BIO 201: Joints and Articulations
BIO 201: Joints and Articulations BIO 201
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This 11 page Class Notes was uploaded by ASUNursing19 on Saturday March 26, 2016. The Class Notes belongs to BIO 201 at Arizona State University taught by Dr. Penkrot in Winter 2016. Since its upload, it has received 37 views. For similar materials see Human Anatomy/Physiology I in Biology at Arizona State University.
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Date Created: 03/26/16
Joints Joints and Their Classification o Bony joints o Fibrous joints o Cartilaginous joints Synovial Joints o General anatomy o Joints and lever systems o Movements of synovial joints Anatomy of Selected Diarthroses Joints (Articulations) Joint (Articulation): any point where two bones meet, whether or not the bones are movable at that interface Arthrology: science of joint structure, functions, and dysfunction Kinesiology : the study of musculoskeletal movement o A branch of biomechanics deals with a broad variety of movements and mechanical processes in the body, including the physics of blood circulation, respiration, and hearing Applied Kinesiology *NOT* the same thing as kinesiology! Joints and Their Classification Joint name typically derived from the names of the bones involved o Atlantooccipital joint, glenohumeral joint, radioulnar joint,… o Joints classified according to the manner in which the adjacent bones are bound to each other, with differences in how freely the bones can move o Joints Classifications: these classifications vary by discipline and application Joint Classifications Structural o Fibrous: joined by fibers o Cartilagenous: cartilage pad o Synovial: liquid filled Functional o Synarthrosis: no movement Synostosis (fused bone), gomphosis, sutures, syndesmosis o Amphiarthrosis: little movement Synchondrosis, symphysis o Diarthrosis: significant movement possible Synovial Bone Joint Synostosis Bony joint , or ynostosis: an immovable joint formed when the gap between two bones ossify, and they become in effect, a single bone o Can be normal or pathological o Frontal and mandibular bones in infants o Cranial sutures in elderly o Attachment of first rib and sternum with old age Occur most often in either fibrous or cartilaginous joint Synostosis Pathology Cleft palate and hare lip Fibrous Joints Synarthrosis Fibrous joint, ynarthrosis , or synarthrodial joint a point at which adjacent bones are bound by collagen fibers that emerge from one bone, cross the space between them, and penetrate into the other o Can form synostoses (pathologically) Three kinds of fibrous joints o Sutures o Gomphoses o Syndesmoses Fibrous Joints Sutures Sutures : immovable or only slightly moveable fibrous joints that closely bind the bones of the skull to each other Sutures can be classified as: o Serrate: interlocking wavy lines Coronal, sagittal and lambdoid sutures o Lap (Squamous): overlapping beveled edges Temporal and parietal bones o Plane (butt): straight, nonoverlapping edges Palatine processes of the maxillae Fibrous Joints Gomphoses Gomphosis: attachment of a tooth to its socket (alveolus) Held in place by fibrous periodontal ligament (collagen) Does allow a tiny amount of tooth movement in the alveolus Fibrous Joint Syndesmosis Syndesmosis : a fibrous joint at which two bones are bound by longer collagenous fibers than in a suture or gomphosis giving the bones more mobility o Interosseous membrane Most moveable syndesmosis o Interosseus membranes unite radius to ulna allowing supination and pronation (rotation of radius) Less movable syndesmosis o Tibia to fibula Cartilaginous Joints Cartilaginous joint , phiarthrosis or amphiarthrodial joint : two bones are linked by cartilage Two types of cartilaginous joints o Synchondroses (connected by hyaline cartilage) Example: first rib to sternum o Symphyses (connected by fibrocartilage) Example: pubic symphysis Cartilaginous Joints Synchondrosis Synchondrosis: bones are bound by hyaline cartilage o Temporary joint in the epiphyseal joint in children Binds epiphysis and diaphysis o First rib attachment to sternum Other costal cartilages are joined to sternum by synovial joints Cartilaginous Joint Symphysis Symphysis : two bones joined by fibrocartilage o Pubic symphysis in which right and left pubic bones joined by interpubic disc o Bodies of vertebrae and intervertebral discs Only slight amount of movement between adjacent vertebrae Collective effect of all 23 discs gives spine considerable flexibility Synovial Joint Diarthrosis Synovial joint, diarthrosis or diarthrodial joint: joint in which two bones are separated by a space called a joint cavity Most familiar type of joint Most are freely movable Most structurally complex type of joint and most likely to develop painful dysfunction General Anatomy Synovial Joint Articular cartilage: layer of hyaline cartilage that covers the facing surfaces of two bones o Protects ends of bones; lack of articular cartilage > arthritis Joint (articular) cavity: separates articular surfaces Synovial fluid : slippery lubricant in joint cavity o Rich in albumin and hyaluronic acid o Gives it a viscous, slippery texture like raw egg whites o Nourishes articular cartilage and removes waste o Makes movement of synovial joints almost friction free less friction than ice moving against ice Joint (articular) capsule: connective tissue that encloses the cavity and retains the fluid o Outer fibrous capsule: continuous with periosteum of bones o Inner, cellular, synovial membrane: composed mainly of fibroblastlike cells that secrete synovial fluid and macrophages that remove debris from the joint cavity In a few synovial joints, fibrocartilage grows inward from the joint capsule o Articular disc forms a pad between articulating bones that crosses the entire joint capsule Example: temporomandibular joint o Meniscus : in the knee, two cartilages extend inward from the left and right but do not entirely cross the joint These cartilages absorb shock and pressure Guide bones across each other Improve the fit between bones and stabilize the joints, reducing the chance of dislocation Accessory structures associated with synovial joints o Tendon: a strip or sheet of tough collagenous connective tissue that attaches muscle to bone making it the most important structures in stabilizing a joint o Ligament: similar tissue that attaches one bone to another o Bursa : a fibrous sac filled with synovial fluid, located between adjacent muscles, where tendon passes over bone, or between bone and skin o Tendon sheaths : elongated cylindrical bursae wrapped around a tendon Synovial Joints: General Structure Synovial joints all have o Articular cartilage o Joint (synovial) cavity o Articular capsule o Synovial fluid o Reinforcing ligaments Factors Influencing Stability of Synovial Joints Three factors determine stability of joints to prevent dislocations: 1. Shape of articular surface (minor role) Shallow surfaces less stable than ballandsocket 2. Ligament number and location (limited role) The more ligaments, the stronger the joint 3. Muscle tone keeps tendons taut as they cross joints (most important) Extremely important in reinforcing shoulder and knee joints and arches of the foot Exercise and Articular Cartilage Exercise warms synovial fluid and it becomes less viscous and more easily absorbed by articular cartilage Cartilage then swells and provides a more effective cushion against compression Warmup period before vigorous exercise helps protect cartilage from undue wear and tear Repetitive compression of nonvascular 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 Range of Motion Range of motion (ROM) : the degrees through which a joint can move o An aspect of joint performance o Physical assessment of a patient's joint flexibility Range of motion determined by: o *structure of the articular surfaces* Elbow: olecranon of ulna fits into olecranon fossa of humerus o Strength and tautness of ligaments and joint capsules Stretching of ligaments increases range of motion "doublejointed" people have long or slack ligaments o Action of the muscles and tendons Nervous system monitors joint position and muscle tone Muscle tone : state of tension maintained in resting muscles Movements Allowed by Synovial Joints All muscles attach to bone or connective tissue at no fewer than two points o Origin: attachment to immovable bone o Insertion: attachment to movable bone Muscle contraction causes insertion to move toward origin Movements occur along transverse, frontal, or sagittal planes Range of motion allowed by synovial joints: o Nonaxial : slipping movements only o Uniaxial: movement in one plane o Biaxial: movement in two planes o Multiaxial: movement in or around all three planes Three general types of movements: o Gliding o Angular ovements o Rotation Axes of Rotation A moving bones has a relatively stationary axis of rotation that passes through the bone in a direction perpendicular to the plane of movement Multiaxial joint: shoulder joint has three degrees of freedom or axes of rotation Other joints: monoaxial or biaxial Movement of Synovial Joints Vocabulary of movements of synovial joints used in kinesiology, physical therapy, and other medial fields o Many presented in pairs with opposite or contracting meanings o Need to understand anatomical planes and directional terms Zero position : the position of a joint when a person is in the standard anatomical position o Joint movement are described as deviating from the zero position or returning to it Types of Synovial Joints There are six different types of synovial joints o Categories are based on shape of articular surface, as well as movement joint is capable of Plane Hinge Pivot Condylar Saddle Ballandsocket Glenohumeral Joint Ballandsocket joint but not much of a socket o Large, round humeral head on small, flat glenoid cavity of scapula o Rotator cuff muscles do most work of holding the upper limb onto the body SITS: suprspinatus m., infraspinatus m., teres minor m., subscapularis m. o A few ligaments Most mobile major joint in the body, but also the weakest Long head of the biceps brachii m. also originates practically inside the joint cavity Shoulder (Glenhumeral) Joint Most freely moving joint in body Stability is sacrificed for freedom of movement Ballandsocket joint o Large, hemispherical head of humerus fits in small, shallow glenoid cavity of scapula Like a gold ball on a tree Articular capsule enclosing cavity is also thin and loose o Contributes to freedome of movent Acetabulofemoral Joint Ballandsocket joint Typically very strong o Femoral head fits snugly inside acetabular cavity o Large, tough ligaments and muscles help stabilize the joint o Dislocation very unlikely fracture of femoral neck more likely Dislocation easier when hip flexed and strong force is applied to knee, as in a car accident Iliofemoral ligament toughest in body o Tear of round ligament (fovea capitis) can lead to necrosis of femoral head Elbow Joint(s) Both pivot (humeroradial) and hinge (humeroulnar) joints are represented o Radioulnar joint Numerous ligaments help stabilize these joints o Ulna can become dislocated from trochlea of distal humerus o Radium can become dislodged from the anular ligament that stabilizes it during rotation "nursemaid's elbow" Knee Femorotibial joint (condylar joint) o Tibiofibular joint o Femoropatellar joint Largest and most complex synovial joint in the body o Anterior cruciate ligament (ACL) & posterior cruciate ligament (PCL) o Medial (tibial) and lateral (fibular) collateral ligaments o Menisci Medial meniscus is attached to medial collateral ligaments Temporomandibular Joint Condylar joint Stabilized by several small ligaments and muscles of mastication TMD: temporomandibular joint disorder o Complex disorder resulting in general and/or localized pain near the jaw joint, chronic pain, and possibly progressive damage Arthritis of the TMJ o Articular disc/meniscus can become displaced o The TMJ actually has to disarticulate slightly every time the mandible is depressed completely (mouth opened completely) makes the joint susceptible to problems Condylar process of mandible rides out of the mandibular fossa anteriorly upon opening mouth completely Ankle and Foot Joints Ankle joint itself is essentially a condylar joint o Tibiotalar o Calcaneofibular ligament stronger than distal fibula bad sprain can tear off lateral malleolus of fibula Joints between tarsal (or carpal, if in the wrist) bones are planar o Very little if any movement normally o Held in place with numerous ligaments Metatarsal (or metacarpal)/phalangeal joints are condylar primarily 8.6 Disorders of Joints Common Joint Injuries Cartilage tears o Due to compression and shear stress o Fragments may cause joint to lock or bind o Cartilage rarely repairs itself o Repaired with arthroscopic surgery o Partial menisci removal renders joint less stable but mobile; complete removal leads to osteoarthritis o Meniscal transplant possible in younger patients o Perhaps meniscus grown from own stem cells in future Sprains o Reinforcing ligaments are stretched or torn o Common sites are ankle, knee, and lumbar region of back o Partial tears repair very slowly because of poor vascularization o Three options if torn completely Ends of ligaments can be sewn together Replaced with grafts Just allow time and immobilization for healing Dislocations (luxations) o Bones forced out of alignment o Accompanied by sprains, inflammation, and difficulty moving joint o Caused by serious falls or contact sports o Must be reduced to treat Subluxation : partial dislocation of a joint Inflammatory and Degenerative Conditions Bursitis o Inflammation of bursa, usually caused by blow or friction o Treated with rest and ice and, if severe, antiinflammatory drugs Tendonitis o Inflammation of tendon sheaths, typically caused by overuse o Symptoms and treatment similar to those of bursitis Arthritis o >100 different types of inflammatory or generative diseases that damage joint o Most widespread crippling disease in the U.S. o Symptoms: pain, stiffness, and swelling of joint o Acute forms: caused by bacteria, treated with antibiotic o Chronic forms: osteoarthritis, rheumatoid arthritis, and gouty arthritis Osteoarthritis (OA) o Most common type of arthritis o Irreversible, degenerative ("wearandtear") arthritis o May reflect excessive release of enzymes that break down articular cartilage Cartilage is broken down faster than it is replaced Bone spurs (osteophytes) may form from thickened ends of bones Results in crepitus o By age 85, half of Americans develop OA, more women than men o OA is usually part of normal aging process o Joints may be stiff and make crunching noise referred tcrepitus, especially upon rising o Treatment: moderate activity, mild pain relievers, capsaicin creams Glucosamine, chondroitin sulfate, and nutritional supplements not effective Rheumatoid Arthritis (RA) o Chronic, inflammatory, autoimmune disease of unknown cause Immune system attacks own cells o Usually arises between ages 40 and 50, but may occur at any age; affects three times as many women as men o Signs and symptoms include joint pain and swelling (usually bilateral), anemia, osteoporosis, muscle weakness, and cardiovascular problems o RA begins with inflammation of synovial membrane (synovitis) of affected joint o Inflammatory blood cells migrate to joint, release inflammatory chemicals that destroy tissues o Synovial fluid accumulates, causing joint swelling o Inflamed synovial membrane thickens into abnormal pannus tissue that clings to articular cartilage o Pannus erodes cartilage, scar tissue forms and connects articulating bone ends (ankylosis) o Treatment includes steroidal and nonsteroidal antiinflammatory drugs to decrease pain and inflammation o Disruption of destruction of joint by immune system Immune suppressants slow autoimmune reaction Some agents target tumor necrosis factor to block action of inflammatory chemicals o Can replace joint with prosthesis Gouty Arthritis o Deposition of uric acid crystals in joints and soft tissues, followed by inflammation o More common in men o Typically affects joint at base of great toe o In untreated gouty arthritis, bone ends fuse and immobilize joint o Treatment: drugs, plenty of water, avoidance of alcohol and foods high in purines, such as liver, kidneys, and sardines Lyme Disease o Caused by bacteria transmitted by tick bites o Symptoms: skin rash, flulike symptoms, and foggy thinking o May lead to joint pain and arthritis o Treatment Long course of antibiotics Joint Replacement Knee and hip replacements most common o Others possible Usually done due to severe osteoarthritis damage or a fracture o Fracture of femoral neck from a fall (blood cut off to femoral head) Bad end of bone ground down to fit prosthetic o Precision not too important because bone will grow to fit prosthetic, just as if repairing a fracture o Prosthetics usually titanium, plastic, or a combination of both
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