Recording-2025-02-18T16:48:22

Joint Classification: Structural and Functional

Structural Joint Classes

• Fibrous Joints

  • No cartilage.

  • Held together by fibrous connective tissue.

  • Examples: Sutures, Syndesmoses, Gomphoses.

• Cartilaginous Joints

  • Composed of cartilage (hyaline or fibrocartilage).

  • Slight movement possible.

  • Examples: Synchondrosis (growth plates), Symphysis (spine discs, pubic symphysis).

• Synovial Joints

  • Contain a joint capsule, cartilage, and ligaments.

  • Permit free movement.

  • Examples: Elbow, knee, shoulder, hip.

Functional Joint Classes

• Synarthrotic Joints (Synarthrosis)

  • Little to no movement.

  • Example: Skull sutures.

• Amphiarthrotic Joints (Amphiarthrosis)

  • Slight movement.

  • Example: Disc of the spine and pubic symphysis.

• Diarthrotic Joints (Diarthrosis)

  • Freely movable.

  • Examples: All major limb joints (shoulder, hip, elbow, knee).

Key Terminology and Details

Synarthrotic Joints

• Generally considered immovable.

• Example: Sutures in the adult skull.

• Movement possibilities are negligible and not clinically significant.

Amphiarthrotic Joints

• Allow slight movement.

• Generally provide stability and some flexibility.

• Example: Intervertebral discs and pubic symphysis.

Diarthrotic Joints

• Designed for extensive movement.

• Key joints studied include:

  • Shoulder

  • Hip

  • Knee

  • Elbow

  • Wrist

  • Fingers

Special Features of Synovial Joints

• Articular Capsule

  • Contains synovial fluid that nourishes and lubricates the joint.

• Hyaline Cartilage

  • Covers the surfaces of bones at the joint, acting as a cushion and reducing friction.

• Fibrocartilage Features

  • Meniscus: Found in the knee, provides additional cushioning and stability.

  • Articular Disc: Present in the temporomandibular joint (TMJ), enhances fit and movement of the joint.

  • Labrum: Provides stability in the shoulder and hip joints.

• Bursa

  • Small fluid-filled sacs that reduce friction between tissues.

  • Located in high-friction areas like the shoulder, knee, elbow.

• Tendon Sheath

  • Tubular structure surrounding tendons, reducing friction during movement.

  • Important in areas with repetitive movement such as wrists and ankles.

Types of Synovial Joints

Major Subclasses

1. Ball-and-Socket Joints

   • Example: Shoulder and hip.

   • Allows multidirectional movement.

2. Hinge Joints

   • Example: Elbow and knee.

   • Allow for flexion and extension only.

3. Pivot Joints

   • Example: Radius and ulna, top of the neck.

   • Allow for rotational movement.

4. Plane (Gliding) Joints

   • Example: Wrist and ankle bones.

   • Allow for sliding movements in multiple directions.

Additional Classes

5. Condyloid Joints

   • Example: Knuckles (metacarpophalangeal joints).

   • Allow movement but not rotation.

6. Saddle Joints

   • Example: Base of the thumb.

   • Allow movement in two planes.

Joint Pathologies

Osteoarthritis

• Degenerative joint disease characterized by the loss of hyaline cartilage.

• Symptoms include pain, stiffness, reduced mobility.

Rheumatoid Arthritis

• Autoimmune disorder where the immune system attacks joint tissues.

• Symptoms are inflammatory, including swelling, pain, and potential joint deformation.