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Chapter 8 Joints or Articulations Why do we need them? • Articulations are junctions between bones • They 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 contraction 8-2 Classification of JointsStructural and Functional • Fibrous Joints-lack a synovial cavity and permit little to no movement • dense connective tissues connect bones • between bones in close contact • Cartilaginous Joints-lack a synovial cavity and allow little or no movement • hyaline cartilage or fibrocartilage connect bones form a tight connection • Synovial Joints-have a joint cavity • most complex • allow free movement • synarthrotic • immovable • amphiarthrotic • slightly movable • diarthrotic • freely movable 8-3 Fibrous Joints 3 Types • Syndesmosis • Suture • Gomphosis Syndesmosis • long fibers connect bones • amphiarthrotic • distal ends of tibia and fibula 8-4 Fibrous Joints Suture • between flat bones (skull) • synarthrotic • thin layer of connective tissue connects bones •Metopic suture of frontal bone usually fuses completely Gomphosis • cone-shaped bony process in a socket • tooth in jawbone • synarthrotic 8-5 Cartilaginous Joints 2 Types • Synchondrosis • Symphysis Synchondrosis • bands of hyaline cartilage unite bones • epiphyseal plate (temporary) • between manubrium and first rib • synarthrotic (immoveable) 8-6 Cartilaginous Joints Symphysis • pad of fibrocartilage between bones • pubis symphysis • joint between bodies of vertebrae • amphiarthrotic 8-7 Synovial Joints • diarthrotic • joint cavity allows joint to move freely • synovial fluid-reduce friction, absorb shocks, supply oxygen and remove waste from chondrocytes • joint capsule • synovial membrane-inner layer of the articular capsule •Articular cartilage covers ends • bursae-reduce friction, cushion movement 8-8 Types of Synovial Joints Ball-and-Socket Joint • hip • shoulder •Permit multiaxial movement Condyloid Joint • between metacarpals and phalanges •Oval shaped projection fits into oval shaped depression 8-9 Types of Synovial Joints Gliding Joint or Planar Joints Hinge Joint • between carpals • elbow • between tarsals • between phalanges •Articular surfaces are flat to slightly curved 8-10 Types of Synovial Joints Pivot Joint • between proximal ends of radius and ulna and between axis and atlas Saddle Joint • between carpal and metacarpal of thumb •Modified condylar joint 8-11 Types of Joint Movements • abduction- movement away from midline •Adduction-movement toward midline • dorsiflexion-bend the foot at the ankle (stand on heels) •Plantarflexion-bend foot at ankle toward inferior (stand on toes) • flexion-decrease the angle •Extension-increase angle of joint •Hyperextension-continue extension beyond anatomical position 8-12 Types of Joint Movements • rotation-bone turns on longitudial axis •Circumduction-one end remains stationary • supination –palm is up (hold soup) •pronation-palm is down or facing the rear 8-13 Types of Joint Movements • eversion-turning sole of foot laterally • inversion-turning sole medially • protraction-/retraction • elevation/depression 8-14 Shoulder Joint • ball-and-socket • head of humerus and glenoid cavity of scapula • loose joint capsule • 4 bursae reduce frictionlook up names…… • ligaments prevent displacement • very wide range of movement •Rotator cuff- supraspinatus, infraspinatus, teres minor, subscapularis, work together 8-15 Shoulder Joint 8-16 Elbow Joint • hinge joint • trochlea of humerus • trochlear notch of ulna • gliding joint • capitulum of humerus • head of radius • flexion and extension • many reinforcing ligaments •Including radial collateral ligament and ulnar collateral ligament • stable joint 8-17 Elbow Joint 8-18 Hip Joint • ball-and-socket joint • head of femur • acetabulum •Acetabular labrum is a fibrocartilage rim that increases depth of socket • heavy joint capsule • many reinforcing ligamentslike ischiofemoral and iliofemoral ligament • less freedom of movement than shoulder joint 8-19 Hip Joint 8-20 Knee Joint • largest joint and most complex • medial and lateral condyles of distal end of femur • medial and lateral condyles of proximal end of tibia • femur articulates anteriorly with patella • modified hinge joint • flexion/extension/little rotation • strengthened by many ligaments and tendons-PCL, ACL, tibial collateral ligament, fibular collateral ligament, • menisci separate femur and tibia • bursae include pre-patellar bursae which is often damaged when you bump the anterior knee 8-21 Knee Joint 8-22 Life-Span Changes • Joint stiffness is an early sign of aging • Regular exercise can prevent stiffness • Fibrous joints first to strengthen over a lifetime • Changes in symphysis joints of vertebral column diminish flexibility and decrease height • Synovial joints lose elasticity 8-23 Clinical Application Joint Disorders Sprains • damage to cartilage, ligaments, or tendons associated with joints • forceful twisting of joint Bursitis • inflammation of a bursa • overuse of a joint Arthritis • inflamed, swollen, painful joints • Rheumatoid Arthritis-RA, autoimmune disease •Osteoarthritis or OA-most common, wear and tear • Gout-often strikes big toe, peanuts can aggravate this 8-24 Disorders • Cartilage injury-usually require surgery • Dislocation (luxation)-forced bone out of alignment, usually downward displacement • Partial dislocation is subluxation • Bursitis-also known as: housemaids knee, tennis elbow, student elbow (olecranon bursitis) • Tendonitis-inflammation of tendon sheath, same type symptoms as bursitis
