Biomechanics and Levers Quiz
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Questions and Answers

What is the primary role of synovial fluid in the joints?

  • Reducing the range of motion
  • Providing structural support to the bones
  • Transporting nutrients and waste (correct)
  • Increasing bone density
  • Which structures make up the shoulder girdle?

  • Scapula and clavicle (correct)
  • Humerus and ribs
  • Humerus and scapula
  • Clavicle and ribs
  • What proportion of rotation occurs in the shoulder girdle for every 2° of glenohumeral abduction?

  • (correct)
  • 1.5°
  • What is the role of the glenoid labrum in the glenohumeral joint?

    <p>Providing stability by deepening the socket</p> Signup and view all the answers

    What is the strength-to-balance ratio between internal and external rotators?

    <p>3:2</p> Signup and view all the answers

    Which of the following movements is NOT associated with the glenohumeral joint?

    <p>Translation</p> Signup and view all the answers

    What effect does trunk extension have on shoulder flexion?

    <p>It enhances shoulder flexion</p> Signup and view all the answers

    What is the relationship between active and passive range of motion?

    <p>Passive ROM is always greater than active ROM</p> Signup and view all the answers

    What type of joint is the Humeroulnar joint classified as?

    <p>Synovial/Hinge/Diarthrotic/Uniaxial</p> Signup and view all the answers

    Which ligament stabilizes the elbow by preventing radial head rotation against the ulna?

    <p>Annular Ligament</p> Signup and view all the answers

    Which movement is associated with the Proximal Radioulnar Joint?

    <p>Supination/Pronation</p> Signup and view all the answers

    What is the primary function of the Radial Collateral Ligament at the elbow?

    <p>To provide stability against inner to outer stress</p> Signup and view all the answers

    How many synovial joints are part of the elbow complex?

    <p>Three</p> Signup and view all the answers

    Which statement about the Humeroradial joint is accurate?

    <p>It is a synovial/plane joint</p> Signup and view all the answers

    What is true regarding the normal range of motion for shoulder flexion?

    <p>150-180°</p> Signup and view all the answers

    What type of movement does the Ulna Collateral Ligament primarily assist in providing?

    <p>Stability against valgus stress</p> Signup and view all the answers

    What is the primary function of the meniscus in the knee joint?

    <p>Provide lubrication and shock absorption</p> Signup and view all the answers

    What does the screw home mechanism describe in the knee joint?

    <p>The locking of the knee during full extension</p> Signup and view all the answers

    Which factor significantly affects patella tracking during knee movement?

    <p>Location of the tibial tuberosity</p> Signup and view all the answers

    What is the normal Q-angle range for females?

    <p>10-19°</p> Signup and view all the answers

    What happens to the patella during flexion of the knee?

    <p>It moves medially and lies within the intercondylar notch</p> Signup and view all the answers

    What is a consequence of an imbalance in the vastus medialis muscle?

    <p>Lateral patella tracking</p> Signup and view all the answers

    What is one of the key benefits of the patella in the knee joint?

    <p>It reduces friction between the quadriceps and femur</p> Signup and view all the answers

    What would be the likely outcome of a torn meniscus during knee extension?

    <p>Absence of the screw home mechanism</p> Signup and view all the answers

    Study Notes

    Levers

    • First Class: Load → Fulcrum → Effort; Advantage: Force + Distance
    • Second Class: Effort → Load → Fulcrum; Advantage: Force
    • Third Class: Fulcrum → Effort → Load; Advantage: Distance
    • If unsure, assume Third Class.

    Basic Movement Analysis Rules

    • Action + Concentric = Muscle Group (e.g., flexion + concentric = flexors)
    • Action + Eccentric = Muscle Group (e.g., flexion + eccentric = extensors)
    • Isometric = Muscle group working against gravity

    Bone Remodeling

    • Wolff's Law: Bone responds to stress.
    • Examples: Increased humerus width in tennis players, larger metatarsals/tarsals/phalanges in ballet dancers.
    • Bone resorption: Bone breakdown.
    • Example: Reduced bone density in astronauts due to lack of gravity.
    • Adult bone maintenance stage lasts 7-10 years.

    Biomechanics of Bone

    • Loading Modes & Descriptions:
      • Tension: Pulled at ends, elongates (e.g., Calcaneal tensile fracture)
      • Compression: Gravity puts pressure on body, widens in the middle (e.g., vertebral compressive fracture)
      • Shear: Horizontally opposing forces (e.g., leg extension machine)
      • Torsion: Twisting, fracture line diagonal; (e.g., 3-point or 4-point fracture of the tibia)
      • Bending: 3-point or 4-point fracture, (e.g., 3-point tendon fracture of the tibia)
    • Muscle Activity Influence on Bone Loading:
      • Tibia falling forward
      • Ski boot in the way
      • 3 point bending
      • Bone is weaker under compression
      • Soleus muscles compress the tibia
      • Reduces damage in falls

    Bones and Articulations of the Shoulder Complex

    • Shoulder Girdle: Scapula + clavicle (sternoclavicular + acromioclavicular)
    • Movements: Protraction/Retraction, Elevation/Depression, Upward/Downward Rotation
    • Scapulo-humeral Rhythm: 2º glenohumeral abduction = 1º of upward scapular rotation
    • Glenohumeral Joint: Scapula + humerus
    • Movements: Flexion/Extension, Adduction/Abduction, Horizontal abduction/adduction, Internal/External rotation, Circumduction
    • Glenoid Labrum: Fibrocartilage, increases glenoid depth by 50%

    Strength to Balance Ratio Between Internal and External Rotators

    • 3:2 ratio (internal: external)
    • Rotators: Infraspinatus, Teres Minor, Supraspinatus, Subscapularis, Deltoid.

    Shoulder Girdle Actions

    • Elevation/Depression
    • Retraction/Protraction
    • Upward/Downward Rotation

    Spinal Contributions to Shoulder Movement

    • Trunk extension & flexion
    • Lateral flexion & rotation

    Range of Motion (ROM)

    • Flexibility of a joint
    • Measured in degrees using a goniometer.
    • Active ROM: Muscle contraction
    • Passive ROM: External force

    The Elbow Complex

    • Synovial joints:
      • Humeroulnar: Hinge
      • Humeroradial: Plane
      • Proximal Radioulnar: Pivot
    • Ligaments: Annular, Radial collateral, Ulnar collateral
    • Valgus: Distal end of limb more lateral
    • Varus: Distal end of limb more medial

    The Wrist

    • Triangular Fibrocartilage Complex (TFCC): Load-bearing structure, pulley for wrist movements
    • Wrist Movements: Flexion, extension, abduction, adduction
    • Palmar Intercarpal Ligament, Ulnotriquetral, Radiocarpal.
    • Arches of the hand are Proximal Transverse (carpals to metacarpals), Distal Transverse (Metacarpals to phalanges), Longitudinal.

    Carpal Tunnel

    • Retinaculum completes tunnel
    • Median nerve involved
    • Phalen's Test: Wrist flexion for 30-60 seconds
    • Prehension: Grasping objects (Power grip, Pinch grip)

    Pelvis, Hip and Knee

    • Acetabular Labrum: Cartilage ring that deepens the acetabulum.
    • Transverse ligament: Stabilizes hip.
    • Ligamentum Teres: Intra-articular structure, supports & lubricates hip joint.
    • Acetabular alignment: Centre-edge (Wiberg) angle; acetabular anteversion angle
    • Hip extension and internal rotation will tighten the ligaments
    • Types of prehension are Tip pinch, Lateral pinch, Pulp pinch, Palmar pinch

    Active Range of Motion (ROM)

    • Hip Flexion: Supine position, to prevent hamstring stretch.
    • Hip Hyperextension: Supine position, keep knee joint extended, avoid lumbosacral motion

    Assessing Leg Length Discrepancy

    • True leg length: Bone length measured using anterior superior iliac spine (ASIS) and medial malleolus (MM).
    • Apparent leg length: Pelvic rotation, sacroiliac dysfunction, foot pronation/supination
    • Measure from umbilicus to medial malleolus

    Surface Motion of the Knee

    • Sagittal plane motion (flexion & extension):
    • Example: flexion 15 degrees

    Patella Mechanism

    • Functions: Protection, leverage, shock absorption, reducing friction
    • Tracking: Medial/lateral tracking in flexion

    Foot and Ankle

    • Windlass mechanism: Plantarflexion increases arch height.
    • Gait cycle:
      • Stance Phase: Heel strike, foot flat, heel rise, push off, toe off
      • Swing Phase: Acceleration, toe clearance

    Biomechanical Assessment of Foot and Ankle

    • Knee to wall test assesses dorsiflexion ROM

    Spine and Posture

    • Ligaments: Anterior longitudinal ligament, Posterior longitudinal ligament, Ligamentum flavum,.
    • Spinal curvatures: Normal (lordosis, kyphosis) & Abnormal (hypo/hyperlordosis, hypo/hyperkyphosis)
    • Normal line of gravity passes anterior to spinal column if kyphosis exists

    Pelvic Tilt

    • Anterior tilt increase load on lumbar spine.
    • Erector spinae control posture.
    • Lying down and raising legs helps reduce load.

    Spinal Nerves

    • Nerve plexus: 5 main (Cervical, Brachial, Lumbar, Sacral, Coccygeal)
    • Spinal nerves: 31 pairs total

    Spinal Nerve Diagram

    • Dorsal root: Sensory neurons
    • Ventral root: Motor neurons
    • Reflex arc: Unconscious response loop.

    Components of a Reflex Arc

    • Receptor: Receives stimulus
    • Sensory neuron: Transmits signal
    • Integration centre: Relays signal
    • Motor neuron: Carries signal to effector
    • Effector: Carries out response

    Brachial Plexus

    • Spinal nerves C5-T1 (superior to clavicle).
    • Innervates upper limbs and associated dermatomes.

    Lumbar Plexus

    • Spinal nerves L1-L4
    • Innervates anterior and medial thigh, associated dermatomes
    • Also innervates some hip muscles

    Sacral Plexus

    • Spinal nerves L4-S4
    • Longest, thickest plexus
    • Pain along sciatic nerve, possible numbness/shooting pain/leg pain.

    Innervation of Skin

    • Dermatomes: Areas of skin innervated by a specific spinal nerve.

    Somatotyping

    • Quantifies body shape and composition.
      • Endomorphy: Fatness
      • Mesomorphy: Musculoskeletal robustness
      • Ectomorphy: Linearity/slenderness

    Measuring Somatotypes – Heath Carter Method

    • Body measurements for somatotyping (height, weight, skin folds, bone breadth, girth).
    • Measurements are taken on the Right side of the body to avoid left-right asymmetry.
    • Skinfolds: Triceps, Subscapular, Supraspinale, Medial Calf
    • Bone Breadth: Humerus, Femur
    • Girth: Arm, Calf

    Plotting Somatotypes

    • Plotting methods: Determining body type from measurements.

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    Description

    Test your understanding of the biomechanics of levers, muscle movements, and bone remodeling. This quiz covers first, second, and third class levers, as well as the effects of stress on bone structure. Dive into the fundamental principles that govern human movement and skeletal adaptation.

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