Musculoskeletal System Overview

• Presenter: Chris Bellis, Senior Lecturer in Physiotherapy, Wrexham University

Learning Outcomes

• Identify the anatomical structures and components of the musculoskeletal system.

• Describe the physiological functions and mechanisms of the musculoskeletal system.

• Explain pathophysiological changes due to common illnesses, diseases, injuries, and well-being conditions.

What is the Musculoskeletal System?

• Comprises muscles, connective tissue, and bones.

• Provides stability and movement.

• Initiation of movement and coordination is managed by the nervous system.

Skeletal System

• Cartilage Types (only two in the musculoskeletal system):

  • Hyaline Cartilage:

    • Found in articular joints, providing shock absorption and smooth surfaces.

    • Connects ribs to sternum, also present in trachea and nose.

  • White Fibrocartilage:

    • High tensile strength; found in intervertebral discs, symphysis pubis, labrum, and TMJ.

Bone Structure

• Composition:

  • Fibrous connective tissues and mineral salts.

  • Protects and supports the body while being lightweight.

• Types of bone:

  • Compact Bone and Cancellous (Spongy) Bone.

• Function: Formation of red and white blood cells occurs in red bone marrow.

Bone Classification

• Long Bones: Contains a shaft (diaphysis) and two epiphyses.

• Short Bones: Example - carpal bones.

• Flat Bones: Example - sternum.

• Irregular Bones: Example - vertebrae.

• Sesamoid Bones: Example - patella, sesamoid of thumb.

Articular Surface Components

• Articular Cartilage

• Epiphyseal Line and Epiphyseal Plate

• Spongy Bone

• Compact Bone

• Medullary Cavity: Contains yellow marrow.

• Periosteum: Outer layer of bone.

Anatomical Identification on Skeleton

• Cranial Bones

• Facial Bones

• Mandible

• Clavicle

• Sternum

• Humerus

• Vertebrae

• Coxal (hip) Bone

• Radius/Ulna

• Carpals/Metacarpals/Phalanges

• Femur/Patella/Tibia/Fibula/Tarsals

Muscle Structure and Function

• Skeletal Muscle Components:

  • Tendon: Attach muscle to bone, composed of collagenous fibrous tissue.

  • Fascia: Connective tissue layers.

  • Muscle Fibers:

    • Thick Filaments: Composed of myosin (golf club shape).

    • Thin Filaments: Composed of actin, tropomyosin, and troponin.

Muscle Contraction Mechanism

• Sliding Filament Theory:

  • Calcium ions bind to troponin, moving tropomyosin and exposing actin’s active sites.

  • Myosin cross bridges bind to actin and utilize ATP to pull the thin filaments towards the center of the sarcomere, resulting in muscle fiber contraction.

Types of Muscle Action

• Isotonic Contraction:

  • Concentric: Muscle shortens to produce movement.

  • Eccentric: Muscle lengthens to produce movement.

• Isometric Contraction: Muscle length remains unchanged.

• Roles:

  • Agonist: Prime mover for movement.

  • Antagonist: Relaxes while agonists contract.

  • Synergists: Assist prime movers for effective movement.

Movements Terminology

• Flexion and Extension: Joint angle changes.

• Lateral/Medial Rotation: Rotational movements of limbs.

• Dorsiflexion/Plantarflexion: Foot movements.

• Inversion/Eversion: Foot positioning.

• Abduction/Adduction: Movements away from or toward the body.

• Supination/Pronation: Rotational movement of the forearm.

Common Pathologies - Fractures

• Classification:

  • Closed/Open (Compound): Types of fractures.

  • Transverse/Oblique/Spiral: Different fracture patterns.

  • Displaced and Non-Union: Healing issues.

Common Pathologies - Osteoarthritis

• Clinical Diagnosis:

  • Age 45+, activity-related joint pain, with no morning stiffness or stiffness lasting less than 30 minutes.

• Prevalence:

  • 70% over age 65 have radiographic evidence.

• Pathophysiology: Loss of articular cartilage, osteophyte formation, and synovial changes.

Inflammation Signs

• Rubor: Redness due to increased blood flow.

• Calor: Heat from metabolic reactions.

• Tumor: Swelling from fluid accumulation.

• Dolor: Pain due to nociceptors reacting to edema and chemicals.

Pain Definition Revision by IASP**

• Current Definition: An unpleasant sensory and emotional experience associated with potential tissue damage.

• Revised Thought: Pain is personal, influenced by biological, psychological, and social factors.

• Importance of acknowledgement of non-verbal expressions of pain.

References

• Patton, K. (2019). Anatomy and Physiology, Adapted International Edition, UK: Elsevier.

• Soames, R., & Palastanga, N. (2019). Anatomy and Human Movement, 7th Ed., UK: Elsevier.