letcure 19

Human Anatomy and Physiology I

Lecture 19: Synovial Joints

Instructor: Dr. Shaun D. Cain
Course: Biol 231 Fall 2025
Institution: Eastern Oregon University

Types of Synovial Joints

  • Joint Motion Categories:
    • Ball and Socket Joint
    • Example: Shoulder
    • Saddle Joint
    • Example: Thumb
    • Hinge Joint
    • Example: Elbow
    • Pivot Joint
    • Ellipsoid/Condyloid Joint
    • Example: Wrist
    • Plane/Gliding Joint
    • Example: Feet

Movements at Synovial Joints

  • Gliding Movements:
    • Description: Sliding motion between articulating surfaces; classified as nonaxial.

Specific Types of Angular Motion:

  • Flexion:
    • Definition: Decreases the angle between bones by bringing them closer together.
  • Extension:
    • Definition: Increases the angle between bones (the opposite of flexion), causing the bones to move away from one another.
  • Hyperextension:
    • Definition: Extension beyond the anatomical position of the joint.

Abduction and Adduction:

  • Abduction:
    • Definition: Movement of a body part away from the midline of the body or another reference point.
  • Adduction:
    • Definition: Movement of a body part toward the midline of the body or another reference point; the opposite of abduction.

Circumduction:

  • Circumduction:
    • Definition: Unpaired angular movement where the freely movable distal bone moves on a fixed proximal bone in a cone-shaped motion; it is a combination of flexion-extension and abduction-adduction.

Rotation:

  • Rotation:
    • Definition: Nonangular motion where one bone rotates around an imaginary line that runs down its middle longitudinal axis.

Special Movements

  • Types of Movements Not Defined by Previous Categories:
    • Opposition and Reposition:
    • Opposition:
      • Definition: Movement at the first carpometacarpal joint allowing the thumb to move across the palmar surface of the hand.
    • Reposition:
      • Definition: The opposite movement that returns the thumb to its anatomical position.
    • Depression and Elevation:
    • Depression:
      • Definition: Movement of a body part in an inferior direction.
    • Elevation:
      • Definition: Movement of a body part in a superior direction.
    • Protraction and Retraction:
    • Protraction:
      • Definition: Movement of a body part in an anterior direction.
    • Retraction:
      • Definition: Movement of a body part in a posterior direction.
    • Inversion and Eversion:
    • Inversion:
      • Definition: Rotational motion where the plantar surface of the foot rotates medially toward the midline of the body.
    • Eversion:
      • Definition: Rotation of the foot laterally away from the midline.
    • Dorsiflexion and Plantarflexion:
    • Dorsiflexion:
      • Definition: Decreases the angle between the foot and leg.
    • Plantarflexion:
      • Definition: Increases the angle between the foot and leg.
    • Supination and Pronation:
    • Definition: Rotational movements of the wrist and ankle regions.

Study Boost: Keeping Supination and Pronation Straight

  • Supination vs. Pronation:
    • Analogy: Hold a cup of soup; your hand is in a supinated position. When you pour it out, your hand pronates.
  • Abduction vs. Adduction:
    • Abduction: To abduct (take away) a part from the body.
    • Adduction: To add a part back to the body.

Specific Hinge Joints

  • Knee:
    • Patellar Ligament:
    • Definition: The distal continuation of the quadriceps tendon; connects the distal patella to the anterior tibia.
    • Tibiofemoral Joint:
    • Definition: Articulation between the femoral and tibial condyles.
    • Patellofemoral Joint:
    • Definition: Articulation between the posterior surface of the patella and the anterior surface of the femur.
    • Medial and Lateral Meniscus:
    • Definition: C-shaped fibrocartilaginous pads located between the femoral and tibial condyles; they serve as shock absorbers and enhance joint stability.
    • Tibial Collateral Ligament (Medial Collateral Ligament):
    • Definition: Connects the femur, medial meniscus, and tibia together; provides medial joint stabilization and prevents the tibia from shifting too far laterally on the femur.