Bio 201 Lecture 5 PDF - Joints

Joints (Articulations) Any point where two bones meet, whether or not the bones are movable at that interface  Joints Athrology - the study of joints Kinesiology - the study of musculoskeletal movement Joint name –derived from bones involved – atlanto-occipital j...

Joints (Articulations) Any point where two bones meet, whether or not the bones are movable at that interface  Joints Athrology - the study of joints Kinesiology - the study of musculoskeletal movement Joint name –derived from bones involved – atlanto-occipital joint, gleno-humeral joint, radio-ulnar joint  Classification Joints are classified by their freedom of movement – Diarthrosis (diarthroses)- freely movable – Amphiarthrosis (amphiarthroses) - slightly movable – Synarthrosis (synarthroses) - little or no movement Joints are also classified by the way adjacent bones are joined – Bony (synostosis) – Fibrous – Cartilaginous – Synovial joints  Joints are also classified by the way adjacent bones are joined: – Bony – Fibrous (synarthroses: little or no movement) Sutures – synarthroses – Serrate sutures – Lap (squamous) sutures – Plane (Butt) sutures Gomphoses - synarthroses Syndesmoses – synarthroses – Cartilaginous Synchondroses Sympheses – Synovial joints  Bony Joints (synostosis) Synostosis (bony joint): 2 bones, once separate, fused by osseous tissue – Ossification occurs with age frontal and mandibular bones in infants cranial sutures in elderly (only) attachment of first rib and sternum with old age infant skull adult skull  Joints are also classified by the way adjacent bones are joined: – Bony – Fibrous Sutures – synarthroses – Serrate sutures – Lap (squamous) sutures – Plane (Butt) sutures Gomphoses - synarthroses Syndesmoses – synarthroses – Cartilaginous Synchondroses Sympheses – Synovial joints  Fibrous Joint (Synarthrosis) Collagen fibers span the space between bones – no joint cavity is present three kinds of fibrous joints – Sutures – synarthroses – Serrate sutures – Lap (squamous) sutures – Plane (Butt) sutures – Gomphoses - synarthroses – Syndesmoses – synarthroses  Fibrous Joint -Gomphoses Fibrous connective tissue Attachment of a tooth to its socket- Gomphoses Peg-in-socket fibrous joint Tooth held in place by fibrous peridontal ligament – collagen fibers that extend from tooth to jawbone – allows the tooth to move a little under the stress of chewing (b) Gomphosis  Fibrous Joint (Synarthrosis) three kinds of fibrous joints – Sutures – synarthroses – Serrate sutures – Lap (squamous) sutures – Plane (Butt) sutures – Gomphoses - synarthroses – Syndesmoses – synarthroses  Fibrous Joint -Syndesmoses 2 bones are bound by longer Fibrous connective tissue collagenous fibers than in a suture or gomphosis – Interosseous membrane Most movable of fibrous joints Interosseous membranes unite – radius to ulna allowing pronation and supination there is some debate as whether or not this is a amphiarthrosis – tibia to fibula limited movement (c) Syndesmosis  Joints are also classified by the way adjacent bones are joined: – Bony – Fibrous Sutures – synarthroses – Serrate sutures – Lap (squamous) sutures – Plane (Butt) sutures Gomphoses - synarthroses Syndesmoses – synarthroses – Cartilaginous Synchondroses Sympheses – Synovial joints  Cartilaginous Joint two bones are linked by cartilage two types of cartilaginous joints – Synchondroses - amphiarthroses – Symphyses - amphiarthroses  Cartilaginous Joint-Synchondroses Cartilaginous joints: bones are bound by Clavicle Sternum hyaline cartilage Rib 1 Costal cartilage – temporary joint in the epiphyseal plate in children binds epiphysis and diaphysis – first rib attachment to sternum other costal cartilages are joined to sternum by Interpubic disc (fibrocartilage) synovial joints Pubic symphysis  Cartilaginous Joint two types of cartilaginous joints – Synchondroses - amphiarthroses – Symphyses - amphiarthroses  Cartilaginous Joint-Symphysis Symphysis means: “Growing together” two bones joined by fibrocartilage – pubic symphysis Intervertebral disc (fibrocartilage) right and left pubic bones joined by interpubic disc – bodies of vertebrae and intervertebral discs Body of vertebra only slight amount of movement between adjacent vertebrae Interpubic disc collective effect of all 23 discs Pubic symphysis (fibrocartilage) gives spine considerable flexibility  Joints are also classified by the way adjacent bones are joined: – Bony – Fibrous Sutures – synarthroses – Serrate sutures – Lap (squamous) sutures – Plane (Butt) sutures Gomphoses - synarthroses Syndesmoses – synarthroses – Cartilaginous Synchondroses Sympheses – Synovial joints  Synovial Joint joint in which two bones are separated by a space called a joint cavity Proximal diarthroses or diarthrodial joints phalanx most familiar type of joint Ligament most are freely movable Periosteum Bone most structurally complex type of joint Middle phalanx most likely to develop painful dysfunction most important joints for physical and occupational therapists, athletic coaches, nurses, and fitness trainers their mobility make them important to quality of life  Synovial Joint anatomy Articular cartilage –hyaline cartilage that covers the facing surfaces of bones Joint (articular) cavity – separates articular surfaces Proximal phalanx Synovial fluid– slippery lubricant Joint cavity Ligament – rich in albumin and hyaluronic containing synovial fluid Articular cartilages acid Periosteum Fibrous capsule Joint Bone viscous, slippery texture like raw Synovial membrane capsule egg whites (albumin) Middle phalanx – nourishes articular cartilage & removes waste – makes movement almost friction free  Synovial Joint anatomy Joint (articular) capsule – connective tissue that encloses the cavity & retains synovial fluid – outer fibrous capsule – continuous with periosteum of Proximal phalanx adjoining bones – inner, cellular, synovial membrane Joint cavity containing Ligament Articular composed mainly of synovial fluid cartilages Fibrous Periosteum fibroblast-like cells that Bone capsule Synovial membrane Joint capsule secrete synovial fluid Middle phalanx macrophages that remove debris  Fibrocartilage grows inward from Fibrocartilage in the joint capsule in a few synovial joints joints – Articular disc forms a pad Femur between articulating bones that crosses the entire joint capsule Joint capsule Articular cartilage temporomandibular joint, distal radioulnar Joint Meniscus cavity joints, sternoclavicular & acromioclavicular joints – Menincus – in the knee, two Tibia cartilages extend inward from (c) Sagittal section the left and right but do not entirely cross the joint absorb shock and pressure guide bones across each other Lateral improve the fit between bones Meniscus stabilize the joints, reducing the chance of dislocation  Tendon Sheaths and Bursae Accessory structures associated with synovial joints – Tendon –strip or sheet of tough, Ulnar bursa (cut) Radial bursa dense-regular collagenous CT that (cut) attaches muscle to bone the most important structures in stabilizing a joint! – Ligament–attaches bone to bone – Bursa – a fibrous sac filled with synovial fluid, located between adjacent muscles, where tendon passes over bone, or between bone Tendon sheaths and skin Tendon sheath (opened) cushion muscles, helps tendons slide more easily over joints, modify direction of tendon pull – Tendon sheets – elongated cylindrical bursae wrapped around a tendon in hands and feet  Exercise and Articular Cartilage Exercise warms synovial fluid Fluid becomes less viscous & more easily absorbed by articular cartilage Cartilage swells & provides a more effective cushion against compression Warm-up period before vigorous exercise helps protect cartilage from wear and tear! Repetitive compression of nonvascular cartilage during exercise squeezes fluid and metabolic waste out of the cartilage When weight removed, cartilage absorbs synovial fluid like a sponge taking in oxygen and nutrients to the chondrocytes Without exercise, cartilage deteriorates more rapidly from inadequate nutrition and waste removal Excessive stress on joints however can lead to osteoarthritis Swimming is a low-impact exercise that does not place undue stress on joints  Classes of Synovial Joints 1. Ball and socket joint 2. Condylar (ellipsoid) joints 3. Saddle joints 4. Plane (gliding) joints 5. Hinge joints 6. Pivot joints  1. Ball-and-socket Joints Smooth, hemispherical head fits within a cuplike socket – shoulder joint - head of humerus fit into glenoid cavity of scapula – hip joint - head of femur into acetabulum of hip bone The only multiaxial joints in the body  Movement of Synovial Joints Vocabulary of movements of Synovial Joints – used in kinesiology, physical therapy, etc – many presented in pairs with opposite or contrasting meanings – need to understand anatomical planes and directional terms Zero position– the position of a joint when a person is in the standard anatomical position – joint movements are described as deviating from the zero position or returning to it  Flexion, Extension and Hyperextension Flexion – movement that Flexion decreases the a joint angle – common in hinge joints Extension Extension – movement that straightens a joint and generally returns a body part to the zero position Hyperextension Hyper extension – further extension of a joint beyond the zero position Extension – flexion and extension occur at nearly all diarthroses, hyperextension is limited to a few Flexion Flexion, Extension and Hyperextension Flexion Hip flexion Hyperextension Knee flexion Extension  Abduction and Adduction (a) Abduction (b) Adduction Abduction - movement of a body part in the frontal plane away from the midline of the body – hyperabduction – raise arm over back or front of head Adduction - movement in the frontal plane back toward the midline – hyperadduction – crossing fingers, crossing ankles  Elevation and Depression (a) Elevation (b) Depression Elevation - a movement that raises a body part vertically in the frontal plane Depression – lowers a body part in the same plane  Protraction and Retraction Protraction – anterior movement of a body part in the (a) Protraction transverse (horizontal) plane Retraction – posterior movement (b) Retraction  Circumduction One end of an appendage remains stationary while the other end makes a circular motion – Finger, hand, thigh, foot, trunk, head Sequence of flexion, abduction, extension and adduction movements – baseball player winding up for a pitch  Rotation Rotation – movement in which a bone spins on its longitudinal axis – rotation of trunk, thigh, head or arm Medial (internal) rotation turns the bone inwards Lateral (external) rotation turns the bone outwards (a) Medial (internal) rotation (b) Lateral (external) rotation  Supination and Pronation Supination – forearm movement that turns the palm to face anteriorly or upward – forearm supinated in anatomical position – radius is parallel to the ulna Pronation – forearm movement that turns the palm to face posteriorly or downward – radius spins on the capitulum of the humerus – disc spins in the radial notch of ulna – radius crosses stationary ulna (a) Supination (b) Pronation like an X  Movements of Head and Trunk (a) Flexion (b) Hyperextension (c) Lateral flexion Flexion, hyperextension, and lateral flexion of vertebral column  Common Joint Injuries Sprain – Ligaments are stretched or torn – Heal slowly – poorly vascularized – Completely torn – surgery or replacement cartilage Injuries – Remain torn due to avascularization Arthroscopic surgery to remove damaged tissue Joint is less stable after removal Dislocations (luxation) – Bones are forced out of alignment – Must be reduced Bones returned to normal position  Knee Injuries Highly vulnerable to rotational and horizontal stress Twisting motion Most common injuries are to the meniscus and anterior cruciate ligament (ACL) heal slowly due to scanty blood flow Foot fixed Arthroscopy – procedure in which the interior of the joint is viewed with a pencil-thin arthroscope inserted through a small incision – less tissue damage than conventional Anterior cruciate ligament (torn) surgery Tibial collateral ligament (torn) – recovery more quickly Medial – graft from patellar ligament or hamstring meniscus (torn) tendon is often used Patellar ligament  Inflammatory & Degenerative Conditions Bursitis – inflammation of a bursa – Usually caused by a blow or friction Tendonitis – inflammation of tendon sheaths Arthritis - a broad term for pain & inflammation – most common crippling disease in the United States – Rheumatologists – physicians who treat arthritis and other joint disorders – Osteoarthritis – Rheumatoid Arthritis (RA) – Gouty Arthritis (Gout)  Osteoarthritis Osteoarthritis– most common form of arthritis – ‘wear-and-tear arthritis’ – results from years of joint wear – articular cartilage softens and degenerates – accompanied by crackling sounds called crepitus – bone spurs develop on exposed bone tissue causing pain – rarely occurs before age 40 – affects 85% of people over 70 years old – Obesity is a risk factor – joints of fingers, intervertebral, hips and knees are most likely areas of OA  Rheumatoid Arthritis Rheumatoid arthritis (RA) - autoimmune attack against the joint tissues – misguided antibodies (rheumatoid factor) attack synovial membrane – enzymes in synovial fluid degrade the articular cartilage – joint begins to ossify – ankylosis – solidly fused, immobilized joint – remissions occur – steroids and aspirin control inflammation  Gouty Arthritis (Gout) Hereditary disease – More common in men – Metabolic disorder - excess uric acid build-up Uric acid– normal waste product excreted in urine Excessive production or slow excretion Urate crystals form in soft tissues and joints – pain Great toe most affected