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Anatomy & Physiology I Lecture 7 Chapter 8: Joints Joints • Also called articulations – sites where two or more bones meet • Functions of joints – Give skeleton mobility – Hold skeleton together • Two classifications – Functional – Structural Functional Classification • Based on – Amount of movement joint allows • Three functional classifications: – Synarthroses—immovable joints – Amphiarthroses—slightly movable joints – Diarthroses—freely movable joints Structural Classification • Based on – Material binding bones together – Presence/absence of joint cavity • Three structural classifications: – Fibrous joints – Cartilaginous joints – Synovial joints Fibrous Joints • Bones joined by dense fibrous connective tissue • No joint cavity • Most synarthrotic (immovable) – Depends on length of connective tissue fibers • Three types: – Sutures – Syndesmoses – Gomphoses Figure 8.1a Fibrous joints. Suture Joint held together with very short, interconnecting fibers, and bone edges interlock. Found only in the skull. Suture line Dense fibrous connective tissue © 2013 Pearson Education, Inc. Figure 8.1b Fibrous joints. Syndesmosis Joint held together by a ligament. Fibrous tissue can vary in length, but is longer than in sutures. Fibula Tibia Ligament © 2013 Pearson Education, Inc. Figure 8.1c Fibrous joints. Gomphosis “Peg in socket” fibrous joint. Periodontal ligament holds tooth in socket. Socket of alveolar process Root of tooth Periodontal ligament © 2013 Pearson Education, Inc. Cartilaginous Joints • • • • Bones united by cartilage No joint cavity Not highly movable Two types: – Synchondroses – Symphyses Figure 8.2a Cartilaginous joints. Synchondroses Bones united by hyaline cartilage Epiphyseal plate (temporary hyaline cartilage joint) © 2013 Pearson Education, Inc. Sternum (manubrium) Joint between first rib and sternum (immovable) Figure 8.2b Cartilaginous joints. Symphyses Bones united by fibrocartilage Body of vertebra Fibrocartilaginous intervertebral disc (sandwiched between hyaline cartilage) © 2013 Pearson Education, Inc. Pubic symphysis Synovial Joints • Bones separated by fluid-filled joint cavity • All are diarthrotic (freely movable) • Include ~ all limb joints; most joints of body Synovial Joints: Six Distinguishing Features 1. Articular cartilage: hyaline cartilage – Prevents crushing of bone ends 2. Joint (synovial) cavity – Small, fluid-filled potential space Synovial Joints: Six Distinguishing Features 3. Articular (joint) capsule • Two layers – External Fibrous layer • Dense irregular connective tissue – Inner Synovial membrane • Loose connective tissue • Makes synovial fluid Synovial Joints: Six Distinguishing Features 4. Synovial fluid – Viscous, slippery filtrate of plasma and hyaluronic acid – Lubricates and nourishes articular cartilage – Contains phagocytic cells to remove microbes and debris Synovial Joints: Six Distinguishing Features 5. Different types of reinforcing ligaments – Capsular • Thickened part of fibrous layer – Extracapsular • Outside the capsule – Intracapsular • Deep to capsule; covered by synovial membrane Synovial Joints: Six Distinguishing Features 6. Nerves and blood vessels – Nerve fibers detect pain, monitor joint position and stretch – Capillary beds supply filtrate for synovial fluid Figure 8.3 General structure of a synovial joint. Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous layer Synovial membrane (secretes synovial fluid) Periosteum © 2013 Pearson Education, Inc. Articular capsule Other Features of Synovial Joints • Fatty pads – For cushioning between fibrous layer and synovial membrane or bone – hip and knee joints • Articular discs (menisci) – Fibrocartilage separates articular surfaces to improve "fit" of bone ends, stabilize joint, and reduce wear and tear – knee Other Features of Synovial Joints • Bursae – Sacs lined with synovial membrane • Contain synovial fluid – Reduce friction where ligaments, muscles, skin, tendons, or bones rub together • Tendon Sheaths – Elongated bursa wrapped completely around tendon subjected to friction Figure 8.4a Bursae and tendon sheaths. Acromion of scapula Subacromial bursa Joint cavity containing synovial fluid Fibrous layer of articular capsule Articular cartilage Tendon sheath Synovial membrane Tendon of long head of biceps brachii muscle Fibrous layer Humerus Frontal section through the right shoulder joint © 2013 Pearson Education, Inc. Figure 8.4b Bursae and tendon sheaths. Bursa rolls and lessens friction. Humerus head rolls medially as arm abducts. Humerus moving Enlargement of (a), showing how a bursa eliminates friction where a ligament (or other structure) would rubInc. against a bone © 2013 Pearson Education, Three Stabilizing Factors at Synovial Joints • Shapes of articular surfaces (minor role) • Ligament number and location (limited role) • Muscle tendons that cross joint (most important) – Muscle tone keeps tendons taut • Extremely important in reinforcing shoulder and knee joints and arches of the foot Need a Summary? • Refer to Table 8.2: – Joint names – Articulating bones – Structural classification – Functional classification – Movements allowed Synovial Joints: Movements Allowed • All muscles attach to bone or connective tissue at no fewer than two points – Origin—attachment to immovable bone – Insertion—attachment to movable bone • Muscle contraction causes insertion to move toward origin Synovial Joints: Range of Motion • • • • Nonaxial—slipping movements only Uniaxial—movement in one plane Biaxial—movement in two planes Multiaxial—movement in or around all three planes Three General Types of Movements at Synovial Joints 1. Gliding 2. Angular movements – Flexion, extension, hyperextension – Abduction, adduction – Circumduction 3. Rotation – Medial and lateral rotation Gliding Movements • One flat bone surface glides or slips over another similar surface • Examples: – Intercarpal joints – Intertarsal joints – Between articular processes of vertebrae Angular Movements • Increase or decrease angle between two bones • Movement along sagittal plane – Flexion—decreases the angle of the joint – Extension—increases the angle of the joint • Hyperextension—movement beyond the anatomical position Angular Movements • Movement along frontal plane – Abduction—movement away from the midline – Adduction—movement toward the midline • Circumduction – Involves flexion, abduction, extension, and adduction of limb – Limb describes cone in space Rotation • Turning of bone around its own long axis – Toward midline or away from it – Medial and lateral rotation • Examples: – Between C1 and C2 vertebrae – Rotation of humerus and femur Special Movements • • • • • • Supination and Pronation Dorsiflexion and Planter Flexion Inversion and Eversion Protraction and Retraction Elevation and Depression Opposition Lab Exercise • Practice and understand the meaning of these movements Types of Synovial Joints • Six types, based on shape of articular surfaces: – Plane – Hinge – Pivot – Condylar – Saddle – Ball-and-socket Figure 8.7a The shapes of the joint surfaces define the types of movements that can occur at a synovial joint; they also determine the classification of synovial joints into six structural types. Plane joint Metacarpals Nonaxial movement Flat articular surfaces Gliding Carpals Examples: Intercarpal joints, intertarsal joints, joints between vertebral articular surfaces © 2013 Pearson Education, Inc. Figure 8.7b The shapes of the joint surfaces define the types of movements that can occur at a synovial joint; they also determine the classification of synovial joints into six structural types. Hinge joint Humerus Ulna Uniaxial movement Medial/lateral axis Cylinder Trough Flexion and extension Examples: Elbow joints, interphalangeal joints © 2013 Pearson Education, Inc. Figure 8.7c The shapes of the joint surfaces define the types of movements that can occur at a synovial joint; they also determine the classification of synovial joints into six structural types. Pivot joint Uniaxial movement Vertical axis Ulna Radius Sleeve (bone and ligament) Axle (rounded bone) Rotation Examples: Proximal radioulnar joints, atlantoaxial joint © 2013 Pearson Education, Inc. Figure 8.7d The shapes of the joint surfaces define the types of movements that can occur at a synovial joint; they also determine the classification of synovial joints into six structural types. Condylar joint Medial/ lateral axis Phalanges Metacarpals Biaxial movement Anterior/ posterior axis Oval articular surfaces Flexion and extension Examples: Metacarpophalangeal (knuckle) joints, wrist joints © 2013 Pearson Education, Inc. Adduction and abduction Figure 8.7e The shapes of the joint surfaces define the types of movements that can occur at a synovial joint; they also determine the classification of synovial joints into six structural types. Biaxial movement Saddle joint Medial/ lateral axis Metacarpal Trapezium © 2013 Pearson Education, Inc. Articular surfaces are both concave and convex Anterior/ posterior axis Adduction and abduction Example: Carpometacarpal joints of the thumbs Flexion and extension Figure 8.7f The shapes of the joint surfaces define the types of movements that can occur at a synovial joint; they also determine the classification of synovial joints into six structural types. Ball-and-socket joint Cup (socket) Medial/lateral axis Multiaxial movement Anterior/posterior axis Vertical axis Scapula Spherical head (ball) Humerus Flexion and extension Examples: Shoulder joints and hip joints © 2013 Pearson Education, Inc. Adduction and abduction Rotation Knee Joint • Largest, most complex joint of body • Three joints surrounded by a single joint cavity – Femoropatellar joint • Plane joint • Allows gliding motion during knee flexion – Lateral and medial tibiofemoral joints • Femoral condyles with lateral and medial menisci of tibia • Allow flexion, extension, and some rotation when knee partly flexed Knee • At least 12 associated bursae • Capsule is reinforced by muscle tendons – quadriceps and semimembranosus tendons • Joint capsule is thin • Anteriorly, quadriceps tendon gives rise to three broad ligaments – Medial and lateral patellar retinacula – Patellar ligament Figure 8.8a The knee joint. Femur Articular capsule Posterior cruciate ligament Tendon of quadriceps femoris Suprapatellar bursa Patella Subcutaneous prepatellar bursa Synovial cavity Lateral meniscus Lateral meniscus Anterior cruciate ligament Infrapatellar fat pad Deep infrapateller bursa Tibia Patellar ligament Sagittal section through the right knee joint © 2013 Pearson Education, Inc. Figure 8.8b The knee joint. Anterior cruciate ligament Articular cartilage on medial tibial condyle Medial meniscus Anterior Articular cartilage on lateral tibial condyle Lateral meniscus Posterior cruciate ligament Superior view of the right tibia in the knee joint, showing the menisci and cruciate ligaments © 2013 Pearson Education, Inc. Figure 8.8c The knee joint. Quadriceps femoris muscle Tendon of quadriceps femoris muscle Patella Lateral patellar retinaculum Fibular collateral ligament Fibula Anterior view of right knee © 2013 Pearson Education, Inc. Medial patellar retinaculum Tibial collateral ligament Patellar ligament Tibia Ligaments Stabilizing Knee Joint • Capsular and extracapsular ligaments – Help prevent hyperextension of knee – Fibular and tibial collateral ligaments – Oblique popliteal ligament – Arcuate popliteal ligament Figure 8.8d The knee joint. Tendon of adductor magnus Medial head of gastrocnemius muscle Popliteus muscle (cut) Tibial collateral ligament Tendon of semimembranosus muscle Femur Articular capsule Oblique popliteal ligament Lateral head of gastrocnemius muscle Bursa Fibular collateral ligament Arcuate popliteal ligament Tibia Posterior view of the joint capsule, including ligaments © 2013 Pearson Education, Inc. Ligaments Stabilizing Knee Joint • Intracapsular ligaments – Prevent anterior-posterior displacement – Reside outside synovial cavity – Anterior cruciate ligament • Attaches to anterior tibia – Posterior cruciate ligament • Attaches to posterior tibia Figure 8.8e The knee joint. Lateral condyle of femur Lateral meniscus Posterior cruciate ligament Medial condyle Tibial collateral ligament Anterior cruciate ligament Tibia Medial meniscus Fibular collateral ligament Patellar ligament Fibula Patella Quadriceps tendon Anterior view of flexed knee, showing the cruciate ligaments (articular capsule removed, and quadriceps tendon cut and reflected distally) Shoulder (Glenohumeral) Joint • Ball-and-socket joint – Head of humerus with glenoid cavity of scapula • Most freely moving joint in body – Stability sacrificed Figure 8.10a The shoulder joint. Acromion of scapula Coracoacromial ligament Subacromial bursa Fibrous layer of articular capsule Synovial cavity of the glenoid cavity containing synovial fluid Articular cartilage Tendon sheath Tendon of long head of biceps brachii muscle Frontal section through right shoulder joint Synovial membrane Fibrous layer of articular capsule Humerus Shoulder Joint • Reinforcing ligaments – Primarily on anterior aspect – Coracohumeral ligament • Helps support weight of upper limb – Three glenohumeral ligaments • Weak and sometimes absent Figure 8.10c The shoulder joint. Acromion Coracoacromial ligament Subacromial bursa Coracohumeral ligament Greater tubercle of humerus Transverse humeral ligament Tendon sheath Tendon of long head of biceps brachii muscle Anterior view of right shoulder joint capsule © 2013 Pearson Education, Inc. Coracoid process Articular capsule reinforced by glenohumeral ligaments Subscapular bursa Tendon of the subscapularis muscle Scapula Figure 8.10d The shoulder joint. Acromion Coracoid process Articular capsule Glenoid cavity Glenoid labrum Tendon of long head of biceps brachii muscle Glenohumeral ligaments Tendon of the subscapularis muscle Scapula Posterior Anterior Lateral view of socket of right shoulder joint, © 2013 Pearson Education, Inc. humerus removed Elbow Joint • Articulation of radius and ulna with humerus • Hinge joint – Primarily trochlear notch of ulna with trochlea of humerus – Flexion and extension only Figure 8.11a The elbow joint. Articular capsule Synovial membrane Humerus Synovial cavity Articular cartilage Fat pad Tendon of triceps muscle Bursa Coronoid process Tendon of brachialis muscle Ulna Trochlea Articular cartilage of the trochlear notch Median sagittal section through right elbow (lateral view) © 2013 Pearson Education, Inc. Elbow Joint • Anular ligament – Surrounds head of radius • Two capsular ligaments restrict side-to-side movement – Ulnar collateral ligament – Radial collateral ligament Figure 8.11b The elbow joint. Humerus Anular ligament Radius Lateral epicondyle Articular capsule Radial collateral ligament Olecranon Ulna Lateral view of right elbow joint © 2013 Pearson Education, Inc. Figure 8.11d The elbow joint. Articular capsule Anular ligament Humerus Coronoid process Medial epicondyle Radius Ulnar collateral ligament Ulna Medial view of right elbow Hip (Coxal) Joint • Ball-and-socket joint • Head of the femur articulates with acetabulum • Good range of motion, but limited by the deep socket – Rim of fibrocartilage - Acetabular labrum • Enhances depth of socket so hip dislocations rare Figure 8.12a The hip joint. Articular cartilage Acetabular labrum Coxal (hip) bone Ligament of the head of the femur (ligamentum teres) Femur Synovial cavity Articular capsule Frontal section through the right hip joint © 2013 Pearson Education, Inc. Hip (Coxal) Joint • Reinforcing ligaments – Iliofemoral ligament – Pubofemoral ligament – Ischiofemoral ligament – Ligamentum teres Figure 8.12c The hip joint. Iliofemoral ligament Ischium Ischiofemoral ligament Greater trochanter of femur Posterior view of right hip joint, capsule in place © 2013 Pearson Education, Inc. Figure 8.12d The hip joint. Anterior inferior iliac spine Iliofemoral ligament Pubofemoral ligament Greater trochanter Anterior view of right hip joint, capsule in place © 2013 Pearson Education, Inc. Lab Exercise for today • Lab Exercise 13, not activities 3 and 4 – What to know? • Types of joints • Types of synovial joints and their movements • Structural and Functional Characteristics of: – – – – – – Intervetebral Sternocostal Elbow Knee Acromioclavicular and Shoulder Sacroiliac and Hip What else to know? • The major ligaments of the hip joints (in bold) • The major ligaments of the knee joint (in bold) • The major ligaments of the shoulder joint (in bold)