Arthrology: Joint Types and Function

• Arthrology is the study of joints, which are vital for movement and stability.
• The range of motion at a joint is determined by bony structure, ligaments/connective tissues, and muscle tightness.

Functional Joint Classification

• Synarthrosis: Immovable joints such as bony fusions, cartilaginous, and fibrous joints.
• Amphiarthrosis: Slightly movable joints like fibrous (syndesmosis) and cartilaginous (symphysis) joints.
• Diarthrosis: Freely movable joints or Synovial Joints, are the most common type (e.g., knee, elbow).

Structural Joint Classification

• Bony Fusion (Synostosis): Direct bone connections, exemplified by skull sutures in adults.
• Fibrous Joints: Held together by connective tissue (e.g., sutures, syndesmoses, gomphoses).
• Cartilaginous Joints: Held together by cartilage e.g., synchondrosis, symphysis.
• Synovial Joints: Freely movable, featuring a joint capsule, articular cartilage, joint cavity with synovial fluid, synovial membrane, and ligaments (extrinsic, intrinsic, capsular), fibrocartilage pads & fat pads.

Types of Synovial Joints

• Gliding Joint: e.g., intercarpal joints
• Hinge Joint: e.g., elbow, knee
• Pivot Joint: e.g., atlas-axis joint in the neck
• Ellipsoidal (Condyloid) Joint: e.g., wrist
• Saddle Joint: e.g., thumb joint
• Ball and Socket Joint: e.g., shoulder, hip

Common Joint Disorders

• Bursitis: Inflammation of bursae.
• Arthritis: Inflammation and degeneration of joints.
  • Osteoarthritis: Wear and tear of hyaline cartilage.
  • Rheumatoid Arthritis: Autoimmune disorder attacking synovial joints.
• Synovitis: Inflammation of synovial membrane.
• Joint Dislocation (Luxation): Complete misalignment of joint.
• Subluxation: Partial joint dislocation.
• Sprains and Strains: Ligament or tendon injuries.

Knee Joint (Genu) Anatomy

• The knee joint is the body's largest synovial joint.
• Bones include the Femur, Tibia, and Patella

Knee Articulations

• Tibiofemoral Joint: A double condyloid synovial joint between the femur and tibia.
• Patellofemoral Joint: A gliding synovial joint between the patella and femur.

Knee Movements

• Sagittal Plane: Flexion, Extension, Hyperextension
• Transverse Plane: Medial and Lateral Rotation
• Frontal Plane: Abduction (Valgus), Adduction (Varus)

External Knee Ligaments

• Medial Collateral Ligament (MCL): Resists valgus forces.
• Lateral Collateral Ligament (LCL): Resists varus forces.
• Patellar Tendon: Connects quadriceps to tibia.
• Patellar Retinaculum: Provides medial and lateral knee support.

Internal Knee Ligaments

• Anterior Cruciate Ligament (ACL): Prevents anterior displacement of tibia and posterior displacement of femur and is tight in extension.
• Posterior Cruciate Ligament (PCL): Prevents posterior displacement of tibia and anterior displacement of femur and is tight in flexion.

Other Knee Structures

• Menisci (Medial & Lateral): Stabilize femur on tibia and spread out forces within the joint; outer 1/3 is vascularized.
• Plica: Permanent fold of synovial membrane.

Abnormal Knee Alignments

• Genu Recurvatum: Excessive hyperextension in the sagittal plane.

Frontal Plane Issues

• Genu Valgum (Knock-Knees): Medial tibiofemoral angle >195°.
• Genu Varum (Bowlegs): Medial tibiofemoral angle <180°.

Explore arthrology, the study of joints, crucial for movement and stability. Learn about functional classifications like synarthrosis, amphiarthrosis, and diarthrosis. Understand structural classifications including bony fusion, fibrous, cartilaginous, and synovial joints.