Articulations and Muscular System Overview

Articulations and Muscular System Overview

Exam 2 Focus

  • Key chapters for study:
    • Chapter 8.1: Overview of Joints
    • Chapter 8.2: Fibrous and Cartilage Joints
    • Chapter 8.3: Structure of Synovial Joints
    • Chapter 8.4: Function of Synovial Joints
    • Chapter 8.5: Types of Synovial Joints
    • Chapter 9.1: Overview of Skeletal Muscles

Chapter 8.1: Learning Outcomes

  • Describe the basic functions of joints.
  • Describe the classification of joints both structurally and functionally.
Joint Functions
  • Articulate: To connect two bones.
  • Functions of joints include:
    1. Movement: Allowing mobility.
    2. Stability: Providing support and integrity to skeletal framework.
    3. Lengthening of long bones: Essential for growth and development.
Joint Classes
  • Classification of joints based on:
    1. Functional aspects: Primarily movement-related.
    2. Structural aspects: Based on anatomical features.
Functional Classification of Joints

  • Synarthrosis:

    • Definition: No movement, maximally stable.
    • Etymology: "syn" means together.

  • Amphiarthrosis:

    • Definition: Partial movement, stable.
    • Etymology: "Amphi" means both.

  • Diarthrosis:

    • Definition: Free movement, stable.
    • Etymology: "Di" means through.
Structural Classification of Joints

  • Fibrous Joints:

    • Definition: Comprised of short collagen fibers, no synovial cavity, can be synarthrosis or amphiarthrosis.

  • Cartilaginous Joints:

    • Definition: Comprised of cartilage, no synovial cavity, can be synarthrosis or amphiarthrosis.

  • Synovial Joints:

    • Definition: Have a cavity filled with fluid, classified as diarthrosis.
Review Question (Joint Stability)
  • Concept: The more movement a joint has, the less stable it is.

Chapter 8.2 Learning Outcomes

  • Goals:
    • Compare and contrast three subclasses of fibrous joints.
    • Provide examples of fibrous joints and describe their function.
    • Compare and contrast two subclasses of cartilaginous joints with examples and functions.
Fibrous Joints Characteristics
  • Composed of short collagen fibers and no space, can be synarthrosis or amphiarthrosis.
  • Types of fibrous joints include:
    1. Sutures (e.g., connections in the skull):
    • Function: Stable synarthroses, think "zipper" analogy.
    • Example: Coronal suture between parietal and frontal bones.
    1. Gomphoses (tooth and maxilla joint):
    • Function: Stable synarthroses, connected via periodontal ligament.
    • Components: Alveolar socket and tooth.
    1. Syndesmoses:
    • Function: Amphiarthroses, allows slight movement.
    • Examples: Connections between radius and ulna; tibia and fibula.
Cartilaginous Joints Features
  • Joint comprised of cartilage, no space.
  • Types of cartilaginous joints include:
    1. Synchondroses (Synarthroses):
      • Connection: Bones connected by hyaline cartilage.
      • Examples: Epiphyseal plates and costochondral joints.
    2. Symphyses (Amphiarthroses):
      • Composition: Tough fibrocartilage pad.
      • Examples: Intervertebral discs and pubic symphysis.
Review Question (Joint Movement)
  • Concept: Symphyses allow for more movement than sutures because symphyses are amphiarthrosis which enables some degree of movement, whereas sutures are synarthrosis, permitting no movement.

Chapter 8.3 Learning Outcomes

  • Goals:
    • Identify structural components of synovial joints.
    • Compare and contrast synovial joints with fibrous and cartilaginous joints.
Overview of Synovial Joints
  • Most body joints are synovial (diarthroses), allowing movement but are less stable than other joint types.
Structural Components of Synovial Joints

  1. Articular Cartilage:

    • Definition: Hyaline cartilage covering exposed articulating surfaces.
    • Functions: Reduces friction and provides shock absorption; avascular.

  2. Articular Capsule or Joint Capsule:

    • Definition: Two layers of connective tissue:
      • Outer layer isolates moving parts.
      • Inner layer secretes synovial fluid for nutrient transport (waste, nutrients, oxygen).

  3. Synovial Fluid:

    • Functions:
      • a) Lubrication: Decreases friction in joint.
      • b) Metabolic functions: Provides nutrients and aids in waste removal.
      • c) Shock absorption: Distributes force across the joint.
Stabilizing Structures in Synovial Joints

  1. Ligaments: Connect bone to bone with dense regular collagenous connective tissue, either

    • Intrinsic or extrinsic to the joint capsule.

  2. Tendons: Attach muscles to bones and stabilize when muscles contract.

  3. Bursae: Synovial fluid-filled sacs reducing friction in high-force areas.

  4. Tendon Sheaths: Specialized types of bursae surrounding tendons.

Pathology: Arthritis
  • Joint inflammation characterized by:
    1. Osteoarthritis: Age-related, manageable through various treatments.
    2. Rheumatoid Arthritis: Autoimmune condition requiring medication management.
    3. Gout: Accumulation of uric acid around joints, medicated appropriately.

Chapter 8.4 Learning Outcomes

  • Objectives:
    • Define functional classes of synovial joints.
    • Describe and demonstrate various movements associated with synovial joints.
Functional Classification of Synovial Joints
  1. Uniaxial: Movement occurring in one axis (e.g., elbow joint).
  2. Biaxial: Movement in two axes (e.g., metacarpophalangeal joints).
  3. Multiaxial: Movement across three axes (e.g., shoulder joint).
Types of Synovial Joint Movements

  1. Glide:

    • Definition: Sliding motion between articulating surfaces.
    • Example: Intercarpal joints.

  2. Angular Movements: Occur between two bones:

    • Flexion: Decrease in the angle between bones.
    • Extension: Increase in angle; return to anatomical position.
    • Hyperextension: Extension beyond anatomical position.
    • Abduction: Movement away from median line.
    • Adduction: Movement toward median line.
    • Circumduction: Conical movement of a body part, involving flexion, extension, abduction, and adduction.

  3. Rotational Movements: Pivot around an axis:

    • Internal Rotation: Toward the midline.
    • External Rotation: Away from midline.

  4. Special Movements: Include diverse actions:

    • Opposition: Thumb across palm and reposition back.
    • Elevation: Movements superiorly; Depression: Movements inferiorly.
    • Protraction: Anterior movement; Retraction: Posterior movement.
    • Inversion: Sole of foot turns toward midline; Eversion: Sole turns away from midline.
    • Dorsiflexion: Toes point upwards; Plantarflexion: Toes point downwards.
    • Supination: Forearm and palm face anterior; Pronation: Forearm and palm face posterior.
Review Problem on Joint Mobility
  • Query: Based on functional classification, range of motion in synovial joints spans from multiaxial to uniaxial.

Chapter 8.5 Learning Outcomes

  • Goals:
    • Describe anatomical features of each structural type of synovial joint.
    • Predict the types of movements allowed by each synovial joint type.
Types of Synovial Joints

  1. Plane Joints:

    • Characteristics: Two bones side by side; nonaxial, allow gliding.
    • Example: Intercarpal joints.

  2. Hinge Joints:

    • Characteristics: Convex bone fits into concave depression; uniaxial.
    • Example: Elbow joint.

  3. Pivot Joints:

    • Characteristics: Rounded bone fits into a groove; uniaxial.
    • Example: Atlantoaxial joint (between atlas and axis vertebrae).

  4. Condylar Joints:

    • Characteristics: Convex bone into concave depression; biaxial with limited circumduction.
    • Example: Metacarpophalangeal joint.

  5. Saddle Joints:

    • Characteristics: Complementary concave/convex parts; biaxial with greater circumduction.
    • Example: Carpometacarpal joint of the thumb.

  6. Ball-and-Socket Joints:

    • Characteristics: One bone spherical, the other cup-shaped; multiaxial.
    • Example: Shoulder joint.
Review Problem: Comparing Joint Types
  • Similarity: Both hinge and condylar joints have a convex bone structure fitting into a concave depression.
  • Difference: Hinge joints are uniaxial while condylar joints are biaxial.

Chapter 9.1 Learning Outcomes

  • Objectives:
    • Understand the name of a muscle indicating its action or location.
    • Summarize major functions of skeletal muscles.
    • Define terms: agonist, antagonist, synergist, and fixator.
    • Differentiate among three classes of levers regarding structure, function, and examples.
Anatomy of Skeletal Muscle
  • Components of a skeletal muscle:
    • Fascia: Connective tissue surrounding muscles.
    • Fascicle: Bundles of muscle fibers.
    • Muscle Cell Fiber: The basic unit of muscle.
    • Epimysium: Surrounds entire muscle.
    • Perimysium: Encloses fascicles.
    • Endomysium: Surrounds individual muscle fibers.
Fascicle Patterns in Muscles
  1. Parallel: Evenly-spaced fascicles, equal width as tendon.
  2. Convergent: Broad on one end, tapering on the other.
  3. Pennate: Feather-like appearance:
    • Unipennate: One tendon.
    • Bipennate: Two tendons.
    • Multipennate: Multiple tendons.
  4. Circular: Sphincter-like muscles surrounding openings.
  5. Fusiform: Thicker in the middle, tapered at the ends.
Naming Muscles
  • Key aspects:
    • Major/Minor and Longus/Brief descriptors.
    • Structural connections, e.g., sternocleidomastoid connects chest and neck regions.
    • Functional roles: Flexor/Extender, Abductor/Adductor.
Muscle Function
  • Muscles contract to generate tension.
  • Work collaboratively in groups:
    • Agonists: Major force providers for action.
    • Antagonists: Oppose and slow down movement.
    • Synergists: Assist agonists to enhance performance and smooth motion.
    • Fixators: Stabilize joints to improve efficiency and reduce risk of injury.
Muscle Origin and Insertion
  • Origin (O): Fixed point of muscle attachment.
  • Insertion (I): Point moved during contraction.
  • Example: Biceps brachii originates from coracoid process and supraglenoid tubercle, with insertion at radial tuberosity.
Muscles as Levers
  • Key lever types in the body include:
    1. First-Class Lever: Fulcrum is middle (e.g., seesaw analogy).
    2. Second-Class Lever: Load is in the middle (e.g., wheelbarrow analogy).
    3. Third-Class Lever: Force is in the middle (e.g., tongs analogy).
Summary of Lever Types
  • First-Class Lever: Load - Fulcrum - Force.
  • Second-Class Lever: Fulcrum - Load - Force.
  • Third-Class Lever: Fulcrum - Force - Load.
Groupwork Exercise
  • Identify muscle types using anatomical knowledge and name explanations, emphasizing:
    1. Locations in the body.
    2. Breakdown of each name into components.
    3. Synthesize insights regarding muscles' functions and locations.
  • Example Muscle: Tensor fasciae latae is found on the anterolateral thigh region. The name breakdown:
    • Tensor: tighten; Fasciae: band; Latae: wide area specific.
    • Hence, it aids in tightening thigh muscles.