biomechanics 3

Page 1: Introduction to the Musculo-skeletal System

  • Contact Information

    • Dr Elena Seminati

    • Email: e.seminati@bath.ac.uk

    • Course Code: HL10522

  • Lecture Focus

    • Functional Anatomy and Biomechanics

    • Overview of Bones, Joints & Muscles

  • Anatomical Reference Position

    • Starting position for body movements:

      • Upright standing position

      • Facing forward

      • Legs together

      • Feet flat on the floor

      • Hands at the side

      • Palms facing forward

Page 2: Anatomical Reference Planes

  • Anatomical Reference Planes

    • Frontal (Coronal)

    • Transverse (Horizontal)

    • Sagittal (Median)

  • Cardinal Planes

    • Imaginary planes dividing the body in half by mass

    • Intersect at the body's center of mass

  • Fundamental Movements

    • Sagittal Plane Movement (Mediolateral Axis)

      • Flexion: Diminishing angle at the joint

      • Extension: Increasing angle at the joint

Page 3: Fundamental Movements Continued

  • Frontal Plane Movement (Anteroposterior Axis)

    • Abduction: Movement away from the midline

    • Adduction: Movement towards the midline

  • Transverse Plane Movement (Longitudinal Axis)

    • Rotation: Involves turning left or right (e.g., neck, trunk)

Page 4: Functions and Types of Bones and Joints

  • Today's Overview

    • Understanding bones' roles and organization

    • Processes of normal growth and maturation of bones

    • Categorizing joints by structure and movement capabilities

  • Functions of the Skeleton

    • Movement: Muscle attachment and leverage

    • Support: Provides shape

    • Protection: Safeguarding vital organs

    • Physiological Functions:

      • Calcium regulation

      • Endocrine regulation

      • Blood cell production (in bone marrow)

Page 5: Movements and Levers

  • Lever: Rigid object rotating about an axis due to applied force

    • Components:

      • Resistance (weight)

      • Effort (applied force)

      • Pivot (fulcrum)

  • Human Body as Lever Systems

    • Joints act as pivots, muscles as effort, and body parts as resistance

Page 6: Types of Lever Systems

  • Three Classes of Levers

    • 1st Class Levers

    • 2nd Class Levers

    • 3rd Class Levers (most common in human body)

Page 7: Tissues of the Musculo-skeletal (MSK) System

  • Types of Tissues

    • Skeletal Tissue: Bone, cartilage

    • Muscular Tissue

Page 8: Bone Composition & Structure

  • Bone Composition

    • Organic: 35% (primarily type 1 collagen for elasticity)

      • Cells: osteoblasts, lining cells, osteocytes, osteoclasts

    • Inorganic: 65% (mineral content - hydroxyapatite for rigidity)

Page 9: Bone Structure

  • Long Bones

    • Consist of:

      • Diaphysis (shaft)

      • Two Epiphyses

      • Metaphysis (location of growth plate)

  • Types of Bones

    • Cancellous/Spongy/Trabecular Bone

      • 20% of bone mass; reduces skeletal mass while maintaining strength

    • Compact/Cortical Bone

      • 80% of bone mass; provides mechanical function

Page 10: Bone Growth & Development

  • Types of Growth

    • Longitudinal Growth: At epiphyseal plates, stops around 18-20 years

    • Circumferential/Radial Growth: Increases diameter throughout life

  • Bone Response to Stress

    • Wolff’s Law: Bone adapts to load changes

Page 11: Bone Remodelling Responses

  • Bone Remodelling: Interaction of osteocytes, osteoblasts, and osteoclasts in load response

    • Hypertrophy: Increase in bone mass with regular physical activity

    • Example: Tennis players showing muscular and bone hypertrophy in playing arm

Page 12: Bone Remodelling Responses Continued

  • Atrophy: Decrease in bone mass from osteoclast predominance

    • Seen in bedridden patients, sedentary elderly, and astronauts

Page 13: Skeletal System

  • Total Bones: 74 (excluding sesamoid)

  • Commonly referenced bones: 126

Page 14: Classification of Bones by Shape

  • Flat Bones: Thin and curved, serve as attachment points for muscles and protect organs

  • Short Bones: Cube-shaped, equal in dimensions, provide limited movement

Page 15: Continuing Bone Classifications

  • Long Bones: Cylinder-shaped; longer than wide, functions as levers

  • Irregular Bones: Complex shape; protect internal organs from compressive forces

  • Sesamoid Bones: Embedded within tendons to alleviate stress

Page 16: Joint Function

  • Function of Joints: Facilitate movement between bones and transmit force

  • Articular Surface: Contact point between two skeletal bones

Page 17: Types of Joints - Synarthroses

  • Synarthroses: Non-moving joints (e.g., skull sutures)

    • Functions: Shock absorption and force attenuation

Page 18: Types of Joints - Amphiarthrosis and Diarthroses

  • Amphiarthrosis: Slightly movable joints, permit limited motion

  • Diarthroses: Free-moving joints (synovial); categorized into various types

    • Gliding/Plane joints: Non-axial movements

Page 19: Types of Diarthroses

  • Hinge Joints: Allow uni-axial hinge-like movements

  • Pivot Joints: Allow uni-axial rotation around an axis

Page 20: More Diarthroses

  • Condyloid Joints: Bi-axial movement around two axes

  • Saddle Joints: Tri-axial movement and greater range of motion

Page 21: Ball and Socket Joints

  • Ball and Socket: Allow rotation around three axes

  • Joint Architecture:

    • Articular Cartilage: Reduces stress, friction, and wear

Page 22: Joint Architecture Continued

  • Articular Capsule: Surrounds every synovial joint

    • Synovial Membrane: Secretes synovial fluid

  • Joint Stability: Resists abnormal displacement; provided by bone shape, ligament arrangement, and connective tissues

Page 23: Lecture Summary

  • Covered Topics:

    • Role of the skeleton

    • Functions and types of bones

    • Functions and types of joints

  • Suggested Activities:

    • Read Chapter 2 of the ‘Biomechanical Basis of Human Movement’: Skeletal considerations for movement