ZL

Study Notes on Joints

Chapter 9: Joints

Overview

  • Lecture slides prepared by Curtis DeFriez, Weber State University

  • Copyright © John Wiley & Sons, Inc. All rights reserved.

Structures, Functions, and Types of Joints

  • Joints can be classified structurally and functionally, with resources available at education-portal.com pertaining to joint structure and function.

    • Structural classification encompasses anatomical criteria, such as the presence or absence of a space between articulating bones and the type of connective tissue (C.T.) binding the bones together.

    • Functional classification addresses the degree of movement joints permit.

Joint Classification

  • Structural and Functional Classifications:

    • Joints are classified based on two criteria: structural (anatomical) and functional (movement).

Structural Classification Subcategories

  1. Fibrous Joints

    • Definition: Joints held together by dense collagen fibers.

    • Characteristics: Lack cartilage and a synovial cavity; bones are closely bound by dense irregular connective tissue.

    • Examples:

      • Suture joints in the skull

      • Teeth joints

  2. Cartilaginous Joints

    • Definition: These joints consist of cartilage bridging the two bones.

    • Characteristics: No synovial cavity; provide little to no movement.

    • Examples:

      • Pubic symphysis

      • Intervertebral disks of the spine

  3. Synovial Joints

    • Definition: More complex joints where ligaments connect the bones, forming a synovial cavity and allowing free movement.

    • Characteristics: Consist of a two-layered capsule:

      • An outer fibrous capsule

      • An inner synovial membrane

Functional Classification Subcategories

  1. Synarthrosis

    • Definition: An immovable joint.

    • Examples: Fibrous joints of the skull.

  2. Amphiarthrosis

    • Definition: A slightly movable joint.

    • Examples: Cartilaginous pubic symphysis.

  3. Diarthrosis

    • Definition: A freely movable joint.

    • Examples: Ball and socket synovial joints of the shoulder and hip.

Components of Synovial Joints

  • Synovial Membrane

    • Function: Secretes synovial fluid that:

    • Reduces friction by lubricating the joint.

    • Absorbs shocks during movement.

    • Supplies oxygen and nutrients to the cartilage while removing carbon dioxide and metabolic wastes.

  • Major Joints

    • Found in the arms, hips, and legs.

Summary of Joint Types

  • Immovable Joints: Synarthroses (like skull joints)

  • Slightly Movable Joints: Amphiarthroses (like the pubic symphysis)

  • Freely Movable Joints: Diarthroses (like shoulder and hip ball and socket joints)

Ethical and Practical Implications

  • Understanding joint types and functions provides insight into anatomy, physiology, and potential treatment for joint-related conditions.