Skeletal Muscle Structure and Sarcomeres
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Questions and Answers

Which of the following muscles would be considered a synergist to the biceps brachii during elbow flexion?

  • Brachialis (correct)
  • Pectoralis major
  • Deltoid
  • Triceps brachii

What type of muscle contraction occurs when the muscle shortens, causing movement?

  • Eccentric
  • Isometric
  • Isokinetic
  • Concentric (correct)

What is the primary role of ligaments in the skeletal system?

  • Connecting bone to bone (correct)
  • Providing cushioning between bones
  • Generating movement
  • Connecting muscle to bone

Which type of bone is characterized by its long, cylindrical shape and is responsible for providing support and movement?

<p>Long (D)</p> Signup and view all the answers

What role do fixator muscles play during movement?

<p>They stabilize the body to allow for efficient movement. (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of an ataxic gait?

<p>Stiffness and rigidity in the joints (A)</p> Signup and view all the answers

In a hemiplegic gait, which of the following movements is typically observed in the affected upper limb?

<p>Flexion, adduction, and internal rotation (D)</p> Signup and view all the answers

Parkinsonian gait is primarily caused by dysfunction in which part of the nervous system?

<p>Basal ganglia (A)</p> Signup and view all the answers

Which muscle is primarily responsible for causing the Trendelenburg sign when standing on one leg?

<p>Gluteus medius and minimus (B)</p> Signup and view all the answers

What is the primary characteristic of the Trendelenburg gait?

<p>Excessive hip swing or wobbling (C)</p> Signup and view all the answers

Which of the following is NOT a subphase of the stance phase of gait?

<p>Swing phase (D)</p> Signup and view all the answers

What is the primary characteristic of an antalgic gait?

<p>Shorter stance phase for the injured limb (A)</p> Signup and view all the answers

Which of the following factors can affect the gait pattern of an individual?

<p>All of the above (D)</p> Signup and view all the answers

What is the primary difference between an antalgic gait and an arthrogenic gait?

<p>Antalgic gait is caused by pain, while arthrogenic gait is caused by abnormal joint motion. (B)</p> Signup and view all the answers

What does a decreased walking velocity and stride length typically suggest in gait analysis?

<p>Bilateral limb involvement (D)</p> Signup and view all the answers

What is the purpose of conducting a gait analysis?

<p>All of the above (D)</p> Signup and view all the answers

Which of the following body systems does NOT play a role in gait?

<p>Endocrine system (C)</p> Signup and view all the answers

What is the primary function of the swing phase of gait?

<p>To lift the foot off the ground and advance it forward (B)</p> Signup and view all the answers

What is the primary role of calcium ions in the body?

<p>Muscle contractions and nerve impulse transmission (D)</p> Signup and view all the answers

Which type of movement increases the angle between articulating bones?

<p>Extension (B)</p> Signup and view all the answers

In which plane do abduction and adduction typically occur?

<p>Frontal plane (B)</p> Signup and view all the answers

What characterizes the circumduction movement?

<p>Movement of the distal end of a body part in a circle (C)</p> Signup and view all the answers

What does 'gait analysis' primarily evaluate?

<p>Normal and abnormal gait mechanics (B)</p> Signup and view all the answers

What is a common limitation of clinical analysis in assessing musculoskeletal injuries?

<p>Inability to observe the patient in motion (A)</p> Signup and view all the answers

Which joint classification allows for free movement?

<p>Synovial joints (C)</p> Signup and view all the answers

What type of tissue is primarily found in yellow bone marrow?

<p>Adipose tissue (D)</p> Signup and view all the answers

What position should your body be in during the load phase of jumping?

<p>Balanced on the balls of your feet with knees slightly flexed (A)</p> Signup and view all the answers

Which of the following best describes qualitative analysis methods?

<p>Evaluation based on direct observation and subjective measures (D)</p> Signup and view all the answers

What is one of the steps included in both qualitative and quantitative methods of analysis?

<p>Adopting a definite observational plan (A)</p> Signup and view all the answers

In qualitative analysis, what is a primary cause of performance deficiencies?

<p>Errors in technique, perception, or decision-making (D)</p> Signup and view all the answers

Which of the following is NOT a step in the quantitative analysis process?

<p>Visual observation without data collection (B)</p> Signup and view all the answers

What tactic is recommended during the pre-observation phase of skill analysis?

<p>Developing a model of the skill to be analyzed (B)</p> Signup and view all the answers

Which phase of analysis relies primarily on visual observation?

<p>Qualitative analysis (C)</p> Signup and view all the answers

Which of the following aspects is NOT essential in qualitative analysis?

<p>Collecting and analyzing numerical data (D)</p> Signup and view all the answers

What is the primary role of tendons in the body?

<p>Connect muscle to bone, transmitting force. (A)</p> Signup and view all the answers

What structural component gives bones both strength and flexibility?

<p>The combination of calcium and collagen. (B)</p> Signup and view all the answers

What is the primary function of red bone marrow?

<p>Producing blood cells. (C)</p> Signup and view all the answers

Which type of marrow is primarily responsible for storing fat?

<p>Yellow marrow (C)</p> Signup and view all the answers

Which of the following pairs is NOT a correct association in the musculoskeletal system?

<p>Cartilage - responsible for blood cell production (B)</p> Signup and view all the answers

How does the skeletal system contribute to protecting internal organs?

<p>By absorbing impact and distributing force. (C)</p> Signup and view all the answers

If a person develops anemia, what might happen to their yellow bone marrow?

<p>It would transform into red bone marrow. (B)</p> Signup and view all the answers

What is the main function of the axial skeleton?

<p>Supporting and protecting internal organs. (D)</p> Signup and view all the answers

Flashcards

Synergists

Muscles that perform, or assist in performing, the same joint motion as the prime movers (agonists). They help control and refine the movement.

Fixators

Muscles that stabilize the body to help with the movement of another muscle. They prevent unwanted movements.

Concentric Contraction

Muscle contraction where the muscle shortens and causes movement. Think of lifting a weight.

Eccentric Contraction

Muscle contraction where the muscle lengthens while producing force. Think of lowering a weight.

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Ligaments

Connective tissue that joins bone to bone. They provide stability and limit joint movement.

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Joint

A point of contact between two bones, between bone and cartilage, or between bone and teeth.

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Flexion

Movement where the angle between articulating bones decreases. Think bringing your arm towards your body.

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Extension

Movement where the angle between articulating bones increases. Think straightening your arm.

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Hyperextension

Movement where the angle between articulating bones is extended beyond its normal range. Think bending your head back.

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Circumduction

Movement where the distal end of a body part moves in a circle. Think drawing a circle with your arm.

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Rotation

A bone revolves around its own longitudinal axis. Think twisting your hand.

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Synovial Joint

A structural classification of joints that allows for free movement. Think shoulder or hip.

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Movement Analysis

The analysis of movement through sensor signals, often involving gait analysis.

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Qualitative analysis

Methods of analysis that use non-numerical descriptions to evaluate a skill during direct observation.

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Observational plan (Qualitative)

A plan for observing a skill with multiple views and focus on specific movements.

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Visual mental image (Qualitative)

The process of developing a visual mental image of a skill's performance from observations.

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Pre-observation phase (Qualitative)

A pre-observation phase where a model of the skill is created and essential mechanical variables are identified.

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Quantitative analysis

Methods of analysis that involve collecting, measuring, and evaluating numerical data from an activity.

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Pre-observation stage (Quantitative)

The stage where the goals, important variables, and acceptable ranges are determined before collecting data.

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Critical variables (Quantitative)

The variables that are critical to the performance and are measured in quantitative analysis.

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Acceptable range (Quantitative)

The range of acceptable values for the measured variables during quantitative analysis.

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What is a tendon?

Tendon is a tough, fibrous connective tissue. It connects muscles to bones, transferring force for movement.

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What are ligaments?

Ligaments are strong, flexible bands of tissue that connect bones to other bones at joints, providing stability and limiting movement.

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What is the musculoskeletal system?

The muscular and skeletal systems work together to allow movement. Muscles contract and pull on bones, causing them to move or stabilize.

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What is the protective function of the skeleton?

The skeleton protects vital organs by surrounding them with strong bone tissue, absorbing impacts and preventing damage.

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What is bone marrow and what is its role?

Bone marrow is a spongy tissue inside bones that produces blood cells, including red blood cells for oxygen transport and some white blood cells.

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What is the function of red bone marrow?

Red bone marrow produces red blood cells and many white blood cells, essential for oxygen transport and immune defenses.

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What is the function of yellow bone marrow?

Yellow bone marrow primarily stores fat, but can convert to red bone marrow if needed for increased blood cell production.

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How does bone tissue contribute to mineral storage?

Bones act as a storage reservoir for minerals like calcium and phosphorus, releasing them into the bloodstream to maintain essential levels for vital functions.

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Ataxic Gait

A gait characterized by wide steps and jerky, irregular, uncoordinated movements. It's often caused by problems in the cerebellum, the part of the brain responsible for balance and coordination.

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Hemiplegic Gait

A gait where one leg swings outward in a circular motion to move forward. It's caused by weakness on one side of the body, often seen in stroke patients.

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Parkinsonian Gait

A gait characterized by slow, shuffling steps and a stooped posture. It's caused by rigidity in the joints and slow movement, often seen in Parkinson's disease.

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Trendelenburg Gait

A gait where the pelvis drops on the side opposite the stance leg. It's caused by weakness in the gluteus medius and minimus muscles, which are important for stabilizing the pelvis.

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Trendelenburg Sign

A sign where the pelvis drops towards the floor when standing on one leg. Indicates weakness in the gluteus medius and minimus muscles.

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Stance Phase

The period of the gait cycle when the foot is on the ground and bearing weight.

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Swing Phase

The period of the gait cycle when the foot is not in contact with the ground.

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Gait

The act of walking, involving the coordinated movements of joints and muscles.

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Gait Pattern

A gait analysis to assess and describe gait characteristics.

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Antalgic Gait

A shorter stance phase for the injured limb and a shorter swing phase for the uninjured limb, often seen due to injury or pain.

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Arthrogenic Gait

An abnormal gait seen due to abnormal joint motion, which may or may not be accompanied by pain.

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Gait Disorders

Variations from typical gait patterns due to factors like age, injury, or neurological disorders.

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Clinical Gait Analysis

A detailed assessment of someone's gait, using tools and observation, to identify any abnormalities.

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Study Notes

Skeletal Muscle Structure

  • Skeletal muscle is composed of fascicles, which are bundles of muscle fibers.
  • Muscle fibers are individual muscle cells.
  • Each muscle fiber contains myofibrils, which are bundles of protein filaments.
  • Myofibrils are composed of thick filaments (myosin) and thin filaments (actin).
  • The arrangement of these filaments creates repeating units called sarcomeres.
  • Sarcomeres are the functional units of muscle contraction.

Components of a Sarcomere

  • Z discs are plate-shaped regions that separate one sarcomere from the next.
  • A band contains thick filaments and includes parts of thin filaments overlapping thick filaments.
  • I band is lighter, less dense area, containing parts of thin filaments but no thick filaments.
  • H zone is a narrow region in the center of A band that contains thick filaments but no thin filaments.
  • M line is a region in the center of H zone that contains proteins holding thick filaments together.

Skeletal Muscle Fiber Proteins

  • Contractile proteins (myosin and actin) generate force during muscle contractions.
  • Myosin is a thick filament protein with a tail and myosin heads that bind to actin.
  • Actin is a thin filament protein with myosin-binding sites.
  • Regulatory proteins (tropomyosin and troponin) control the muscle contraction process.
  • Tropomyosin covers myosin-binding sites on actin molecules in relaxed muscles.
  • Calcium ions binding to troponin change its shape, moving tropomyosin and allowing contraction.
  • Structural proteins (titin, α-actinin, myomesin, nebulin, and dystrophin) maintain the organization and stability of myofibrils.
  • Titin links the Z disc to the M line and contributes to muscle elasticity.

Muscle Contraction and Relaxation

  • Muscle contraction involves the sliding of actin and myosin filaments.
  • ATP is needed for myosin heads to detach from actin and re-energize for another power stroke.
  • Calcium ions are released from the sarcoplasmic reticulum to initiate contraction.
  • Relaxation occurs when calcium ions are pumped back into the sarcoplasmic reticulum, causing tropomyosin to cover myosin-binding sites on actin.

Muscle Fiber Types

  • Muscle fibers are classified into Type I (oxidative), Type IIa (oxidative-glycolytic), and Type IIb (fast-glycolytic) based on their structural and functional differences.
  • Type I fibers are slow-twitch, fatigue-resistant, and have high aerobic capacity.
  • Type IIa fibers are fast-twitch, fatigue-resistant, and have both aerobic and anaerobic capacities.
  • Type IIb fibers are fast-twitch, fatigue-prone, and have high anaerobic capacity.

Muscle Function

  • Agonists cause movement.
  • Antagonists act in opposition to movement.
  • Synergists assist in movement.
  • Fixators stabilize body parts during movement.

Types of Muscle Contractions

  • Isometric contractions involve no change in muscle length.
  • Isotonic contractions involve a change in muscle length (concentric-shortening, eccentric-lengthening).

Skeletal System

  • Bones are connected by tendons and ligaments.
  • Bones are classified into long, short, flat, irregular, and sesamoid types.
  • Cartilage reduces friction between bones.
  • Bone tissue is vital for mineral storage and blood cell production.

Joint Types

  • Fibrous joints are immovable or slightly movable.
  • Cartilaginous joints have cartilage between bones.
  • Synovial joints are freely movable, contain a synovial cavity, and have articular cartilage.

Planes of Movement

  • Transverse, Sagittal, and Frontal planes are the reference points for movements in the body.

Movement Analysis

  • Movement analysis encompasses different methods for examining movement, including qualitative (subjective) and quantitative (objective) methods.
  • Qualitative analysis involves non-numerical evaluation of movement, focusing on the quality of the movement.
  • Quantitative analysis involves numerical measurement of movement, including pre-observation (model of skill, variables) and observational steps (identification, selection of variables, acceptable range).

Gait

  • Gait is the action of walking (locomotion).
  • Gait is a complex, whole-body movement, requiring coordinated action of many joints and muscles.
  • Phases of gait include stance and swing phases.
  • Gait patterns are influenced by several individual variables (e.g., age, height, weight, sex, walking speed, strength, flexibility, aerobic conditioning).
  • Gait disorders can alter distance and time variables, stride length, and swing-stance ratios.

Jumping

  • Jumping involves three phases (load, flight, and landing).
  • The load phase involves balancing the body on the balls of the feet, with slightly flexed knees.

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PSG 205 a-1 PDF - Muscle Physiology

Description

Explore the intricate structure of skeletal muscles and their functional units, the sarcomeres. This quiz covers the composition of muscle fibers, myofibrils, and the organization of various zones within a sarcomere. Test your understanding of muscle anatomy and contraction mechanisms.

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