CHS Anatomy and Physiology Name____________________________ Unit 6 – Class Notes The Joints Date________ Functions of Joints 1. Articulations of bones (points of contact) →hold bones together 2. Allow for mobility →Joints are classified in two ways… 1. structurally – based on anatomical characteristics 2. functionally – based on the type of movement they permit Structural Classification of Joints →Based on… 1. the presence or absence of a synovial cavity (space between articulating bones) 2. the type of connective tissue that holds the bones together 1. Fibrous joints – no synovial cavity →generally immovable →held by dense irregular connective tissue 2. Cartilaginous joints – no synovial cavity →immovable or slightly moveable →held by cartilage 3. Synovial joints – have a synovial cavity →freely moveable →held by dense irregular connective tissue and ligaments Functional Classification of Joints 1. Synarthroses - immovable joints (ex. fibrous synarthroses = skull sutures and teeth cartilage synarthroses = epiphyseal plates) 2. Amphiarthroses - slightly moveable joints (ex. fibrous amphiarthroses = distal ulna and radius cartilage amphiarthroses = vertebral discs) 3. Diarthroses - freely moveable joints (ex. all diarthrotic joints are synovial joints and synovial joints are all diarthrotic) Fibrous Joints - bones united by fibrous tissue →permit little or no movement 1. sutures – unite bones of the skull →irregular, interlocking edges give them added strength 2. syndesmoses – greater distance between bones →allows more movement than sutures →tissue arranged as a bundle or ligament (ex. distal end of tibia and fibula) 3. interosseous membrane – sheet of tissue that binds neighboring bones (ex. between tibia and fibula, radius and ulna Cartilaginous Joints - bones connected by cartilage 1. synchondrosis – connecting material is hyaline cartilage →immovable joint (ex. epiphyseal plate) 2. symphysis – bones are connected with a broad, flat disc of fibrocartilage →slightly moveable joint (ex. pubic symphysis, intervertebral joints) Synovial Joints – a fully movable joint iin which a synovial cavity is present between two articulating bones Features of Synovial Joints 1. Articulating bones are separated by a joint cavity filled with synovial fluid 2. Articular cartilage (hyaline cartilage) covers the ends of bones 3. A fibrous articular capsule encloses joint surfaces 4. Ligaments reinforce the joint Structures Associated with the Synovial Joint 1. tendons – a fibrous cord of connective tissue that attaches bone to muscle 2. ligaments – connective tissue that attaches bone to bone 3. articular discs (meniscus) – fibrocartilage pad between bone surfaces 4. bursae—flattened fibrous sacs used to reduce friction in the joint →lined with synovial membranes and filled with synovial fluid →not actually part of the joint 5. tendon sheath - elongated bursa that wraps around a tendon Types of Movement at Synovial Joints (see pages 170-173) 1. gliding – simple movement of flat bones back-and-forth relative to each other (ex. between carpal bones of wrist) 2. angular movements – occur when there is an increase or decrease in the angle between articulating bones (ex. flexion (decease angle) and extension (increase angle)) 3. rotation – bone revolve around it’s own longitudinal axis (ex. turning head from side to side) 4. special movements – can only occur at specific joints a. elevation – upward movement of a part of the body (ex. closing mouth, shrugging shoulders) b. depression – downward movement of a part of the body (ex. opening mouth) c. protraction – movement of a part of the body forward (ex. thrusting mandible outward) d. supination – movement of forearm so that the palm is turned forward e. opposition – movement of thumb across the palm to touch the tips of fingers →this distinct digital movement allows primates to grasp and manipulate objects Types of Synovial Joints (page 174) 1. plane joint – permit back-and-forth and side-to-side movements between the flat surfaces of bones (ex. carpal bones of wrist) 2. hinge joint – produce angular motion (ex. knee and elbow) 3. pivot joint – allows rotation around its own longitudinal axis (ex. turning your head from side-to-side) 4. condyloid joint – permits movement around two axes. (ex. between radius and carpals) 5. saddle joint – permits movements around three axes (ex. metacarpel of thumb meets carpals) 6. ball-and-socket joint – also permits movements around three axes (ex. shoulder and hip) Major parts of the knee joint 1. anterior cruciate ligament (ACL) – limits hyperextension of the knee and prevents anterior sliding of tibia on femur →70% of all serious knee injuries are caused by ACL strains or tears 2. posterior cruciate ligament (PCL) – prevents posterior sliding of tibia on femur 3. medial collateral ligament – strengthens middle of knee 4. lateral collateral ligament – strengthens outer sides of knee 5. menisci – fibrocartilage discs between tibia and femur →help compensate for irregular bone shapes →largest and most complex joint of the body Arthroplasty – surgical replacement of severely damaged natural joints with artificial joints →knee, hip, shoulder are most common →metal, ceramic or plastic components replace bone Steps to Knee Replacement (page 178) 1. Damages cartilage is removed from the ends of bones 2. The femur is reshaped, fitted with a metal component and cemented in place 3. The tibia is reshaped, fitted with a plastic component and cemented in place 4. If the back surface of the patella is damaged, it is replaced with a plastic patellar component Common Joint Injuries 1. bursitis—inflammation of synovial membranes (bursa) that lie between muscle and bone →usually caused by a blow or friction 2. tendonitis—inflammation of tendon sheaths 3. rotator cuff injury – strain or tear of the rotator cuff muscles 4. separated shoulder – damage to the acromioclavicular joint →not the same as a dislocated shoulder 5. sprain – stretching, tearing or damaging to ligaments and tendons that stabilize a joint, but does not dislocate the bone →the ankle joint is the most commonly sprained →damage may also occur to surrounding blood vessels, muscles and nerves 6. strain – a stretched or partially torn muscle →occurs when muscles are forced to contract suddenly 7. carpal tunnel syndrome – a repetitive motion injury in which pressure develops on the median nerve →pressure may cause numbness, tingling or pain in the fingers Arthritis—inflammatory or degenerative diseases of joints →over 100 different types →the most widespread crippling disease in the United States 1. Osteoarthritis – erosion of the articular cartilages due to normal wear and tear over time →most common type of chronic arthritis 2. Rheumatoid arthritis – inflammation of the synovial joints →an autoimmune disease—the immune system attacks the joint membranes →symptoms begin with bilateral inflammation of certain joints →often leads to deformities Ganglion cysts – noncancerous fluid-filled lumps (cysts) that most commonly develop along tendons sheaths or joints of your wrists, hands or feet →the exact cause of a ganglion cyst is unknown →occur when the tissue that surrounds a joint or a tendon sheath bulges out of place →inside the cyst is a thick fluid similar to synovial fluid found in joints or around tendons →will usually go away on their own, however, can be drained or surgically removed if painful .