Joints-Midterm PDF

# Musculoskeletal System: Joints ## KKU_Biomech_M1_L2 **Dr/Shimaa Essa** Lecturer of physical therapy, faculty of community, King Khalid university ## Lesson (2): Joints ### Objectives Upon successful completion of this lesson you would be able to: - Define joint. - Identify functions of Joi...

# Musculoskeletal System: Joints ## KKU_Biomech_M1_L2 **Dr/Shimaa Essa** Lecturer of physical therapy, faculty of community, King Khalid university ## Lesson (2): Joints ### Objectives Upon successful completion of this lesson you would be able to: - Define joint. - Identify functions of Joints. - Distinguish between different classifications of joints. - Identify degrees of freedom for different joints in the human body. ## Introduction - Joint is the meeting of two bones or more in the skeletal system. - Or, it is the connection (or articulation) in the skeleton between any of its rigid component parts, whether bones or cartilages. ## Arthrology - **Arthr:** means joint or articulation. - **Ology:** means the science that deals with. - Arthrology is the branch of anatomy concerned with the joints. Therefore, arthrology is the science of studying joints. ## What are Joints? A joint, or articulation, is the place where two bones come together. ## How are Joints Classified? ### Functional Classification - Focuses on the amount of movement allowed. - Immovable, slightly movable, freely movable. ### Structural Classification - Focuses on the material that binds the joint together. - **Fibrous joints:** Immovable - **Cartilaginous joints:** slightly movable - **Synovial joints:** freely movable ## Classifications of Joints ### Structural Classifications #### Fibrous Joints - **Synarthrosis** and **synostoses** are immovable. - They connect bones, and there is no movement. - Examples are the skull and pelvis. #### Cartilaginous Joints - **Amphiarthrosis** is slightly movable. - Bones are attached by cartilage, and there is a little movement. - Examples include the spine or rib's cartilage. #### Synovial Joints - **Diarthrosis** is freely movable, with much more movement than cartilaginous joints. - Cavities between bones are filled with synovial fluid which lubricates and protects the bones. ### What are Fibrous Joints? - Collagen fibers join bones. - They lack a joint cavity, and are composed of fibrous connective tissue. - They are usually synarthrotic. #### Types - **Sutures:** Found in the skull and become bone in middle age. - **Gomphoses:** The periodontal ligament of teeth holds the tooth in place. - **Syndesmoses:** Short ligaments bind two bones. - Example: Radius and ulna, tibia and fibula. ### What are Bony Joints? - **Synostoses** are two bones that were once separate but are now fused. - Examples include the frontal bone and the epiphyseal line. ### What are Cartilaginous Joints? - Cartilage binds two bones. - There is no joint cavity. - They are usually amphiarthrotic. #### Types - **Synchrondroses:** Hyaline cartilage joins. - Example: Epiphyseal plate, costal cartilage (to sternum). - **Symphyses:** Fibrocartilage joins. - Example: Pubic symphysis, intervertebral joints. ### What are Synovial Joints? - They have a joint cavity between two bones. - Synovial fluid fills the space. - They are always diarthrotic. - Examples include: shoulder, knee, elbow, hip. ### What are the Components of a Synovial Joint? 1. **Joint (articular) cavity:** Contains slippery fluid. - The articular capsule and cartilage bind the cavity. 2. **Two capsule layers:** - **Outer fibrous CT capsule:** Continuous with the periosteum. - **Inner synovial membrane:** Connective tissue that secretes fluid. 3. **Meniscus:** A pad of cartilage that is continuous with the synovial membrane, acting as a shock absorber. 4. **Tendon:** Dense regular connective tissue that attaches muscle to bone. 5. **Ligament:** Dense regular connective tissue that attaches bone to bone. ### What Types of Synovial Joints are There? - Joints are classified as *mono*, *bi*, and *multiaxial*. - **Hinge Joint:** A uniaxial joint (flexion and extension) - Examples: Elbow, knee, finger/toe - **Ball-and-Socket Joint:** The most moveable joint. - Multiaxial: - Examples: Shoulder and hip joints. - **Pivot Joint:** Monoaxial (rotation) - Examples: Atlas-axis, radioulnar - **Saddle Joint:** Biaxial, with only one joint at the base of the thumb (1st carpometacarpal joint). - **Condyloid Joint:** Round (modified ball and socket), biaxial. - Examples: Metacarpophalangeal joints (base of fingers). - **Ellipsoid Joint:** Ovoid shaped joint that allows flexion, extension, abduction, and adduction It is biaxial. - Examples: Radiocarpal articulation (wrist joint). - **Compound Joint:** Composed of two types of joints, multiaxial. - Examples: Temporomandibular joint (hing + gliding). The temporomandibular joint allows flexion, extension, protrusion, retrusion, and sideway movements. ### Types of Synovial Joints Based on Shape | | | | | | --- | --- | --- | --- | | **(a) Plane Joint** | **(b) Hinge Joint** | **(c) Pivot Joint** | **(d) Condyloid Joint** | | **(e) Saddle Joint** | **(f) Ball-and-Socket Joint** | | | - **Nonaxial:** No movement - **Uniaxial:** Movement in one plane - **Biaxial:** Movement in two planes - **Multiaxial:** Movement in three planes ## Summary of Joint Classes | Structural Class | Characteristics | Types | Mobility | | ---------------- | ---------------------------------------------- | ----------------------------------------------------- | --------------------------------------------------- | | FIBROUS | Bones united by collagen fibers | 1. Suture, 2. Syndesmosis, 3. Gomphosis | 1. Immobile (synarthrosis), 2. Slightly movable (amphiarthrosis) | | CARTILAGINOUS | Bone ends united by cartilage | 1. Synchondrosis (hyaline), 2. Symphysis (fibrocartilage) | 1. Immobile, 2. Slightly movable | | SYNOVIAL | Bone ends covered with articular cartilage and enclosed within a capsule lined with a synovial membrane | 1. Gliding/Plane, 2. Hinge, 3. Pivot, 4. Condyloid, 5. Saddle, 6. Ball and socket, 7. Ellipsoid, 8. Compound | Freely movable (diarthrosis) which depends on joint design | ## Thank You