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11/07/12 Articulations BIOL241 – “Lecture 8” Overview • • • • • • • • Joint classifications: structural and functional Types of joints by functional classification Synovial joint detail Movements at synovial joints Classification of synovial joints by shape Examples of joints Injuries Arthritis Articulations • Body movement occurs at joints (articulations) where 2 bones connect • Weakest parts of the skeleton • Articulation – site where two or more bones meet • Functions of joints – Give the skeleton mobility – Hold the skeleton together 1 11/07/12 Joint Structure • Determines direction and distance of movement (range of motion) • Joint strength decreases as mobility increases Classification of Joints: Structural • Structural classification focuses on the material binding bones together and whether or not a joint cavity is present • The three structural classifications are: – Fibrous – Cartilaginous – Synovial Structural Classification Table 9–2 2 11/07/12 Structural Classifica3ons • • • • Bony (fused) Fibrous (collagen fibers) Car3laginous (car3lage) Synovial (synovial fluid) Classifica3on of Joints: Func3onal • Func3onal classifica3on is based on the amount of movement allowed by the joint • The three func3onal classes of joints are: – Synarthroses – immovable – Amphiarthroses – slightly movable – Diarthroses – freely movable Func3onal Classifica3on Table 9–1 3 11/07/12 Synarthroses • • • • • • Also called immovable joints Are very strong Edges of bones may touch or interlock Fibrous, bony, or car3laginous connec3ons May fuse over 3me Four types: – Suture – Gomphosis – Synchondrosis – Synostosis Synarthroses 1 of 2 • Suture – Bones are interlocked – Bound by dense fibrous connec3ve 3ssue – Found only in skull • Gomphosis – Fibrous connec3on (periodontal ligament) – Binds teeth to sockets Synarthrosis: Suture Figure 8.1a 4 11/07/12 Synarthroses 2 of 2 • Synchondrosis – A rigid car3laginous bridge between 2 bones: • epiphyseal car3lage of long bones • between vertebrosternal ribs and sternum • Synostosis – Fused bones, immovable: • metopic suture of skull • epiphyseal lines of long bones Synarthrosis: Synchondroses Figure 8.2a, b Amphiarthroses • Also called slightly moveable joints • Can be fibrous or car3laginous connec3ons Func3onally: • More moveable than synarthrosis • Stronger than freely movable joint • Types: – Syndesmosis – Symphysis 5 11/07/12 2 Types of Amphiarthroses • Syndesmosis: – bones connected by ligaments – e.g. between 3bia and fibula • Symphysis: – bones separated by fibrocar3lage – Examples? Amphiarthrosis (Fibrous) : Syndesmoses Figure 8.1b Amphiarthrosis (Car3laginous): Symphyses Figure 8.2c 6 11/07/12 Diarthroses Synovial joints Also called freely moveable joints At ends of long bones Found within ar3cular capsules (con3nuous with periosteum) lined with synovial membrane and filled with fluid • Include all limb joints and many others • Subdivided by the type of mo3on each can undergo • • • • Synovial Joints: General Structure • Synovial joints all have the following – Ar3cular car3lage – Joint (synovial) cavity – Ar3cular capsule – Synovial fluid – Reinforcing ligaments Synovial Joints: General Structure Figure 8.3a, b 7 11/07/12 Synovial membrane • Has incomplete epithelium • Areolar 3ssue underneath has rich blood supply • Creates synovial fluid and proteoglycans (from fibroblasts) to make it viscous • No blood supply enters the joint itself Fric3on Reduc3on Ar2cular car2lage: pads ar3cula3ng surfaces within ar3cular capsules to prevent bones from touching • Synovial fluid lubricates the smooth surfaces, con3ans proteoglycans secreted by fibroblasts (from where?) Func9ons: • 1. Lubrica3on 2. Shock absorp3on 3. Nutrient distribu3on – from areloalar 3ssue of synovial membrane to the ar3cular car3lage and fibrocar3lage pads Synovial Joints: Fric3on-‐Reducing Structures Figure 8.4 8 11/07/12 Synovial Joints: Stability • Stabilizing Factors -‐ prevent injury by limi3ng range of mo3on: – Ar3cular surfaces – shape determines what movements are possible – Ligaments – unite bones and prevent excessive or undesirable mo3on – Muscle tendons across joints ac3ng as stabilizing factors, are kept 3ght at all 3mes by muscle tone Accessory structures Part 1 • Car3lages: Cushion the joint – Ar3cular hyaline car3lage – fibrocar3lage meniscus (ar9cular disc) • Bursa: Cushion areas where ligaments, muscles, skin, tendons, or bones rub together – flabened, fibrous sacs lined with synovial membranes and containing synovial fluid – Tendon sheath: elongated bursa that wraps completely around a tendon Accessory structures Part 2 • Fat Pads: Protect ar3cular car3lages – Superficial (overlying) to the joint capsule • Accessory Ligaments: Support, strengthen joints • Tendons: Abach to muscles around joint to help support it 9 11/07/12 Synovial Joints: Movement • The two muscle abachments across a joint are: – Origin – abachment to the immovable bone – Inser3on – abachment to the movable bone • Described as movement along transverse (horizontal), frontal, or sagibal planes Basic types of dynamic mo3on • Linear mo3on (gliding) • Angular mo3on • Rota3on Linear Mo3on • One flat bone surface glides or slips over another similar surface • Examples – intercarpal and intertarsal joints, and between the flat ar3cular processes of the vertebrae Pencil maintains ver3cal orienta3on, but changes posi3on Figure 9–2a, b 10 11/07/12 Angular Mo3on • Pencil maintains posi3on, but changes orienta3on – Tip stays fixed; pencil does not rotate • Many examples Figure 9–2c Angular Mo3on • Flexion — bending movement that decreases the angle of the joint • Extension — reverse of flexion; joint angle is increased • Dorsiflexion and plantar flexion — up and down movement of the foot • Abduc3on — movement away from the midline • Adduc3on — movement toward the midline • Circumduc3on — movement describes a cone in space Angular Mo3on: Circumduc3on • Angular mo3on in a circle – Again, 3p does not rotate Figure 9–2d 11 11/07/12 Rota3on • NOT angular • Pencil maintains posi3on and orienta3on, but spins • Example – shaking your head Figure 9–2e Synovial Joints: Range of Mo3on • • • • Nonaxial – slipping movements only Monaxial/Uniaxial – movement in one plane Biaxial – movement in two planes Triaxial – movement in or around all three planes Types of Movements at Synovial Joints • Terms describe: – plane or direc3on of mo3on – rela3onship between structures • In the anatomical posi3on, all joints except one are at full extension 12 11/07/12 Gliding Movement Figure 8.5a Flexion/Extension • Angular mo3on in the Anterior–posterior plane • Flexion reduces angle between elements • Extension increases angle between elements Angular Movement – F/E Figure 8.5b 13 11/07/12 Hyperextension • Angular mo3on • Extension past anatomical posi3on Angular Movement -‐ Hyperextension Figure 8.5c, d Dorsiflexion and Plantar Flexion • Dorsiflexion: – flexion at ankle (liging toes) – Is “true flexion” • Plantar flexion: – extension at ankle (poin3ng toes) 14 11/07/12 Abduc3on and Adduc3on • Both are Angular mo3on in the Frontal plane • Abduc3on moves away from longitudinal axis • Adduc3on moves toward longitudinal axis Angular Movements -‐ Ab/Ad/Circum Figure 8.5e, f Circumduc3on • Angular mo3on in a circle without rota3on 15 11/07/12 Rota3on • The turning of a bone around its own long axis • Leg or right rota3on • Medial rota3on (inward rota9on): – rotates toward axis • Lateral rota3on (outward rota9on): – rotates away from axis • Examples – Between first two vertebrae – Hip and shoulder joints Figure 8.5g Special Movements • • • • • Supina3on and prona3on Inversion and eversion Protrac3on and retrac3on Eleva3on and depression Opposi3on Special Movements Figure 8.6a 16 11/07/12 Special Movements Figure 8.6b Special Movements Figure 8.6c Special Movements Figure 8.6d 17 11/07/12 Special Movements Figure 8.6e Lateral Flexion • Bends vertebral column from side to side Figure 9–5f MOVIE • Angular mo3ons 18 11/07/12 Classifica3on of Synovial Joints by Shape • • • • • • Gliding/Plane Hinge Pivot Ellipsoidal Saddle Ball-‐and-‐socket Gliding Joints • • • • Flabened or slightly curved faces Limited mo3on (only examples of nonaxial) Also called linear mo3on 2 surfaces slide past each other: – between carpal or tarsal bones Figure 9–6 (1 of 6) 19 11/07/12 Hinge Joints • Cylindrical projec3ons of one bone fits into a trough-‐shaped surface on another • Angular mo3on in a single plane (monaxial) • Flexion/extension only • Elbow, knee Figure 9–6 (2 of 6) Pivot Joints • Rounded end of one bone protrudes into a “sleeve,” or ring, composed of bone (and possibly ligaments) of another • Rota3on only (monaxial) • Shaking your head Figure 9–6 (3 of 6) Ellipsoidal Joints • Oval ar3cular face within a depression • Mo3on in 2 planes (biaxial) • Some wrist joints (e.g. radiocarpal) Figure 9–6 (4 of 6) 20 11/07/12 Saddle Joints • 2 concave faces, straddled (biaxial) • Thumb (carpometacarpal) Figure 9–6 (5 of 6) Ball-‐and-‐Socket Joints • A spherical or hemispherical ar3cular face head of one bone ar3culates with a cuplike socket of another (triaxial) • Shoulder, hip Figure 9–6 (6 of 6) MOVIE • Types of synovial joint mo3on 21 11/07/12 Specific joint examples Vertebrae, shoulder, elbow, hip, knee IMPORTANT • You DO NOT need to know the names of specific ligaments in the examples that follow. Only learn the general concepts about these joints (and the terms listed in blue). • You DO need to know what type of joint is found at any site in the body Intervertebral Ar3cula3ons Figure 9–7 22 11/07/12 Intervertebral Ar3cula3ons • C2 to L5 spinal vertebrae ar3culate in two places: – at inferior and superior ar3cular processes • gliding synovial joints – between adjacent vertebral bodies • symphyseal joints (symphysis = fibroca3lage pad) • The atlas and axis have a pivot joint (monaxial synovial) Intervertebral Discs • Intervertebral discs: – pads of fibrocar3lage that separate vertebral bodies • Slipped (bulging) disc: – bulge in outer anulus fibrosus of disc – invades vertebral canal, may press on nerves or cord • Herniated disc: – Inner, gela3nous nucleus pulposus breaks through anulus fibrosus – presses on spinal cord or nerves Damage to Intervertebral Discs Figure 9–8 23 11/07/12 Movements of the Vertebral Column • Flexion/Extension – bends anteriorly and posteriorly – Caused by small gliding movements of adjacent vertebrae • Lateral flexion: – bends laterally • Rota3on Temporomandibular Joint (TMJ) • Mandibular condyle ar3culate with the temporal bone • Two types of movement – Hinge – depression and eleva3on of mandible – Side to side – (lateral excursion) grinding of teeth Temporomandibular Joint Figure 8.13a, b 24 11/07/12 Ac3vity • Get in small groups • Compare and contrast the shoulder, hip, and knee joints on the basis of: – Range of mo3on – Stability/Protec3on – Injury frequency The Shoulder Joint Figure 9–9a The Shoulder Joint • Also called the glenohumeral joint: • Ball-‐and-‐socket triaxial diarthrosis in which stability is sacrificed to obtain greater freedom of movement • Head of humerus ar3culates with the glenoid fossa of the scapula • Allows more mo3on than any other joint • Is the least stable • Supported by skeletal muscles, tendons, ligaments 25 11/07/12 Shoulder Stability • Weak stability is maintained by: – Thin, loose joint capsule – Four ligaments – coracohumeral, and three glenohumeral – Tendon of the long head of biceps, which travels through the intertubercular groove and secures the humerus to the glenoid cavity – Rotator cuff (four tendons) that encircles the shoulder joint and blends with the ar3cular capsule Shoulder Stability Figure 8.11a Socket of the Shoulder Joint • Glenoid labrum: – deepens socket of glenoid cavity – fibrocar3lage lining – extends past the bone 26 11/07/12 Processes of the Shoulder Joint • Acromion (clavicle) and coracoid process (scapula): – project laterally, superior to the humerus – help stabilize the joint • Shoulder Separa3on – Par3al or complete disloca3on of Acromioclavicular joint Shoulder Muscles (FYI) • Also called rotator cuff: – supraspinatus – infraspinatus – subscapularis – teres minor The Hip Joint Figure 9–11a 27 11/07/12 Hip (Coxal) Joint • Ball-‐and-‐socket triaxial diarthrosis • Head of the femur ar3culates with the acetabulum • Socket of acetabulum is extended (made larger) by fibrocar3lage acetabular labrum • Good range of mo3on, but limited by the deep socket and strong ligaments • Stronger than shoulder, but more limited range of mo3on Hip Stability Acetabular labrum Iliofemoral ligament Pubofemoral ligament Ischiofemoral ligament • Ligamentum teres • • • • Figure 8.12a Hip Stability Figure 8.12c, d 28 11/07/12 The Knee Joint Figure 9–12a, b The Knee Joint Figure 9–12c, d The Knee Joint • • • • A complicated hinge joint Largest and most complex joint of the body Allows flexion, extension, and limited rota3on Three joints in one surrounded by a single joint cavity – Femoropatellar joint – Lateral and medial 3biofemoral joints (at medial and lateral condyles) • Transfers weight from femur to 3bia 29 11/07/12 Menisci of the Knee • Medial and lateral menisci: – fibrocar3lage pads – one at each femur–3bia ar3cula3on – cushion and stabilize joint – give lateral support • Standing with legs straight “locks” knees by jamming lateral meniscus between 3bia and femur which may interrupt venous return from lower leg FYI: 7 Ligaments of the Knee Joint • Patellar ligament (anterior) • 2 popliteal ligaments (posterior) • Anterior and posterior cruciate ligaments (inside joint capsule) • Tibial collateral ligament (medial) • Fibular collateral ligament (lateral) Knee Ligaments and Tendons – Anterior surface • Tendon of the quadriceps femoris muscle • Patellar ligament • Lateral and medial patellar re3nacula • Fibular and 3bial collateral ligaments Figure 8.8c 30 11/07/12 Knee – Interior Suppor3ng Structures • All inside the joint capsule: – Anterior cruciate ligament – Posterior cruciate ligament – Medial meniscus (semilunar car3lage) – Lateral meniscus Synovial Joints: Knee – Interior Suppor3ng Structures Figure 8.8b Knee – Posterior Superficial View • Adductor magnus tendon • Ar3cular capsule • Oblique popliteal ligament • Arcuate popliteal ligament • Semimembranosus tendon Figure 8.8e 31 11/07/12 The Elbow Joint • A stable hinge joint that allows flexion/ extension only • Ar3cula3ons between humerus -‐ radius, humerus – ulna • Biceps brachii muscle: – abached to radial tuberosity – controls elbow mo3on Ar3cula3ons of the Elbow • Humeroulnar joint: – larger ar3cula3on – trochlea of humerus and trochlear notch of ulna – limited movement • Humeroradial joint: – smaller ar3cula3on – capitulum of humerus and head of radius Synovial Joints: Elbow • Annular ligament • Ulnar collateral ligament • Radial collateral ligament Figure 8.10a 32 11/07/12 Synovial Joints: Elbow Figure 8.10b Elbow Figure 9–10 Injuries: Sprains and Strains Sprain: ligaments with torn collagen fibers – Par3ally torn ligaments slowly repair themselves – Completely torn ligaments require prompt surgical repair Strain: Muscles with torn fibers, also called “pulling a muscle” 33 11/07/12 Injuries: disloca3ons • Disloca3on (luxa3on): – ar3cula3ng surfaces forced out of posi3on – damages ar3cular car3lage, ligaments (sprains), joint capsule • Subluxa3on: – a par3al disloca3on Car3lage Injuries • The snap and pop of overstressed car3lage • Common aerobics injury • Repaired with arthroscopic surgery (ques3onable effec3veness Inflammatory and Degenera3ve Condi3ons • Bursi3s – An inflamma3on of a bursa, usually caused by a blow or fric3on – Symptoms are pain and swelling – Treated with an3-‐inflammatory drugs; excessive fluid may be aspirated • Tendoni3s – Inflamma3on of tendon sheaths (which are enlarged bursa) typically caused by overuse – Symptoms and treatment are similar to bursi3s 34 11/07/12 Arthri3s • All forms of rheuma3sm that damage ar3cular car3lages of synovial joints • More than 100 different types of inflammatory or degenera3ve diseases that damage the joints • Most widespread crippling disease in the U.S. • Symptoms – pain, s3ffness, and swelling of a joint Osteoarthri3s • Caused by wear and tear of joint surfaces, or gene3c factors affec3ng collagen forma3on • Affects women more than men • 85% of all Americans develop OA • Generally in people over age 60 • The exposed bone ends thicken, enlarge, form bone spurs, and restrict movement • Joints most affected are the cervical and lumbar spine, fingers, knuckles, knees, and hips • Treatments include glucosamine sulfate and CSPG to decreases pain and inflamma3on Rheumatoid Arthri3s • Chronic, inflammatory, autoimmune disease of unknown cause I • Involves the immune system • Usually arises between the ages of 40 to 50, but may occur at any age • Signs and symptoms include joint tenderness, anemia, osteoporosis, muscle atrophy, and cardiovascular problems – The course of RA is marked with exacerba3ons and remissions • Treatments include Enbrel, Remicade, Humira, methotreaxate 35 11/07/12 Developmental Aspects of Joints • By embryonic week 8, synovial joints resemble adult joints • Few problems occur un3l late middle age • Advancing years take their toll on joints: – Ligaments and tendons shorten and weaken – Intervertebral discs become more likely to herniate – Most people in their 70s have some degree of OA Summary • • • • • • • • Joint classifica3ons: structural and func3onal Types of joints by func3onal classifica3on Synovial joint detail Movements at synovial joints Classifica3on of synovial joints by shape Examples of joints Injuries Arthri3s 36