Chapter 9 Articulations

How flexible are we?

Articulation = joints

Classification of Joints Structural - named according to presence of fluid filled joint capsule or type of connective tissue Functional - named according to degree of movement allowed Synarthroses—immovable joint Amphiarthroses—slightly movable Diarthroses—freely movable (synovial joints)

Fibrous joints - synarthroses - bones fit together closely Syndesmoses - joints in which ligaments connect 2 bones Sutures - found in skull Gomphoses - between root of tooth and mandible or maxilla

Cartilagenous joints Bones are joined together by hyaline cartilage or fibrocartilage hyaline present between articulating bones. Symphyses - joints in which pad or disk of fibrocartilage connects two bones.

Synovial joints (diarthroses)(freely movable) freely movable joints Joint capsule- binds together Synovial membrane - lines capsule Articular cartilage - covers bones Joint cavity - space between bones Menisci (articular disks) Ligaments - hold bones together Bursae - filled with fluid

Cadaver joint

Types of synovial joints Uniaxial joints Hinge joints - allows flexion and extension Finger, elbow Pivot joint - projection articulates with notch of other bone - ex. First/second cervical vertebrae Biaxial joints Saddle joints - only in thumb Condyloid (ellipsoidal) joints - between radius/carpals Multiaxial joints Ball and socket - shoulder and hip Gliding joint - between vertebrae, carpals and tarsals

Shoulder joint - Humeroscapular joint Most mobile Ligaments - hold together bones Tendons - attach muscle to bone Bursae - contain fluid - shock absorption

Shoulder joint

Ball broken off humerus

Rotator cuff tears

Shoulder Replacement surgery

Elbow joint - Classic hinge joint Two bones coming together with one bone Stabilization by collateral ligaments Surrounded by joint capsule Olecranon bursa - protection Trauma to nerve - “funny bone”/dropped wrist Proximal radioulnar joint - permits forearm rotation

Wrist joints - Radiocarpal Radius articulates with carpal bones Joint - synovial

Intercarpal joints Between 8 carpal bones Stabilization by ligaments Movements - gliding, with some abduction and flexion

Carpometacarpal joints three joints 1 Thumb joint Fingers - two joints—movements - gliding type Thumb joint is unique and important functionally joint capsule is loose fitting Saddle-shaped - allowing for opposition Movements— extension, adduction, abduction, circumduction, opposition - opposable thumb

Metacarpophalangeal joints Rounded heads of metacarpals articulate with concave bases of proximal phalanges Strengthened by collateral ligaments movements - flexion and extension

Interphalangeal joints hinge-type, synovial between heads of phalanges / distal phalanges

Hip joint Hip Joint Stable joint (because of head of femur and acetabulum A joint capsule / ligaments contribute to stability

Hip surgery

Knee joint Largest / most complex most frequently injured joints Tibiofemoral joint - supported by ligaments, cartilage, joint capsule Permits flexion and extension

ACL

Knee Replacement surgery

Knee resurfacing surgery

Ankle joint Hinge type synovial joint Articulation - tibia and fibula articulate with talus wedge-shaped Lateral malleolus lower than medial

Ankle injuries “sprained ankle” Involves anterior talofibular ligament External ankle rotation injuries generally involve bone fractures rather than ligament tears First-degree ankle injury—lateral malleolus fractured Second-degree ankle injury—both malleoli fractured Third-degree ankle injury—fracture of both malleoli and articular surface of tibia

Vertebral joints Vertebral column Intervertebral disks - between vertebrae Ligaments - supporting vertebrae

Types and Range of Movement at Synovial Joints Measuring range of motion (ROM) Assessment of ROM active or passive measurement goniometer

Joint movement (Extension, flexion and rotation)

Joint movement - hyperextension, abduction, adduction

Joint movement - flexion, extension supination and pronation

Joint movement - dorsiflexion, plantar flexion, eversion, inversion, adduction and abduction of ankle

Joint movement - protraction, retraction, elevation and depression

Cycle of Life: Articulations Bone development and the sequence of ossification between birth and skeletal maturity affect joints Fontanels between cranial bones disappear Epiphysial plates ossify at maturity Older adults ROM decreases Changes in gait occur Skeletal diseases manifest as joint problems Abnormal bone growth (lipping)—influences joint motion Disease conditions can be associated with specific developmental periods

Rheumatoid arthritis and osteoarthritis

Caring for your joints Maintain ideal body weight Move your body Stand up straight Use big joints when lifting Pace yourself Listen to your body Don’t be static Sit on the floor when you can Prepare yourself for activities Wear safety equipment Ask for help