Introduction Chapter 08 Lecture Outline See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Joints (Articulations): Functional junctions between bones Bind parts of skeletal system together Make bone growth possible Permit parts of the skeleton to change shape during childbirth Enable body to move in response to skeletal muscle contractions Copyright McGraw-Hill Education. Permission required for reproduction or display. 1 2 8.1: Types of Joints Structural Classification of Joints: Fibrous Cartilaginous Synovial Functional Classification of Joints: Synarthrotic immovable Amphiarthrotic slightly movable Diarthrotic freely movable 3 Fibrous joints are held together with dense connective tissue containing many collagen fibers; found in bones in close contact There are 3 types of fibrous joints: Syndesmosis Suture Gomphosis Syndesmosis: Bones bound by a sheet of dense connective tissue (interosseous membrane) or a bundle of dense connective tissue (interosseous ) Amphiarthrotic (flexible, may twist) Lies between tibia and fibula Fibrous Joints 4 Suture: Between flat bones of skull Thin layer of connective tissue (sutural ) connects bones Synarthrotic (immovable) Gomphosis: Cone-shaped bony process in a socket in jawbone Tooth in jawbone by periodontal Synarthrotic (immovable) Fibrous Joints 5 Cartilaginous Joints Cartilaginous joints are connected by hyaline cartilage or fibrocartilage There are 2 types of cartilaginous joints: Synchondrosis Symphysis Synchondrosis: Bands of hyaline cartilage unite bones Some are temporary, such as epiphyseal plate (ossification converts this to a synostosis) Between manubrium and the first rib (costal cartilages, permanent, synarthrotic) 6 1
Cartilaginous Joints Symphysis: Pad of fibrocartilage between bones Articular surfaces covered by hyaline cartilage Amphiarthrotic (limited movement) Pubic symphysis Joint between bodies of adjacent vertebrae (intervertebral discs) Synovial Joints: Most joints are synovial joints All are diarthrotic joints Synovial Joints Structure of s synovial joint: Articular cartilage covers articular ends of bones Joint capsule, consists of 2 layers: - Outer fibrous layer, composed of s - Inner layer, synovial membrane, which secretes synovial fluid 7 8 General Structure of Synovial Joints Synovial joints are more complex than other types of joints, and contain the following parts: Articular cartilage Joint capsule Ligaments Synovial membrane Synovial cavity Synovial fluid Meniscus (-i) in some joints Bursa (-ae) in some joints General Structure of Synovial Joints Diagram of the knee joint, showing typical synovial joint structures, as well as less common structures, such as menisci and bursae 9 10 There are 6 types of synovial joints, classified by shape and movements they allow: Ball-and-Socket Joint: Also called spheroidal joint Round head in cup-shaped cavity Widest range of motion Multiaxial, plus rotation Hip, shoulder Condylar Joint: Also called ellipsoidal joint Oval condyle fits into elliptical cavity Back-and-forth, side-to-side movement Biaxial movement, no rotation Joints between metacarpals & phalanges 11 Plane Joint: Also called gliding joint Almost flat, or slightly curved Back-and-forth and twisting Nonaxial movement Wrist and ankle joints Hinge Joint: Convex surface fits into concave surface of other bone Uniaxial movement (in 1 plane) Elbow, joints between phalanges 12 2
Pivot Joint: Also called trochoid joint Cylindrical surface rotates within ring of other bone Uniaxial movement Rotation only Atlas (C1) and dens of axis (C2) Saddle Joint: Also called sellar joint Both bones have concave and convex surfaces Biaxial movement (in 2 planes) Carpal & metacarpal of thumb 8.2: Action of skeletal muscle produces movement at synovial joints Relatively fixed end of a skeletal muscle is called the origin More movable end of a skeletal muscle is called the insertion Movement at a joint occurs when a muscle contracts, and its fibers pull the insertion towards the origin 13 14 Abduction / adduction Flexion / extension / hyperextension Lateral flexion Dorsiflexion / plantar flexion Circumduction / rotation Medial rotation / lateral rotation Supination / pronation 15 16 Inversion / eversion Protraction / retraction Elevation / depression 8.3: Examples of Synovial Joints Examples of large, complex synovial (also freely movable) joints: Shoulder Elbow Hip Knee 17 18 3
Shoulder Joint Shoulder Joint Shoulder Joint: Ball-and-socket Head of humerus and glenoid cavity of scapula Loose joint capsule Ligaments prevent displacement Glenoid labrum Several bursae Very wide range of movement, including rotation, circumduction 19 Major s of the shoulder joint: Coracohumeral Glenohumeral s Transverse humeral 20 Elbow Joint Elbow Joint Elbow Joint: Contains 2 articulations: Hinge joint: - Between trochlea of humerus and trochlear notch of ulna - Flexion / extension only Plane (gliding) joint: - Between capitulum of humerus and fovea on head of radius - Pronation / supination Several reinforcing s Major s of elbow joint: Radial collateral Ulnar collateral Anular 21 22 Hip Joint Hip Joint Hip Joint: Ball-and-socket joint Head of femur and acetabulum of hip bone Acetabular labrum Heavy joint capsule Many reinforcing s Variety of movement, yet less than at shoulder joint Major s of the hip joint: Iliofemoral (strongest in body) Pubofemoral Ischiofemoral 23 24 4
Clinical Application 8.1 Replacing Joints Synthetic materials are used to replace joints damaged by arthritis or injury Steel and titanium replace larger joints, silicone used for smaller joints, some are ceramic Hip replacements are the most common New technology for joint replacement: - Use of materials that resemble natural body chemicals, such as coating implant with hydroxyapatite - 3D printing technology used to create custom replacement joints Knee Joint: Largest & most complex joint 3 bones: Femur: Medial and lateral condyles of distal end Tibia: Medial and lateral condyles of proximal end Patella: Articulates with anterior surface of femur Strengthened by many s and tendons Cushioned by bursae, fat pads Menisci separate femur and tibia Knee Joint 25 26 Knee Joint Major s of the knee joint: Patellar Oblique popliteal Arcuate popliteal Tibial (medial) collateral Fibular (lateral) collateral Anterior cruciate Posterior cruciate Knee joint characteristics: Modified hinge joint between condyles Flexion / extension Some rotation when knee is flexed Plane joint between femur & patella 27 Clinical Application 8.2 Joint Disorders Sprains: Tearing of connective tissue in joint, without bone dislocation Bursitis: Inflammation of a bursa, from overuse or stress Arthritis: Inflammation, swelling, and pain in a joint - Rheumatoid arthritis: autoimmune disease - Osteoarthritis: degenerative, most common type, occurs with aging - Lyme arthritis: caused by Lyme disease, passed through tick bite 28 8.4: Lifespan Changes Joint stiffness is an early sign of aging Many people develop arthritis as they age Fibrous joints first to change; can strengthen, however, over a lifetime Cartilage in synchondroses stiffens Ligaments lose elasticity Changes in symphysis joints of vertebral column diminish flexibility and decrease height (due to water loss from the intervertebral discs) Synovial joints lose function, as capillary supply diminishes Disuse hampers the nutrient supply to joints; speeds up stiffening Activity and exercise can keep joints functional longer 29 5