Joints PDF

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JOINTS lecture - Professor Tonya Penkrot...

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Joints 

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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)   

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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 Atlanto-occipital 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 

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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 

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Bony joint, or synostosis: 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, synarthrosis, 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, non-overlapping 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 

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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, amphiarthrosis 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

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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   

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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 fibroblast-like 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 ball-and-socket 2. Ligament number and location (limited role)

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The more ligaments, the stronger the joint 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 Warm-up 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 

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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  "double-jointed" 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 

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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 movements 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 

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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

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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  Ball-and-socket

Glenohumeral Joint 

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Ball-and-socket 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 Ball-and-socket 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  

Ball-and-socket 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)

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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 

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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 

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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

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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, anti-inflammatory drugs

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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 ("wear-and-tear") 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 to as crepitus, 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 anti-inflammatory 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, flu-like symptoms, and foggy thinking o May lead to joint pain and arthritis o Treatment

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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...