What does ‘extensor’ mean?
Increases joint angle.
What does ‘levator’ mean?
Elevates.
What does ‘pronator’ mean?
Turns posteriorly.
What does ‘rotator’ mean?
Rotates around a longitudinal axis.
What does ‘sphincter’ mean?
Constricts an opening.
What does ‘supinator’ mean?
Turns anteriorly.
What does ‘tensor’ mean?
Makes rigid.
How many heads does a biceps muscle have?
Two heads (origins).
How many heads does a triceps muscle have?
Three heads (origins).
How many heads does a quadriceps muscle have?
Four heads (origins).
Where is the frontalis muscle located?
On top of the frontal bone of the skull.
What does ‘lateralis’ mean?
To the outside away from the midline.
What does ‘medialis’ mean?
Toward the midline.
What is the ‘origin’ of a muscle?
The end of the muscle attached to a fixed bone.
What is the ‘insertion’ of a muscle?
The movable end of the muscle that attaches to the bone being pulled.
What does ‘flexor’ indicate in a muscle name?
The muscle function is flexion.
What does ‘pollicis’ refer to?
The muscle of the hand.
What does ‘longus’ tell about a muscle?
That the muscle is long.
Where is the adductor pollicis found?
In the hand.
What Latin word means ‘diagonal’ and names muscles that run at an angle?
Oblique.
Which abdominal muscle is covered by the rectus sheath?
Rectus abdominis.
Which muscles form the three layers of the lateral abdominal wall?
External oblique, internal oblique, and transversus abdominis.
What is the function of the muscles of the lower back?
They move the lumbar spine and assist in femur movements.
Where are the deep transverse perineal muscles located?
In the perineum.
What is the Latin meaning of ‘pectoralis’?
Relating to the chest.
Where is the abductor pollicis brevis located?
In the hand; it helps move the thumb.
What does the latissimus dorsi muscle do?
It moves the humerus and is located in the middle or lower back.
What does the deltoid muscle do?
Moves the humerus; located on the shoulder.
Where is the adductor longus found?
In the inner thigh; it helps adduct the leg.
What does ‘medius’ mean in Latin?
Medium.
What does ‘externus’ mean?
Outside.
What does ‘internus’ mean?
Inside.
What does ‘multi’ mean?
Many.
What does ‘uni’ mean?
One.
What does ‘bi’ or ‘di’ mean?
Two.
What does ‘tri’ mean?
Three.
What does ‘quad’ mean?
Four.
What does ‘constrict’ mean?
To become or make something tighter, narrower, or less.
What is a ‘longitudinal axis’ in relation to muscle action?
An axis along the lengthwise direction of the body.
What determines a skeletal muscle’s anatomical name?
Its anatomical location or relationship to a particular bone.
What do the prefixes ‘bi-‘ and ‘tri-‘ indicate in muscle names?
The number of origins a muscle has.
What does ‘sternocleidomastoid’ tell us about the muscle?
It originates from the sternum and clavicle and inserts on the mastoid process.
What are examples of muscles that do not pull against the skeleton?
Facial muscles that control expressions, speech, and eyebrow movement.
What is the origin and insertion for muscles that control facial expression?
Both are in the skin, not bones.
How can muscle names help identify their function and location?
They often include terms for action, body part, and size or shape.
How can understanding Latin roots help with muscle names?
Latin roots describe the muscle’s size, shape, function, or location.
What does ‘oblique’ mean in muscle orientation?
Diagonal relative to the midline.
What does ‘rectus’ mean in muscle orientation?
Straight relative to the midline.
What does ‘transverse’ mean in muscle orientation?
Perpendicular to the midline.
What does ‘brevis’ mean?
Short.
What does ‘latissimus’ mean?
Widest.
What does ‘longissimus’ mean?
Longest.
What does ‘longus’ mean?
Long.
What does ‘magnus’ mean?
Large.
What does ‘maximus’ mean?
Largest.
What does ‘minimus’ mean?
Smallest.
What does ‘vastus’ mean?
Huge.
What does ‘major’ mean?
Larger.
What does ‘minor’ mean?
Smaller.
What does ‘pectinate’ mean?
Comb-like.
What does ‘platys’ mean?
Flat.
What does ‘quadrate’ mean?
Square.
What does ‘deltoid’ mean?
Triangular.
What does ‘gracilis’ mean?
Slender.
What does ‘piriformis’ mean?
Pear-shaped.
What does ‘rhomboid’ mean?
Diamond.
What does ‘serratus’ mean?
Saw-toothed.
What does ‘abductor’ mean?
Moves away from midline.
What does ‘adductor’ mean?
Moves toward midline.
What does ‘depressor’ mean?
Lowers.
What does ‘extensor’ mean?
Increases joint angle.
What does ‘levator’ mean?
Elevates.
What does ‘pronator’ mean?
Turns posteriorly.
What does ‘rotator’ mean?
Rotates around a longitudinal axis.
What does ‘sphincter’ mean?
Constricts an opening.
What does ‘supinator’ mean?
Turns anteriorly.
What does ‘tensor’ mean?
Makes rigid.
How many heads does a biceps muscle have?
Two heads (origins).
How many heads does a triceps muscle have?
Three heads (origins).
How many heads does a quadriceps muscle have?
Four heads (origins).
Where is the frontalis muscle located?
On top of the frontal bone of the skull.
What does ‘lateralis’ mean?
To the outside away from the midline.
What does ‘medialis’ mean?
Toward the midline.
What is the ‘origin’ of a muscle?
The end of the muscle attached to a fixed bone.
What is the ‘insertion’ of a muscle?
The movable end of the muscle that attaches to the bone being pulled.
What does ‘flexor’ indicate in a muscle name?
The muscle function is flexion.
What does ‘pollicis’ refer to?
The muscle of the hand.
What does ‘longus’ tell about a muscle?
That the muscle is long.
Where is the adductor pollicis found?
In the hand.
What Latin word means ‘diagonal’ and names muscles that run at an angle?
Oblique.
Which abdominal muscle is covered by the rectus sheath?
Rectus abdominis.
Which muscles form the three layers of the lateral abdominal wall?
External oblique, internal oblique, and transversus abdominis.
What is the function of the muscles of the lower back?
They move the lumbar spine and assist in femur movements.
Where are the deep transverse perineal muscles located?
In the perineum.
What is the Latin meaning of ‘pectoralis’?
Relating to the chest.
Where is the abductor pollicis brevis located?
In the hand; it helps move the thumb.
What does the latissimus dorsi muscle do?
It moves the humerus and is located in the middle or lower back.
What does the deltoid muscle do?
Moves the humerus; located on the shoulder.
Where is the adductor longus found?
In the inner thigh; it helps adduct the leg.
What does ‘medius’ mean in Latin?
Medium.
What does ‘externus’ mean?
Outside.
What does ‘internus’ mean?
Inside.
What does ‘multi’ mean?
Many.
What does ‘uni’ mean?
One.
What does ‘bi’ or ‘di’ mean?
Two.
What does ‘tri’ mean?
Three.
What does ‘quad’ mean?
Four.
What does ‘constrict’ mean?
To become or make something tighter, narrower, or less.
What is a ‘longitudinal axis’ in relation to muscle action?
An axis along the lengthwise direction of the body.
What determines a skeletal muscle’s anatomical name?
Its anatomical location or relationship to a particular bone.
What do the prefixes ‘bi-‘ and ‘tri-‘ indicate in muscle names?
The number of origins a muscle has.
What does ‘sternocleidomastoid’ tell us about the muscle?
It originates from the sternum and clavicle and inserts on the mastoid process.
What are examples of muscles that do not pull against the skeleton?
Facial muscles that control expressions, speech, and eyebrow movement.
What is the origin and insertion for muscles that control facial expression?
Both are in the skin, not bones.
How can muscle names help identify their function and location?
They often include terms for action, body part, and size or shape.
How can understanding Latin roots help with muscle names?
Latin roots describe the muscle’s size, shape, function, or location.
What is a lever in the musculoskeletal system?
A rigid object (bone) that moves around a fixed point (fulcrum).
What is a fulcrum in a lever system?
A fixed point or pivot around which the lever turns.
What is the ‘effort’ in a lever system?
The force applied to move a load.
What is the ‘load’ in a lever system?
The resistance or weight that must be moved.
What characterizes a first-class lever?
Fulcrum is between the load and effort (e.g., nodding the head).
What characterizes a second-class lever?
Load is between the fulcrum and effort (e.g., raising heels).
What characterizes a third-class lever?
Effort is between the fulcrum and load (e.g., bicep curl).
What is the agonist (prime mover)?
The main muscle responsible for a particular movement.
What is an antagonist muscle?
A muscle that opposes the action of the agonist.
What is a synergist muscle?
A muscle that assists the agonist in performing its action.
What is a fixator?
A synergist that stabilizes the bone for the prime mover’s origin.
What is an example of an agonist-antagonist pair in the arm?
Biceps brachii (agonist) and triceps brachii (antagonist).
What is an example of an agonist-antagonist pair in the thigh?
Quadriceps femoris (agonist for extension) and hamstrings (antagonist).
What role do antagonists play in movement?
They maintain position and control rapid movement.
Do all skeletal muscles move bones?
No, some control facial expressions, speech, or regulate openings like sphincters.
What is a muscle compartment?
A group of muscles separated by fascia, often sharing nerve and blood supply.
What is fascia?
A thin sheet of connective tissue that binds muscles into compartments.
What are septa?
Walls of connective tissue dividing muscle compartments.
What muscles are in the medial compartment of the thigh?
Adductor longus, adductor brevis, adductor magnus, pectineus, and gracilis.
What action do muscles in the medial thigh compartment perform?
Adduct the femur at the hip.
What are two benefits of muscle compartmentalization?
Prevents spread of infection and aids venous return.
How do muscles create movement?
By acting on specific points on bones.
What determines the class of a lever?
The relative positions of the fulcrum, load, and effort.
Which lever type provides the most range of motion?
Third-class levers.
Which lever type provides the greatest force?
Second-class levers.
Which lever type resembles a seesaw?
First-class levers.
What does ‘oblique’ mean in muscle orientation?
Diagonal relative to the midline.
What does ‘rectus’ mean in muscle orientation?
Straight relative to the midline.
What does ‘transverse’ mean in muscle orientation?
Perpendicular to the midline.
What does ‘brevis’ mean?
Short.
What does ‘latissimus’ mean?
Widest.
What does ‘longissimus’ mean?
Longest.
What does ‘longus’ mean?
Long.
What does ‘magnus’ mean?
Large.
What does ‘maximus’ mean?
Largest.
What does ‘minimus’ mean?
Smallest.
What does ‘vastus’ mean?
Huge.
What does ‘major’ mean?
Larger.
What does ‘minor’ mean?
Smaller.
What does ‘pectinate’ mean?
Comb-like.
What does ‘platys’ mean?
Flat.
What does ‘quadrate’ mean?
Square.
What does ‘deltoid’ mean?
Triangular.
What does ‘gracilis’ mean?
Slender.
What does ‘piriformis’ mean?
Pear-shaped.
What does ‘rhomboid’ mean?
Diamond.
What does ‘serratus’ mean?
Saw-toothed.
What does ‘abductor’ mean?
Moves away from midline.
What does ‘adductor’ mean?
Moves toward midline.
What does ‘depressor’ mean?
Lowers.
What does ‘extensor’ mean?
Increases joint angle.
What does ‘levator’ mean?
Elevates.
What does ‘pronator’ mean?
Turns posteriorly.
What does ‘rotator’ mean?
Rotates around a longitudinal axis.
What does ‘sphincter’ mean?
Constricts an opening.
What does ‘supinator’ mean?
Turns anteriorly.
What does ‘tensor’ mean?
Makes rigid.
How many heads does a biceps muscle have?
Two heads (origins).
How many heads does a triceps muscle have?
Three heads (origins).
How many heads does a quadriceps muscle have?
Four heads (origins).
Where is the frontalis muscle located?
On top of the frontal bone of the skull.
What does ‘lateralis’ mean?
To the outside away from the midline.
What does ‘medialis’ mean?
Toward the midline.
What is the ‘origin’ of a muscle?
The end of the muscle attached to a fixed bone.
What is the ‘insertion’ of a muscle?
The movable end of the muscle that attaches to the bone being pulled.
What does ‘flexor’ indicate in a muscle name?
The muscle function is flexion.
What does ‘pollicis’ refer to?
The muscle of the hand.
What does ‘longus’ tell about a muscle?
That the muscle is long.
Where is the adductor pollicis found?
In the hand.
What Latin word means ‘diagonal’ and names muscles that run at an angle?
Oblique.
Which abdominal muscle is covered by the rectus sheath?
Rectus abdominis.
Which muscles form the three layers of the lateral abdominal wall?
External oblique, internal oblique, and transversus abdominis.
What is the function of the muscles of the lower back?
They move the lumbar spine and assist in femur movements.
Where are the deep transverse perineal muscles located?
In the perineum.
What is the Latin meaning of ‘pectoralis’?
Relating to the chest.
Where is the abductor pollicis brevis located?
In the hand; it helps move the thumb.
What does the latissimus dorsi muscle do?
It moves the humerus and is located in the middle or lower back.
What does the deltoid muscle do?
Moves the humerus; located on the shoulder.
Where is the adductor longus found?
In the inner thigh; it helps adduct the leg.
What does ‘medius’ mean in Latin?
Medium.
What does ‘externus’ mean?
Outside.
What does ‘internus’ mean?
Inside.
What does ‘multi’ mean?
Many.
What does ‘uni’ mean?
One.
What does ‘bi’ or ‘di’ mean?
Two.
What does ‘tri’ mean?
Three.
What does ‘quad’ mean?
Four.
What does ‘constrict’ mean?
To become or make something tighter, narrower, or less.
What is a ‘longitudinal axis’ in relation to muscle action?
An axis along the lengthwise direction of the body.
What determines a skeletal muscle’s anatomical name?
Its anatomical location or relationship to a particular bone.
What do the prefixes ‘bi-‘ and ‘tri-‘ indicate in muscle names?
The number of origins a muscle has.
What does ‘sternocleidomastoid’ tell us about the muscle?
It originates from the sternum and clavicle and inserts on the mastoid process.
What are examples of muscles that do not pull against the skeleton?
Facial muscles that control expressions, speech, and eyebrow movement.
What is the origin and insertion for muscles that control facial expression?
Both are in the skin, not bones.
How can muscle names help identify their function and location?
They often include terms for action, body part, and size or shape.
How can understanding Latin roots help with muscle names?
Latin roots describe the muscle’s size, shape, function, or location.
What is a lever in the musculoskeletal system?
A rigid object (bone) that moves around a fixed point (fulcrum).
What is a fulcrum in a lever system?
A fixed point or pivot around which the lever turns.
What is the ‘effort’ in a lever system?
The force applied to move a load.
What is the ‘load’ in a lever system?
The resistance or weight that must be moved.
What characterizes a first-class lever?
Fulcrum is between the load and effort (e.g., nodding the head).
What characterizes a second-class lever?
Load is between the fulcrum and effort (e.g., raising heels).
What characterizes a third-class lever?
Effort is between the fulcrum and load (e.g., bicep curl).
What is the agonist (prime mover)?
The main muscle responsible for a particular movement.
What is an antagonist muscle?
A muscle that opposes the action of the agonist.
What is a synergist muscle?
A muscle that assists the agonist in performing its action.
What is a fixator?
A synergist that stabilizes the bone for the prime mover’s origin.
What is an example of an agonist-antagonist pair in the arm?
Biceps brachii (agonist) and triceps brachii (antagonist).
What is an example of an agonist-antagonist pair in the thigh?
Quadriceps femoris (agonist for extension) and hamstrings (antagonist).
What role do antagonists play in movement?
They maintain position and control rapid movement.
Do all skeletal muscles move bones?
No, some control facial expressions, speech, or regulate openings like sphincters.
What is a muscle compartment?
A group of muscles separated by fascia, often sharing nerve and blood supply.
What is fascia?
A thin sheet of connective tissue that binds muscles into compartments.
What are septa?
Walls of connective tissue dividing muscle compartments.
What muscles are in the medial compartment of the thigh?
Adductor longus, adductor brevis, adductor magnus, pectineus, and gracilis.
What action do muscles in the medial thigh compartment perform?
Adduct the femur at the hip.
What are two benefits of muscle compartmentalization?
Prevents spread of infection and aids venous return.
How do muscles create movement?
By acting on specific points on bones.
What determines the class of a lever?
The relative positions of the fulcrum, load, and effort.
Which lever type provides the most range of motion?
Third-class levers.
Which lever type provides the greatest force?
Second-class levers.
Which lever type resembles a seesaw?
First-class levers.
What does ‘oblique’ mean in muscle orientation?
Diagonal relative to the midline.
What does ‘rectus’ mean in muscle orientation?
Straight relative to the midline.
What does ‘transverse’ mean in muscle orientation?
Perpendicular to the midline.
What does ‘brevis’ mean?
Short.
What does ‘latissimus’ mean?
Widest.
What does ‘longissimus’ mean?
Longest.
What does ‘longus’ mean?
Long.
What does ‘magnus’ mean?
Large.
What does ‘maximus’ mean?
Largest.
What does ‘minimus’ mean?
Smallest.
What does ‘vastus’ mean?
Huge.
What does ‘major’ mean?
Larger.
What does ‘minor’ mean?
Smaller.
What does ‘pectinate’ mean?
Comb-like.
What does ‘platys’ mean?
Flat.
What does ‘quadrate’ mean?
Square.
What does ‘deltoid’ mean?
Triangular.
What does ‘gracilis’ mean?
Slender.
What does ‘piriformis’ mean?
Pear-shaped.
What does ‘rhomboid’ mean?
Diamond.
What does ‘serratus’ mean?
Saw-toothed.
What does ‘abductor’ mean?
Moves away from midline.
What does ‘adductor’ mean?
Moves toward midline.
What does ‘depressor’ mean?
Lowers.
What does ‘extensor’ mean?
Increases joint angle.
What does ‘levator’ mean?
Elevates.
What does ‘pronator’ mean?
Turns posteriorly.
What does ‘rotator’ mean?
Rotates around a longitudinal axis.
What does ‘sphincter’ mean?
Constricts an opening.
What does ‘supinator’ mean?
Turns anteriorly.
What does ‘tensor’ mean?
Makes rigid.
How many heads does a biceps muscle have?
Two heads (origins).
How many heads does a triceps muscle have?
Three heads (origins).
How many heads does a quadriceps muscle have?
Four heads (origins).
Where is the frontalis muscle located?
On top of the frontal bone of the skull.
What does ‘lateralis’ mean?
To the outside away from the midline.
What does ‘medialis’ mean?
Toward the midline.
What is the ‘origin’ of a muscle?
The end of the muscle attached to a fixed bone.
What is the ‘insertion’ of a muscle?
The movable end of the muscle that attaches to the bone being pulled.
What does ‘flexor’ indicate in a muscle name?
The muscle function is flexion.
What does ‘pollicis’ refer to?
The muscle of the hand.
What does ‘longus’ tell about a muscle?
That the muscle is long.
Where is the adductor pollicis found?
In the hand.
What Latin word means ‘diagonal’ and names muscles that run at an angle?
Oblique.
Which abdominal muscle is covered by the rectus sheath?
Rectus abdominis.
Which muscles form the three layers of the lateral abdominal wall?
External oblique, internal oblique, and transversus abdominis.
What is the function of the muscles of the lower back?
They move the lumbar spine and assist in femur movements.
Where are the deep transverse perineal muscles located?
In the perineum.
What is the Latin meaning of ‘pectoralis’?
Relating to the chest.
Where is the abductor pollicis brevis located?
In the hand; it helps move the thumb.
What does the latissimus dorsi muscle do?
It moves the humerus and is located in the middle or lower back.
What does the deltoid muscle do?
Moves the humerus; located on the shoulder.
Where is the adductor longus found?
In the inner thigh; it helps adduct the leg.
What does ‘medius’ mean in Latin?
Medium.
What does ‘externus’ mean?
Outside.
What does ‘internus’ mean?
Inside.
What does ‘multi’ mean?
Many.
What does ‘uni’ mean?
One.
What does ‘bi’ or ‘di’ mean?
Two.
What does ‘tri’ mean?
Three.
What does ‘quad’ mean?
Four.
What does ‘constrict’ mean?
To become or make something tighter, narrower, or less.
What is a ‘longitudinal axis’ in relation to muscle action?
An axis along the lengthwise direction of the body.
What determines a skeletal muscle’s anatomical name?
Its anatomical location or relationship to a particular bone.
What do the prefixes ‘bi-‘ and ‘tri-‘ indicate in muscle names?
The number of origins a muscle has.
What does ‘sternocleidomastoid’ tell us about the muscle?
It originates from the sternum and clavicle and inserts on the mastoid process.
What are examples of muscles that do not pull against the skeleton?
Facial muscles that control expressions, speech, and eyebrow movement.
What is the origin and insertion for muscles that control facial expression?
Both are in the skin, not bones.
How can muscle names help identify their function and location?
They often include terms for action, body part, and size or shape.
How can understanding Latin roots help with muscle names?
Latin roots describe the muscle’s size, shape, function, or location.
What is a lever in the musculoskeletal system?
A rigid object (bone) that moves around a fixed point (fulcrum).
What is a fulcrum in a lever system?
A fixed point or pivot around which the lever turns.
What is the ‘effort’ in a lever system?
The force applied to move a load.
What is the ‘load’ in a lever system?
The resistance or weight that must be moved.
What characterizes a first-class lever?
Fulcrum is between the load and effort (e.g., nodding the head).
What characterizes a second-class lever?
Load is between the fulcrum and effort (e.g., raising heels).
What characterizes a third-class lever?
Effort is between the fulcrum and load (e.g., bicep curl).
What is the agonist (prime mover)?
The main muscle responsible for a particular movement.
What is an antagonist muscle?
A muscle that opposes the action of the agonist.
What is a synergist muscle?
A muscle that assists the agonist in performing its action.
What is a fixator?
A synergist that stabilizes the bone for the prime mover’s origin.
What is an example of an agonist-antagonist pair in the arm?
Biceps brachii (agonist) and triceps brachii (antagonist).
What is an example of an agonist-antagonist pair in the thigh?
Quadriceps femoris (agonist for extension) and hamstrings (antagonist).
What role do antagonists play in movement?
They maintain position and control rapid movement.
Do all skeletal muscles move bones?
No, some control facial expressions, speech, or regulate openings like sphincters.
What is a muscle compartment?
A group of muscles separated by fascia, often sharing nerve and blood supply.
What is fascia?
A thin sheet of connective tissue that binds muscles into compartments.
What are septa?
Walls of connective tissue dividing muscle compartments.
What muscles are in the medial compartment of the thigh?
Adductor longus, adductor brevis, adductor magnus, pectineus, and gracilis.
What action do muscles in the medial thigh compartment perform?
Adduct the femur at the hip.
What are two benefits of muscle compartmentalization?
Prevents spread of infection and aids venous return.
How do muscles create movement?
By acting on specific points on bones.
What determines the class of a lever?
The relative positions of the fulcrum, load, and effort.
Which lever type provides the most range of motion?
Third-class levers.
Which lever type provides the greatest force?
Second-class levers.
Which lever type resembles a seesaw?
First-class levers.
What everyday object is used as an analogy for the musculoskeletal lever system?
A hammer used to remove a nail.
How does the musculoskeletal system act like a lever?
Bones act as levers, joints as fulcrums, muscles provide effort, and body parts or weights act as loads.
Why are skeletal muscles arranged in pairs?
To provide balanced movements, with one muscle contracting and the other relaxing.
What does the term ‘flexion’ mean?
Movement that decreases the angle of a joint.
What do the facial muscles attach to instead of bone?
They attach to skin to create expressions.
What is the role of the diaphragm in movement?
It changes the volume of the pleural cavities for breathing, without moving the skeleton.
What is the function of skeletal muscles in the urinary and anal sphincters?
They allow voluntary control over urination and defecation.
What separates muscle compartments from each other?
Fascia and septa.
What are the three compartments of the thigh?
Medial, anterior, and posterior.
What action do the anterior thigh muscles perform?
Extend the lower leg and flex the thigh.
What action do the posterior thigh muscles perform?
Flex the lower leg and extend the thigh.
What is the role of compartmentalization in circulation?
Provides pressure around veins to aid venous return.
Where is cardiac muscle found?
In the walls of the heart.
What is the myocardium?
The muscular walls of the heart made of cardiac muscle.
What are cardiomyocytes?
Cardiac muscle cells adapted for continuous contraction.
What feature allows cardiac cells to contract without stimulation?
They are self-excitable.
How are cardiac muscle fibers shaped?
Short, branched, and joined by intercalated discs.
What is the role of mitochondria in cardiac muscle?
Provide constant ATP for energy.
What is the sarcolemma?
The plasma membrane of a cardiac muscle cell.
What are transverse tubules?
Invaginations of the sarcolemma that help spread excitation.
What is the sarcoplasmic reticulum?
Calcium reservoir for contraction.
What are myofibrils?
Cylindrical bundles responsible for contraction.
What are intercalated discs?
Junctions between cardiac cells containing desmosomes and gap junctions.
What is a desmosome?
Anchors cardiac cells to resist mechanical stress.
What is a gap junction?
Allows ions and molecules to pass for electrical coordination.
What is a syncytium in cardiac muscle?
A network of electrically connected fibers contracting as a unit.
Where is smooth muscle found?
In walls of internal organs, blood vessels, and eye muscles.
Is smooth muscle voluntary or involuntary?
Involuntary.
What is the shape of smooth muscle fibers?
Spindle-shaped with a single central nucleus.
Why is smooth muscle unstriated?
Because filaments are not arranged in sarcomeres.
What is peristalsis?
Wavelike muscle contractions that move contents through organs.
What is calmodulin?
Calcium-binding protein in smooth muscle replacing troponin.
What enzyme does calmodulin activate?
Myosin light chain kinase.
What does myosin light chain kinase do?
Phosphorylates myosin to initiate contraction.
What are caveolae?
Plasma membrane invaginations containing extracellular calcium.
What are dense bodies?
Anchors for thin filaments, aiding in contraction.
What is hyperplasia?
Ability of smooth muscle to divide and produce more cells.
Where is hyperplasia observed?
In the uterus at puberty due to estrogen stimulation.
What type of respiration do cardiac and smooth muscles use?
Aerobic.
What is the fatigue resistance level of cardiac and smooth muscles?
High.
Do cardiac and smooth muscle fibers have one nucleus?
Yes, they are mononucleated.
Are cardiac muscle fibers striated?
Yes.
Are smooth muscle fibers striated?
No.
What is the function of cardiac muscle?
Contract the atria and ventricles of the heart.
What is the function of single unit smooth muscle?
Propels and expels liquids in the body.
What is the function of multi-unit smooth muscle?
Regulates diameter of vessels.
What is skeletal muscle attached to?
The skeleton via tendons or aponeurosis.
Is skeletal muscle voluntary or involuntary?
Voluntary.
What is the muscle belly?
The bulky central body of a muscle.
What are the three connective tissue layers of skeletal muscle?
Epimysium, perimysium, and endomysium.
What is the epimysium?
A sheath that surrounds the entire skeletal muscle.
What is the perimysium?
A layer that groups muscle fibers into fascicles.
What is the endomysium?
A thin layer that surrounds each individual muscle fiber.
What is a muscle fascicle?
A bundle of skeletal muscle fibers.
What is the order of organization from smallest to largest in muscle?
Myofilaments → myofibrils → muscle fibers → fascicles → muscle.
How does skeletal muscle help with posture?
By making small constant adjustments to maintain balance.
What is the role of skeletal muscle in thermoregulation?
It generates heat through ATP breakdown during contraction.
What is a sarcomere?
The functional unit of a muscle fiber.
What gives skeletal muscle a striated appearance?
The arrangement of actin and myosin filaments.
What is the Z-line?
The dense protein disc marking the end of a sarcomere.
What is the I-band?
The lighter band made of only thin actin filaments.
What is the A-band?
A dark band with thick myosin and overlapping thin filaments.
What is the H-zone?
The central area of the A-band with only thick filaments.
What is the M-line?
The middle of the sarcomere where thick filaments are anchored.
What causes contraction in the sarcomere?
The sliding of actin and myosin filaments triggered by calcium release.
What are the two main contractile proteins?
Actin and myosin.
What is the role of actin?
Forms thin filaments and provides binding sites for myosin.
What is the role of myosin?
Forms thick filaments and moves along actin to cause contraction.
What are the three domains of myosin?
Head, neck, and tail.
What is tropomyosin?
A regulatory protein that blocks myosin-binding sites on actin.
What is troponin?
A regulatory protein that moves tropomyosin when bound to calcium.
How does calcium trigger contraction?
Calcium binds to troponin, which moves tropomyosin to expose myosin-binding sites.
What does ‘oblique’ mean in muscle orientation?
Diagonal relative to the midline.
What does ‘rectus’ mean in muscle orientation?
Straight relative to the midline.
What does ‘transverse’ mean in muscle orientation?
Perpendicular to the midline.
What does ‘brevis’ mean?
Short.
What does ‘latissimus’ mean?
Widest.
What does ‘longissimus’ mean?
Longest.
What does ‘longus’ mean?
Long.
What does ‘magnus’ mean?
Large.
What does ‘maximus’ mean?
Largest.
What does ‘minimus’ mean?
Smallest.
What does ‘vastus’ mean?
Huge.
What does ‘major’ mean?
Larger.
What does ‘minor’ mean?
Smaller.
What does ‘pectinate’ mean?
Comb-like.
What does ‘platys’ mean?
Flat.
What does ‘quadrate’ mean?
Square.
What does ‘deltoid’ mean?
Triangular.
What does ‘gracilis’ mean?
Slender.
What does ‘piriformis’ mean?
Pear-shaped.
What does ‘rhomboid’ mean?
Diamond.
What does ‘serratus’ mean?
Saw-toothed.
What does ‘abductor’ mean?
Moves away from midline.
What does ‘adductor’ mean?
Moves toward midline.
What does ‘depressor’ mean?
Lowers.
What does ‘extensor’ mean?
Increases joint angle.
What does ‘levator’ mean?
Elevates.
What does ‘pronator’ mean?
Turns posteriorly.
What does ‘rotator’ mean?
Rotates around a longitudinal axis.
What does ‘sphincter’ mean?
Constricts an opening.
What does ‘supinator’ mean?
Turns anteriorly.
What does ‘tensor’ mean?
Makes rigid.
How many heads does a biceps muscle have?
Two heads (origins).
How many heads does a triceps muscle have?
Three heads (origins).
How many heads does a quadriceps muscle have?
Four heads (origins).
What is the ‘origin’ of a muscle?
The end of the muscle attached to a fixed bone.
What is the ‘insertion’ of a muscle?
The movable end of the muscle that attaches to the bone being pulled.
What is a lever in the musculoskeletal system?
A rigid object (bone) that moves around a fixed point (fulcrum).
What is a fulcrum in a lever system?
A fixed point or pivot around which the lever turns.
What is the ‘effort’ in a lever system?
The force applied to move a load.
What is the ‘load’ in a lever system?
The resistance or weight that must be moved.
What characterizes a first-class lever?
Fulcrum is between the load and effort (e.g., nodding the head).
What characterizes a second-class lever?
Load is between the fulcrum and effort (e.g., raising heels).
What characterizes a third-class lever?
Effort is between the fulcrum and load (e.g., bicep curl).
What is an agonist (prime mover)?
The main muscle responsible for a particular movement.
What is an antagonist muscle?
A muscle that opposes the action of the agonist.
What is a synergist muscle?
A muscle that assists the agonist in performing its action.
What is a fixator?
A synergist that stabilizes the bone for the prime mover’s origin.
What is a muscle compartment?
A group of muscles separated by fascia, often sharing nerve and blood supply.
What is fascia?
A thin sheet of connective tissue that binds muscles into compartments.
What are septa?
Walls of connective tissue dividing muscle compartments.
Where is cardiac muscle found?
In the walls of the heart.
What are cardiomyocytes?
Cardiac muscle cells adapted for continuous contraction.
What is the sarcolemma?
The plasma membrane of a cardiac muscle cell.
What are transverse tubules?
Invaginations of the sarcolemma that help spread excitation.
What are intercalated discs?
Junctions between cardiac cells containing desmosomes and gap junctions.
What is a syncytium in cardiac muscle?
A network of electrically connected fibers contracting as a unit.
Where is smooth muscle found?
In walls of internal organs, blood vessels, and eye muscles.
What is calmodulin?
Calcium-binding protein in smooth muscle replacing troponin.
What enzyme does calmodulin activate?
Myosin light chain kinase.
What are caveolae?
Plasma membrane invaginations containing extracellular calcium.
What is hyperplasia?
Ability of smooth muscle to divide and produce more cells.
What is skeletal muscle attached to?
The skeleton via tendons or aponeurosis.
Is skeletal muscle voluntary or involuntary?
Voluntary.
What is the muscle belly?
The bulky central body of a muscle.
What are the three connective tissue layers of skeletal muscle?
Epimysium, perimysium, and endomysium.
What is the epimysium?
A sheath that surrounds the entire skeletal muscle.
What is the perimysium?
A layer that groups muscle fibers into fascicles.
What is the endomysium?
A thin layer that surrounds each individual muscle fiber.
What is a muscle fascicle?
A bundle of skeletal muscle fibers.
What is the order of organization from smallest to largest in muscle?
Myofilaments → myofibrils → muscle fibers → fascicles → muscle.
How does skeletal muscle help with posture?
By making small constant adjustments to maintain balance.
What is the role of skeletal muscle in thermoregulation?
It generates heat through ATP breakdown during contraction.
What is a sarcomere?
The functional unit of a muscle fiber.
What gives skeletal muscle a striated appearance?
The arrangement of actin and myosin filaments.
What is the Z-line?
The dense protein disc marking the end of a sarcomere.
What is the I-band?
The lighter band made of only thin actin filaments.
What is the A-band?
A dark band with thick myosin and overlapping thin filaments.
What is the H-zone?
The central area of the A-band with only thick filaments.
What is the M-line?
The middle of the sarcomere where thick filaments are anchored.
What causes contraction in the sarcomere?
The sliding of actin and myosin filaments triggered by calcium release.
What are the two main contractile proteins?
Actin and myosin.
What is the role of actin?
Forms thin filaments and provides binding sites for myosin.
What is the role of myosin?
Forms thick filaments and moves along actin to cause contraction.
What are the three domains of myosin?
Head, neck, and tail.
What is tropomyosin?
A regulatory protein that blocks myosin-binding sites on actin.
What is troponin?
A regulatory protein that moves tropomyosin when bound to calcium.
How does calcium trigger contraction?
Calcium binds to troponin, which moves tropomyosin to expose myosin-binding sites.
What triggers the release of calcium ions from the sarcoplasmic reticulum?
An action potential depolarizing the T-tubules.
What is the role of calcium ions in muscle contraction?
They bind to troponin, causing tropomyosin to move and expose actin-binding sites.
What does ATP do in the muscle contraction cycle?
ATP provides energy for the power stroke and detachment of myosin from actin.
What happens to muscles when ATP runs out?
They become fatigued and may enter rigor mortis due to inability to detach myosin from actin.
Name the three ways muscles regenerate ATP.
Creatine phosphate metabolism, anaerobic glycolysis, and aerobic respiration.
Which ATP regeneration method is fastest but least sustainable?
Creatine phosphate metabolism.
Which process produces the most ATP per glucose molecule?
Aerobic respiration.
What causes the power stroke in the cross-bridge cycle?
The release of ADP and phosphate from the myosin head.
What returns the myosin head to the cocked position?
Hydrolysis of ATP to ADP and phosphate.
What is rigor mortis and why does it occur?
Postmortem muscle stiffness due to lack of ATP preventing myosin-actin detachment.
What neurotransmitter is used at the neuromuscular junction?
Acetylcholine (ACh).
What is the role of synaptic vesicles?
They store and release ACh into the synaptic cleft upon nerve stimulation.
What is the synaptic cleft?
The small gap between the neuron and muscle fiber at the NMJ.
Where are acetylcholine receptors located?
On the motor end plate of the muscle fiber.
What breaks down acetylcholine in the synaptic cleft?
Acetylcholinesterase (AChE).
What happens when ACh binds to its receptor?
Ligand-gated sodium channels open, causing depolarization of the muscle fiber membrane.
What is excitation-contraction coupling?
The process linking muscle fiber excitation to contraction via calcium release.
What carries the action potential into the interior of the muscle cell?
T-tubules.
What is a triad in muscle fibers?
A T-tubule flanked by two terminal cisternae of the sarcoplasmic reticulum.
What are the three phases of a muscle twitch?
Latent period, contraction phase, and relaxation phase.
What is wave summation?
Increased muscle tension due to repeated stimulation before complete relaxation.
What is tetanus in muscle contraction?
Sustained contraction without relaxation due to high-frequency stimulation.
What is treppe?
Stepwise increase in contraction strength when a muscle is stimulated after rest.
What is hypertrophy?
Increase in muscle size due to added structural proteins.
What is atrophy?
Decrease in muscle size due to loss of structural proteins.
What is sarcopenia?
Age-related muscle loss.
What are the three muscle fiber types?
Slow oxidative (SO), fast oxidative (FO), and fast glycolytic (FG).
Which fiber type is used in endurance exercise?
Slow oxidative (SO) fibers.
Which fiber type is dominant in resistance training?
Fast glycolytic (FG) fibers.
What is angiogenesis?
Formation of new capillaries in muscle tissue in response to endurance training.
What substance allows brief, intense energy for muscle contraction?
Creatine phosphate.
What performance-enhancing hormone increases red blood cell production?
Erythropoietin (EPO).
What hormone promotes tissue repair and recovery?
Human Growth Hormone (hGH).
What initiates a muscle contraction at the cellular level?
An action potential arriving at the axon terminal of a motor neuron.
What are voltage-gated calcium channels?
Channels that open in response to depolarization, allowing calcium to enter the axon terminal.
What is exocytosis in the context of muscle contraction?
The process of releasing acetylcholine into the synaptic cleft from synaptic vesicles.
What role does the sarcolemma play in muscle contraction?
It propagates the action potential across the muscle fiber.
What happens after sodium influx in the muscle cell?
The membrane depolarizes, triggering an action potential.
What terminates the effect of acetylcholine in the synaptic cleft?
Acetylcholinesterase breaks it down.
Why is calcium essential in excitation-contraction coupling?
It binds to troponin, allowing actin and myosin interaction.
What is the role of T-tubules in muscle contraction?
They transmit the action potential deep into the muscle fiber.
What does the triad structure consist of?
A T-tubule and two terminal cisternae of the sarcoplasmic reticulum.
What occurs during ATP hydrolysis in the contraction cycle?
ATP splits into ADP and Pi, energizing the myosin head.
What is cross-bridge formation?
The binding of myosin heads to actin binding sites.
What is the power stroke?
The pivoting of the myosin head that pulls actin toward the M line.
What causes the myosin head to detach from actin?
Binding of a new ATP molecule.
What happens if stimulation of the muscle stops?
Calcium channels close, and calcium is pumped back into the SR.
What causes muscle relaxation?
Troponin and tropomyosin return to resting position, blocking actin binding sites.
What is the primary cause of muscle hypertrophy?
Increased structural proteins and myofibrils in the muscle fiber.
What is the main source of ATP during endurance exercise?
Aerobic respiration.
What protein stores oxygen in muscle cells?
Myoglobin.
How does endurance training affect mitochondria?
It increases the number of mitochondria in muscle cells.
What is the effect of resistance training on muscle fibers?
Increases muscle fiber diameter and strength.
Why does muscle soreness occur after intense exercise?
Due to microscopic damage to muscle fibers and sarcolemma.
What is the effect of sarcopenia on muscle tissue?
Leads to muscle mass loss and replacement with fat and connective tissue.
What is the function of facial expression muscles?
To manipulate the skin to form expressions.
What are the two main bellies of the occipitofrontalis?
Frontal belly and occipital belly.
What does the frontal belly of the occipitofrontalis do?
Raises the eyebrows and wrinkles the forehead.
What does the occipital belly of the occipitofrontalis do?
Retracts the scalp.
What does the orbicularis oris do?
Closes and purses the lips.
What does the levator labii superioris do?
Raises the upper lip.
What does the zygomaticus major do?
Pulls corners of mouth upward and outward.
What does the risorius do?
Purses lips by drawing corners laterally.
What does the buccinator do?
Compresses cheeks, as in sucking or blowing.
What does the orbicularis oculi do?
Closes the eye.
What does the levator palpebrae superioris do?
Raises the upper eyelid.
What does the corrugator supercilii do?
Wrinkles the skin between the eyebrows.
What is mastication?
Chewing.
What does the masseter do?
Elevates the mandible.
What does the temporalis do?
Elevates and retracts the mandible.
What does the medial pterygoid do?
Moves jaw side to side and assists in opening/closing.
What does the lateral pterygoid do?
Protrudes, depresses, and moves mandible laterally.
What does the genioglossus do?
Depresses and protracts the tongue.
What does the styloglossus do?
Elevates and retracts the tongue.
What does the hyoglossus do?
Flattens and depresses the tongue.
What does the palatoglossus do?
Elevates the back of the tongue.
What does the digastric muscle do?
Depresses the mandible and elevates the hyoid bone.
What does the mylohyoid do?
Raises the floor of the mouth and hyoid.
What does the stylohyoid do?
Elevates and retracts the hyoid.
What does the geniohyoid do?
Pulls the hyoid forward and depresses mandible.
What does the sternohyoid do?
Depresses the hyoid bone.
What does the thyrohyoid do?
Elevates the larynx and depresses the hyoid.
What does the omohyoid do?
Depresses the hyoid and larynx.
What does the sternothyroid do?
Depresses the thyroid cartilage and larynx.
What do suprahyoid and infrahyoid muscles assist with?
Swallowing, tongue movement, and speech.
What is the role of the hyoid bone?
Acts as a base for tongue movement and larynx positioning.
What is the action of the sternocleidomastoid?
Rotates and flexes the neck.
What is the action of the splenius capitis?
Extends and rotates the head.
Which facial muscle compresses the cheeks during sucking?
Buccinator.
Which muscle pulls the eyebrows together?
Corrugator supercilii.
What is the action of the depressor anguli oris?
Pulls corners of the mouth downward.
Which muscle allows closing and pursing of the lips?
Orbicularis oris.
Which muscle is used to raise the upper lip in a sneer?
Levator labii superioris.
Which joint do the muscles of mastication act on?
The temporomandibular joint (TMJ).
Which muscles assist the masseter in chewing?
Temporalis, medial and lateral pterygoids.
What type of movement is produced by the pterygoid muscles?
Side-to-side and protrusion of the jaw.
What are extrinsic tongue muscles responsible for?
Moving the tongue in different directions.
What are intrinsic tongue muscles responsible for?
Changing the shape of the tongue.
What is the origin and insertion of the genioglossus?
Origin: mandible; Insertion: undersurface of tongue and hyoid.
What is the origin and insertion of the styloglossus?
Origin: styloid process of temporal bone; Insertion: sides of tongue.
What is the function of the palatoglossus during swallowing?
Elevates the back of the tongue.
What is the function of the digastric muscle’s anterior belly?
Depresses the mandible.
What is the function of the digastric muscle’s posterior belly?
Elevates and retracts the hyoid bone.
What is the function of the mylohyoid muscle?
Forms the floor of the mouth and elevates it during swallowing.
Where does the geniohyoid originate and insert?
Origin: mandible; Insertion: hyoid bone.
What is the role of the thyrohyoid in vocalization?
Shrinks distance between thyroid cartilage and hyoid to produce high-pitched sounds.
What muscle depresses the thyroid cartilage to change vocal tone?
Sternothyroid.
Which muscle has two bellies and helps retract and depress the hyoid?
Omohyoid.
What is the bilateral action of the sternocleidomastoid?
Flexes the neck forward.
What is the unilateral action of the sternocleidomastoid?
Rotates head to opposite side.
What is the function of the longissimus capitis?
Extends and laterally rotates the head.
Which muscle group supports posture of the neck?
Semispinalis capitis and splenius capitis.
What does ‘mastication’ mean?
Chewing.
What does ‘deglutition’ mean?
Swallowing.
What is the temporomandibular joint (TMJ)?
The joint where the mandible meets the temporal bone, enabling jaw movement.
What does the term ‘glossus’ refer to in muscle names?
It means tongue.
What is the function of the hyoid bone?
It supports tongue movement and anchors muscles involved in swallowing and speech.
Where does the masseter originate and insert?
Origin: maxilla arch and zygomatic arch; Insertion: mandible.
Where does the temporalis originate and insert?
Origin: temporal bone; Insertion: mandible.
Where does the lateral pterygoid originate and insert?
Origin: pterygoid process of sphenoid bone; Insertion: mandible.
Where does the medial pterygoid originate and insert?
Origin: sphenoid bone and maxilla; Insertion: mandible and TMJ.
What is the origin and insertion of the genioglossus?
Origin: mandible; Insertion: tongue undersurface and hyoid bone.
What is the origin and insertion of the styloglossus?
Origin: styloid process of temporal bone; Insertion: tongue undersurface and sides.
What is the origin and insertion of the hyoglossus?
Origin: hyoid bone; Insertion: sides of tongue.
What is the origin and insertion of the palatoglossus?
Origin: soft palate; Insertion: side of tongue.
What does the digastric muscle do during swallowing?
Raises the hyoid and larynx and depresses the mandible.
What is the origin and insertion of the digastric muscle?
Origin: mandible and temporal bone; Insertion: hyoid bone.
Where does the stylohyoid originate and insert?
Origin: styloid process of temporal bone; Insertion: hyoid bone.
Where does the mylohyoid originate and insert?
Origin: mandible; Insertion: hyoid bone and median raphe.
Where does the geniohyoid originate and insert?
Origin: mandible; Insertion: hyoid bone.
What is the action of the sternohyoid?
Depresses the hyoid during swallowing and speaking.
Where does the sternohyoid originate and insert?
Origin: clavicle; Insertion: hyoid bone.
Where does the sternothyroid originate and insert?
Origin: sternum; Insertion: thyroid cartilage.
Where does the thyrohyoid originate and insert?
Origin: thyroid cartilage; Insertion: hyoid bone.
Where does the omohyoid originate and insert?
Origin: scapula; Insertion: hyoid bone.
What muscle presses the tongue against the roof of the mouth to push food back?
Mylohyoid.
Which muscles raise the larynx during swallowing?
Digastric, stylohyoid, and geniohyoid.
Which muscles depress the larynx to alter vocal pitch?
Sternothyroid and omohyoid.
Which muscles control the position of the larynx for speech and breathing?
Infrahyoid muscles.
What are the two main groups of neck muscles?
Flexors and extensors.
What happens when neck muscles contract bilaterally?
The head flexes or extends.
What happens when neck muscles contract unilaterally?
The head rotates or laterally flexes.
What is the main action of the sternocleidomastoid muscle when acting bilaterally?
Flexes the neck.
What is the unilateral action of the sternocleidomastoid?
Draws the head to the same shoulder.
What are the three scalene muscles?
Anterior, middle, and posterior scalene muscles.
What is the function of the scalene muscles?
Flex, laterally flex, and rotate the cervical vertebrae.
What additional role do scalene muscles play besides moving the neck?
Assist in deep inhalation.
What are the primary extensor muscles of the neck?
Splenius capitis, splenius cervicis, and semispinalis capitis.
Where does the splenius capitis insert?
Onto the temporal and occipital bones.
Where does the splenius cervicis insert?
Onto the cervical vertebrae.
What is the action of the splenius capitis when acting bilaterally?
Extends the neck.
What is the action of the splenius capitis when acting unilaterally?
Laterally flexes and rotates the head.
What is the bilateral action of semispinalis capitis?
Extends the neck.
What is the unilateral action of semispinalis capitis?
Rotates the head to the opposite side.
What muscle rotates and tilts the head backward?
Longissimus capitis.
Where does the longissimus capitis insert?
On the mastoid process of the temporal bone.
Which neck muscles rotate the head to the opposite side?
Sternocleidomastoid and semispinalis capitis.
Which neck muscles rotate the head to the same side?
Splenius capitis, splenius cervicis, and longissimus capitis.
Which neck muscle group is located deep in the side of the neck?
Scalene muscles.
What distinguishes the middle scalene from the others?
It is the longest of the scalene muscles.
Which muscle divides the neck into anterior and posterior triangles?
Sternocleidomastoid.
What are the three groups of muscles in the back?
Erector spinae, transversospinalis, and superficial muscles.
What is another name for the erector spinae?
Sacrospinalis or extensor spinae.
What is the function of the erector spinae group?
Extends, laterally flexes, and rotates the vertebral column.
What are the three sections of the erector spinae?
Iliocostalis, longissimus, and spinalis.
Where is the iliocostalis group located?
Laterally in the back.
Where is the longissimus group located?
Intermediately in the back.
Where is the spinalis group located?
Medially in the back.
What is the action of the iliocostalis cervicis?
Extends, laterally flexes, and rotates the vertebral column.
What is the action of the iliocostalis thoracis?
Extends and laterally flexes the thoracic spine.
What is the action of the iliocostalis lumborum?
Extends and laterally flexes the spine.
What is the action of the longissimus capitis?
Extends the head and turns the face to the same side.
What is the action of the longissimus cervicis?
Extends and laterally flexes the cervical spine.
What is the action of the longissimus thoracis?
Extends and laterally flexes the thoracic spine.
What are the muscles in the spinalis group?
Spinalis capitis, spinalis cervicis, and spinalis thoracis.
What is the action of spinalis capitis?
Extends the head and turns the face toward the opposite side.
What is the action of spinalis cervicis?
Extends the cervical spine.
What is the action of spinalis thoracis?
Extends the thoracic spine.
What are the two main parts of the transversospinalis group?
Semispinalis and multifidus.
Where do transversospinalis muscles attach?
From transverse processes to spinous processes of vertebrae.
What is the action of semispinalis capitis?
Extends the head and rotates it to the opposite side.
What is the action of semispinalis cervicis?
Extends and rotates the cervical spine to the opposite side.
What is the action of semispinalis thoracis?
Extends and rotates the thoracic spine to the opposite side.
What is the function of the multifidus?
Extends, laterally flexes, and rotates the vertebral column.
What are the two superficial muscles of the back?
Serratus posterior superior and serratus posterior inferior.
What is the action of the serratus posterior superior?
Elevates the ribs.
What is the action of the serratus posterior inferior?
Pulls the ribs downward and backward.
What are the four abdominal muscle groups?
External obliques, internal obliques, transversus abdominis, rectus abdominis.
What is the action of the rectus abdominis?
Flexes the vertebral column and increases intra-abdominal pressure.
What is the function of the external and internal obliques?
Flex and rotate the vertebral column, increase intra-abdominal pressure.
What is the action of the transversus abdominis?
Compresses the abdominal cavity.
What muscle helps with posture and lateral flexion of the spine?
Quadratus lumborum.
What is the linea alba?
A fibrous band that connects the bilateral rectus sheaths at the anterior midline.
What are tendinous intersections?
Transverse bands of collagen fibers segmenting the rectus abdominis.
What are the main muscles of respiration?
Diaphragm and intercostal muscles.
What are the three types of intercostal muscles?
External, internal, and innermost intercostals.
What is the function of the external intercostals?
Raise the rib cage during inspiration.
What is the function of the internal intercostals?
Lower the rib cage during expiration.
What is the function of the innermost intercostals?
Assist internal intercostals in forced expiration.
What is the diaphragm?
A dome-shaped muscle that separates the thoracic and abdominal cavities.
What happens when the diaphragm contracts?
It flattens and increases thoracic cavity volume.
What are the three parts of the diaphragm?
Sternal, costal, and lumbar.
What is the central tendon of the diaphragm?
The insertion point for diaphragm muscle fibers.
What three structures pass through the diaphragm?
Inferior vena cava, esophagus, and aorta.
What is the Valsalva maneuver?
A cooperative contraction of the diaphragm and abdominal muscles for activities like defecation.
What are the major muscles of the pelvic diaphragm?
Levator ani and ischiococcygeus.
What muscles make up the levator ani?
Pubococcygeus and iliococcygeus.
What is the function of the levator ani?
Supports pelvic viscera and forms anal and urethral sphincters.
What is the function of the ischiococcygeus?
Pulls the coccyx anteriorly and supports pelvic organs.
Which muscles are in the deep layer of the male pelvic floor?
Levator ani and coccygeus.
Which muscle forms the anal sphincter in males?
Levator ani.
What are the middle layer muscles in the male pelvic floor?
Deep transverse perineal, sphincter urethrae, and external anal sphincter.
What is the action of the sphincter urethrae?
Voluntarily compresses the urethra and assists in ejaculation.
What are the superficial muscles in the male pelvic floor?
Ischiocavernosus, bulbospongiosus, and superficial transverse perineal muscle.
What openings does the female pelvic floor have?
Vagina, urethra, and anus.
What is the function of the ischiocavernosus in females?
Helps maintain clitoral erection.
What is the action of the bulbospongiosus in females?
Compresses the vestibular bulb and constricts the vaginal orifice.
What do superficial transverse perineal muscles do?
Anchor the perineal body, supporting the pelvic floor.
What are the primary functions of the muscles of the upper limb?
To reach, pick up, and manipulate objects.
What do intrinsic hand muscles assist with?
Precise movements such as typing or writing.
Which muscles position the pectoral girdle from the anterior thorax?
Subclavius, pectoralis minor, serratus anterior.
Which muscles position the pectoral girdle from the posterior thorax?
Trapezius, rhomboid major, rhomboid minor.
What is the action of the serratus anterior?
Protracts the scapula and pectoral girdle.
What is the action of the trapezius?
Elevates and retracts the scapula, depresses its medial aspect, and extends the head and neck.
Which muscles are axial movers of the humerus?
Pectoralis major and latissimus dorsi.
What is the action of pectoralis major?
Adducts and internally rotates the humerus, flexes or extends the shoulder.
What is the action of latissimus dorsi?
Extends, adducts, and medially rotates the arm.
What four muscles make up the rotator cuff?
Supraspinatus, infraspinatus, teres minor, subscapularis.
What is the action of supraspinatus?
Initiates abduction of the arm.
What is the action of infraspinatus and teres minor?
Laterally rotate the arm.
What is the action of subscapularis?
Medially rotates the arm.
What is the action of the deltoid?
Abducts the shoulder and assists with flexion, extension, and rotation.
What is the action of the coracobrachialis?
Flexes and adducts the arm.
What muscles flex the forearm?
Biceps brachii, brachialis, brachioradialis.
Which arm muscle also supinates the forearm?
Biceps brachii.
What is the action of the triceps brachii?
Extends the elbow and adducts the arm.
What muscles are in the superficial posterior compartment of the forearm?
Extensor carpi radialis longus/brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris.
Name the deep posterior compartment forearm muscles.
Abductor pollicis longus, extensor pollicis brevis/longus, extensor indicis.
What is the function of extensor digitorum?
Extends the wrist and fingers 2–5.
What are the deep anterior flexors of the forearm?
Flexor digitorum profundus and flexor pollicis longus.
What is the function of flexor digitorum superficialis?
Flexes fingers 2–5 at the knuckles.
What are the thenar muscles and their function?
Abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, adductor pollicis — act on the thumb.
What are the hypothenar muscles and their function?
Abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi — act on the little finger.
What are the mid palmar muscles and their function?
Lumbricals, palmar interossei, dorsal interossei — flex, extend, adduct, and abduct fingers.
What compartments exist in the upper limb?
Superficial and deep flexors, superficial and deep extensors of arm and forearm.
What are septa in muscle anatomy?
Sheet-like structures that subdivide muscle compartments.
What are the main regions of muscles in the lower limb?
Hip, thigh, leg, and foot.
What are the three main muscle groups of the hip?
Flexors, gluteals, and lateral rotators.
Which compartment of the leg contains dorsiflexors?
Anterior compartment.
Where are plantar flexors of the toes located?
On the sole (plantar surface) of the foot.
What muscles make up the iliopsoas group?
Psoas major and iliacus.
What is the action of the iliopsoas group?
Flexes the thigh at the hip, rotates it laterally, and flexes the trunk.
Which muscles are in the gluteal group?
Gluteus maximus, gluteus medius, gluteus minimus.
What is the primary action of the gluteus maximus?
Extension of the femur.
What is the primary action of gluteus medius and minimus?
Abduction of the thigh.
What muscles make up the quadriceps femoris group?
Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius.
What is the common action of the quadriceps muscles?
Extension of the knee.
What is the longest muscle in the body?
Sartorius.
What is the action of the sartorius?
Flexes the hip and knee and rotates the femur.
What muscles make up the hamstring group?
Biceps femoris, semitendinosus, semimembranosus.
What is the action of the hamstrings?
Flex the knee and extend the hip.
Which muscles adduct the thigh?
Adductor longus, adductor brevis, adductor magnus, gracilis, pectineus.
Which medial thigh muscle also flexes the knee?
Gracilis.
Name three lateral rotators of the hip.
Piriformis, obturator internus, quadratus femoris.
Which muscles are in the posterior superficial leg compartment?
Gastrocnemius, soleus, plantaris.
What is the action of gastrocnemius and soleus?
Plantarflex the ankle.
What deep posterior leg muscles assist in foot inversion?
Tibialis posterior, flexor digitorum longus, flexor hallucis longus.
What is the action of flexor hallucis longus?
Flexes the big toe.
Which muscle assists knee rotation and is in the deep posterior compartment?
Popliteus.
What is the primary action of tibialis anterior?
Dorsiflexes the ankle and inverts the foot.
What muscles extend the toes in the anterior leg?
Extensor digitorum longus, extensor hallucis longus.
What lateral leg muscles evert the foot?
Fibularis longus and fibularis brevis.
Which muscle extends toes 2–4 on the dorsum of the foot?
Extensor digitorum brevis.
What is the action of extensor hallucis brevis?
Extends the hallux (big toe).
What muscles are found in the plantar layer 1?
Abductor hallucis, abductor digiti minimi, flexor digitorum brevis.
What are the thigh compartments?
Anterior, medial, posterior.
What are the leg compartments?
Anterior, lateral, posterior deep, posterior superficial.
What anatomical structures separate compartments?
Septa (sheet-like fascia).
