Chapter 08 Lecture Outline See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes.

Introduction 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

8.1: Types of Joints Structural Classification of Joints: Fibrous Cartilaginous Synovial Functional Classification of Joints: Synarthrotic—immovable Amphiarthrotic—slightly movable Diarthrotic—freely movable

Fibrous Joints 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 ligament) Amphiarthrotic (flexible, may twist) Lies between tibia and fibula

Fibrous Joints Suture: Gomphosis: Between flat bones of skull Thin layer of connective tissue (sutural ligament) connects bones Synarthrotic (immovable) Gomphosis: Cone-shaped bony process in a socket in jawbone Tooth in jawbone by periodontal ligament Synarthrotic (immovable)

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)

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 Synovial Joints: Most joints are synovial joints All are diarthrotic joints Structure of s synovial joint: Articular cartilage covers articular ends of bones Joint capsule, consists of 2 layers: Outer fibrous layer, composed of ligaments Inner layer, synovial membrane, which secretes synovial fluid

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

Types of Synovial Joints 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

Types of Synovial Joints 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

Types of Synovial Joints 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: Types of Joint Movements 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

Types of Joint Movements Abduction / adduction Flexion / extension / hyperextension Lateral flexion

Types of Joint Movements Dorsiflexion / plantar flexion Circumduction / rotation Medial rotation / lateral rotation Supination / pronation

Types of Joint Movements 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

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

Shoulder Joint Major ligaments of the shoulder joint: Coracohumeral ligament Glenohumeral ligaments Transverse humeral ligament

Elbow Joint Elbow Joint: Hinge joint: Plane (gliding) 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 ligaments

Elbow Joint Major ligaments of elbow joint: Radial collateral ligament Ulnar collateral ligament Anular ligament

Hip Joint Hip Joint: Ball-and-socket joint Head of femur and acetabulum of hip bone Acetabular labrum Heavy joint capsule Many reinforcing ligaments Variety of movement, yet less than at shoulder joint

Hip Joint Major ligaments of the hip joint: Iliofemoral ligament (strongest ligament in body) Pubofemoral ligament Ischiofemoral ligament

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 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 ligaments and tendons Cushioned by bursae, fat pads Menisci separate femur and tibia

Knee Joint Major ligaments of the knee joint: Patellar ligament Oblique popliteal ligament Arcuate popliteal ligament Tibial (medial) collateral ligament Fibular (lateral) collateral ligament Anterior cruciate ligament Posterior cruciate ligament Knee joint characteristics: Modified hinge joint between condyles Flexion / extension Some rotation when knee is flexed Plane joint between femur & patella

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

8.4: Life-Span 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