Joints or Articulations 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 Joints-Structural and Functional Fibrous Joints-lack a synovial cavity and permit little to no movement dense connective tissues connect bones between bones in close contact synarthrotic immovable amphiarthrotic slightly movable diarthrotic freely movable 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 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 Condyloid Joint between metacarpals and phalanges Oval shaped projection fits into oval shaped depression Ball-and-Socket Joint hip shoulder Permit multiaxial movement 8-9

Types of Synovial Joints Gliding Joint or Planar Joints between carpals between tarsals Articular surfaces are flat to slightly curved Hinge Joint elbow between phalanges 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 friction-look up names…… ligaments prevent displacement very wide range of movement Rotator cuff- supraspinatus, infraspinatus, teres minor, subscapularis, work together to join scapula to humerus 8-15

Shoulder Joint 8-16

Elbow Joint hinge joint gliding joint flexion and extension 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 ligaments-like 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