Articulations PDF

Articulations Objectives Contrast the major categories of joints. Describe the structure of a synovial joint. Describe the dynamic movements of the skeleton. Describe the structure and function of the vertebrae, shoulder, elbow, hip, and knee joints. D...

Articulations Objectives Contrast the major categories of joints. Describe the structure of a synovial joint. Describe the dynamic movements of the skeleton. Describe the structure and function of the vertebrae, shoulder, elbow, hip, and knee joints. Describe the effects of aging and trauma on the joints. Articulations Articulations Where two bones interconnect Immovable joints Synarthroses or bony Slightly moveable joints Amphiarthroses or fibrous/cartilagenous Freely moveable joints Diarthroses or synovial Classification of Joints Synarthroses (immovable joints) Four major types Suture = skull bones bound together by dense connective tissue Gomphosis = teeth bound to bony sockets by periodontal ligaments Synchondrosis = two bones bound by rigid cartilaginous bridge, growth plate Synostosis = two bones completely fused, closed growth plate Amphiarthroses (slightly movable joints) Two major types Syndesmosis = bones connected by a ligament, between interosseous membrane of tibia and fibula Symphysis = bone separated by fibrocartilage, symphysis pubis Diarthroses or Synovial Joints (freely movable joints) Structural components: articular capsule, synovial membrane, and articular (hyaline) cartilage Articular capsule confines joint, grows into periosteum, continuous with tendons and ligaments, regulates range of movement (along with bony projections and tension of tendons) 48  Synovial membrane secretes synovial fluid that lubricates joint and nourishes articular cartilage Articular cartilage covers bone, and regulates growth of epiphyses Bursae and tendon sheaths are synovial membranes outside of a synovial joint Bursitis is an inflamed bursae – housemaid’s or surfer’s knee Types of Joint Movement Flexion – decrease in joint angle Extension – increase in joint angle Hyperextension – extension beyond anatomical position Adduction – movement towards midline Abduction – movement away from midline Medial (external) rotation- anterior surface moves medially Lateral (external) rotation – anterior surface moves laterally Circumduction – movement of ball and socket joint as to make a cone Elevation – shrug shoulders upwards Depression – shrug shoulders downwards Supination – palm of hand facing anteriorly Pronation – palm of hand facing posteriorly Plantar flexion – extension of ankle so as to stand on toes Dorsiflexion – flexion of ankle so as to bring foot towards tibia Inversion – turn foot so as to have sole face medially Eversion – turn foot so as to have sole face laterally Representative Articulations Intervertebral Discs Between bodies of adjacent vertebrae, stabilized by anterior longitudinal ligament and posterior longitudinal ligament. Vertebrae also held together by ligamentum flavum between lamina, interspinous ligament between spinous processes, and supraspinous ligament between tips of spinous processes Structure of disc: nucleus pulposus contained by anulus fibrosus Herniated disc is when nucleus pulposus deforms and compresses nerves. Shoulder joint (glenohumoral joint) Glenoid cavity and head of humerus, ball and socket diarthroses Glenoid fossa is deepened by glenoid labrum Shoulder Dislocation Dislocation of glenohumeral joint Downward blow to humerus with joint abducted and externally rotated (throwing) Glenoid labrum can be damaged, not likely to heal Shoulder Separation Dislocation of acromioclavicular joint Falling on an outstretched arm 49 Knee joint Anterior cruciate ligament Posterior cruciate ligament Medial (tibial) collateral ligament Lateral (fibular) collateral ligament Medial meniscus Lateral meniscus Trauma to knee via lateral blow with planted foot can damage MCL, ACL & medial meniscus (Unhappy Triad) Ankle Joint Lateral malleolus of fibula projects inferior more than medial malleolus of tibia Eversion is more limited Traumatic inversion causes damage to ligaments on lateral ankle (sprained ankle) Traumatic eversion forces tarsals against malleolus causing a broken fibula (broken ankle) Avascular Necrosis Damage to joint that destroys blood vessels that serve the bones Lack of blood supply (avascular) causes death to bone (necrosis) 50