Second half Notes on Joints and Motion

Joints and Motion

Overview of Joints

  • Joint Types and Functionality

    • Focus on synovial joints, characterized by a synovial cavity, articular cartilage, articular capsule, and synovial fluid.

    • Explore different joint types such as hinge, ball-and-socket, saddle, etc.

Specific Joints Discussed

Shoulder Joint

  • Anatomical Features

    • Comprised of the head of the humerus and the glenoid cavity of the scapula.

    • Joint is very mobile due to a shallow socket.

  • Biceps Tendon

    • Tendon goes over the top of the humerus to the scapula, attaches to the glenoid cavity.

    • It is surrounded by a tendon sheath containing synovial fluid to reduce friction.

  • Bursa

    • Small pillows of synovial fluid that help reduce friction between the bones and ligaments.

    • Examples include subacromial and subscapular bursae.

    • Condition of inflammation is termed bursitis, frequently experienced by athletes (e.g., after strenuous activities).

  • Glenoid Labrum

    • A fibrocartilaginous lip that deepens the glenoid cavity to provide stability against dislocations.

  • Shoulder Dislocations

    • Dislocation often occurs inferiorly and anteriorly due to muscle imbalance (e.g., pectoralis major).

    • High risk for recurrence after an initial dislocation.

  • Shoulder Separations

    • Involve the acromioclavicular joint, usually more difficult to achieve than a dislocation.

Elbow Joint

  • Anatomical Features

    • Strong radial and ulnar collateral ligaments supporting the joint.

  • Injuries

    • Commonly associated with forceful extensions such as in pitching.

    • Ulnar collateral ligament tears are prevalent in pitchers and can require Tommy John surgery, named after pitcher Tommy John who popularized the recovery procedure.

Hip Joint

  • Anatomy and Structure

    • Deep socket provided by the acetabulum and reinforced by the acetabular labrum.

    • Ligamentum teres connects the head of the femur to the hip bone and may carry blood vessels.

  • Injury Potential

    • Hip fractures often occur in the neck region; blood vessel presence can affect healing (necrosis if absent).

    • Dislocations are less common, but can occur with specific movements, especially in car accidents.

Knee Joint

  • Components

    • Complex structure involving femur, tibia, patella, articular cartilage, multiple bursa (e.g., suprapatellar, prepatellar).

  • Cruciate Ligaments

    • Anterior cruciate ligament (ACL) runs from anterior tibia to posterior femur; essential for stabilization during motion.

    • Posterior cruciate ligament (PCL) runs from posterior tibia to anterior femur.

  • Menisci

    • Medial and lateral meniscus help deepen the joint and absorb shock.

  • Injuries

    • ACL tears can occur with sharp movements and are often associated with the “terrible triad” injury (ACL, MCL, medial meniscus).

Ankle Joint

  • Injuries

    • Most frequent injuries involve inversion or eversion causing sprains.

    • High ankle sprains involve the syndesmosis between tibia and fibula and can lead to more severe complications (e.g., fibula fractures).

    • Named for the arrangement of ligaments affected during injury.

Summary of Concepts

  • Common Conditions

    • Bursitis and various ligament injuries are common in athletes due to overuse and trauma.

  • Importance of Lab Manuals

    • Refer to specific pages to correlate with lab observations and practical exams.

Conclusion of the Module

  • This concludes the first module. Focus on reviewing lab materials to correlate anatomical structures and their functions learned in lecture.