Articulations PDF

Chapter 9 Articulations Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Joints Bones are too rigid to bend – Meet at joints called articulations – Dif...

Chapter 9 Articulations Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Joints Bones are too rigid to bend – Meet at joints called articulations – Different joints with different shapes and supporting structures – Different type and range of movement Joint (articulation) – Place of contact between bones, bone and cartilage, or bones and teeth – Bones said to articulate at a joint – Arthrology, scientific study of joints – arthron - joints – Classified by structural characteristics and range of mobility – Names of joints are derived from the bones that make them up Radioulnar joint is between Radius and Ulna 1  Classification of Joints Classified by structural characteristics and range of mobility 1. Structurally based on whether a space exists (Joint cavity) between the articulating bones and the type of connective tissue that binds the articulating surfaces of the bones Fibrous, Cartilaginous, and Synovial joints 2. Based on extent of mobility Synarthrosis, Amphiarthrosis, and Diarthrosis – Motion ranges from no movement to extensive movement – Structure of each joint determines mobility and stability – Inverse relationship between mobility and stability 2  Fibrous Joints Characteristics of fibrous joints 1. Connected by dense regular connective tissue 2. Have no joint cavity Peg in a socket 3. Synarthrosis or Amphiathrosis Become ossified in adults – Synostoses 3  Cartilaginous Joints: Sympheses Properties of cartilaginous joints 1. Lack a joint cavity 2. Amphiathroses 3. Have cartilage between articulating bones Either hyaline or fibrocartilage Shock absorbers, resist compression and tension stress 4  Cartilaginous Joints: Synchondroses 1. 1st Sternocostal joint united firmly to manubrium provides stability to the rib cage 2. Costochondral joints Costochondritis - Inflammation of the costochondral joints 3. Epiphyseal plate Some synchondroses ossify over time. 5 Name the joint and decide the structural and functional category. 1. Parietal bone and occipital bones Lambdoid Suture Fibrous/Suture Synathrosis 2. True ribs and costal cartilage Costochondral Cartilaginous/Synchondrosis Synathrosis 3. Between vertebral bodies Intervertebral Cartilaginous / Symphysis Amphiathrosis 6  Synovial Joints Synovial joints – Include most joints in the body – Bones separated by a space, the joint cavity – All diarthroses – All with these basic features 1. Articular capsule – Strengthens joints to prevent bones being pulled apart – Two layers 2. Articular cartilage – lacks perichondrium – reduces friction during movement – acts as a cushion to absorb joint compression – prevents damage to articulating ends of bones 3. Joint cavity – Space permitting separation of articulating bones – Synovial membrane secreting synovial fluid – viscous, oily substance – secretions from synovial membrane cells and filtrate from plasma – Three functions of synovial fluid: 1. lubricates articular cartilage 2. acts as a shock absorber 3. nourishes and removes wastes from articular chondrocytes 7  Synovial Joints 4. Sensory nerves and blood vessels – Blood vessels – Innervate and supply articular capsule and ligaments – Proprioceptors - a sensory receptor which detect stretch and movement of a joint.. – Nociceptors - a sensory neuron that detects to damaging or potentially damaging stimuli 5. Ligaments – Stabilize, strengthen, and reinforce most synovial joints – Extrinsic ligaments – Intrinsic ligaments – capsular Tendons – Not part of the synovial joint itself – May limit the range of movement Bursa – Fibrous sacs or tendon sheaths – Connected to the joint cavity or separate – Found where bones, ligaments, muscles, skin, or tendons rub together Fat pad 8  Clinical View: Arthritis group of inflammatory or degenerative diseases of the joints symptoms of joint swelling, pain, and stiffness Gouty arthritis typically seen in middle-aged or older males due to increased levels of uric acid begins with attack on single joint  sweeling, pain, stiffness, etc. Osteoarthritis degenerative joint condition seen in older individuals due to gradual wearing down of articular cartilage fingers, knuckles, hips, knees, and shoulders most affected stiffness and pain Rheumatoid arthritis seen in younger to middle-aged adults, often women autoimmune disorder starts with synovial membrane inflammation the inflamed synovial membrane thickens; eventually, the articular cartilage and, often, the underlying bone become eroded. Scar tissue later forms and ossifies, and bone ends fuse together—a process called ankyloses.  Classification of Synovial Joints Classified by shapes of surfaces and movement allowed – Uniaxial joint – Biaxial joint – Multi-axial joint Joints (diathroses), from least to most mobile: – Plane joints – Hinge joints – Pivot joints – Condylar joints – Saddle joints – Ball-and-socket joints 9  Classification of Synovial Joints Carpal Plane joint bones – Simplest synovial articulation – Least mobile type of diarthrosis Triquetrum Plane joint – Uniaxial joint Trapezium Hamate bone (uniaxial) MP joint – Limited side-to-side movement in a single plane First (”knuckle”) metacarpal – Articular surfaces flat bone IP joints – E.g., intercarpal and intertarsal joints Phalanges Condylar joint Metacarpal bone – Biaxial joint, moving in two planes Proximal phalanx – Oval, convex surface articulating with concave surface – E.g., metacarpophalangeal joints of fingers and thumb (knuckles) Saddle joint – Convex and concave surfaces resembling saddle shape – Biaxial Saddle joint (biaxial) – Greater range of movement than condylar or hinge joint – E.g., carpometacarpal joint of the thumb Condylar joint permits thumb to move toward other fingers (biaxial) 10  Classification of Synovial Joints Condylar joint Pivot joint (biaxial) Dens of axis – Bone with rounded surface fits into ring formed by Atlas ligament from another bone rotates on longitudinal axis Axis relative to second bone – Uniaxial joint – E.g., proximal radioulnar joint – E.g., dens of axis and anterior Uniaxial joint Biaxial joint arch of atlas Multiaxial joint Pivot joint (uniaxial) 11  Hinge joint – Formed by convex surface fitting into concave Hinge joint depression (uniaxial) – Movement confined to a single axis, so uniaxial – Like the hinge of a door Humerus – E.g., elbow joint, knee, and interphalangeal joints Radius Ulna Ball-and-socket joint (multiaxial) Ilium Ball-and-socket joint – Multiaxial joints, permitting movement in 3 planes – Spherical head of one bone fitting into cuplike socket – E.g., coxal and glenohumeral joints – Considered the most freely mobile type Head of femur 12 Fibrous Hinge Condylar Pivot Symphysis and Plane Plane Plane Plane (2-7) 13  Temporomandibular Joint Bones of the joint Ligaments of the TMJ Movements of the TMJ Depression/elevation Protraction/retraction Excursion Features of the TMJ – Only mobile joint in skull – Has loose articular capsule – Has articular disc of fibrocartilage – Has articular tubercle – Sphenomandibular ligmanet – Tempromandibular ligament 14 TMJ Disorders – TMJ subject to various disorders – Most common due to alteration in the ligaments securing the joint – Articular disc forced out of normal position – Clicking or popping heard as person opens or closes mouth – Possible pain in joint, paranasal sinuses, tympanic membrane, oral cavity, eyes, and teeth all structures innervated by trigeminal nerve https://www.youtube.com/watch?v=mB468Jh9aAY​ 15 16  Shoulder Joint 1. Sternoclavicular Joint – Saddle joint – Articular disc – Elevation, depression, circumduction possible – Stability provided by fibers and ligaments – Sternoclavicular ligament makes joint very stable and difficult to dislocate 17 Fractured clavicle Mechanism of injury 18  Shoulder Joint 2. Acromioclavicular Joint – Plane joint – Fibrocartilaginous articular disc – Works with sternoclavicular and glenohumeral joint – The capsule is weak and is strengthened by capsular ligaments both inferiorly and superiorly, which in turn are reinforced through attachments from the deltoid and trapezius – Acromioclavicular ligament – Coracoclavicular ligament 19  Shoulder Joint Shoulder separation – Dislocation of acromioclavicular joint – Dislocation - displacement – Often results from a hard blow to the joint – Tenderness and swelling in joint region – Pain when arm abducted more than 90 degrees – Acromion appearing prominent 20  Shoulder Joint 3. Glenohumeral Joint – Commonly referred to as the shoulder joint – Permits greatest range of motion of any joint in the body – Most unstable and most frequently dislocated Ligaments strengthening joint only minimally Most joint strength due to surrounding rotator cuff muscles – work as a group to hold head of humerus in glenoid cavity – tendons encircle joint and fuse with articular capsule – inferior portion lacking muscles – Fibrocartilaginous glenoid labrum – Loose articular capsule attached to humerus – Coracoacromial ligament – Coracohumeral ligament – Glenohumeral ligaments – Tendon of long head of biceps brachii – Abundant bursae 21 22  Dislocation of the Glenohumeral Joint Common due to joint instability – Usually occur when fully abducted humerus struck hard – Shoulder appears flattened and “squared-off” – Muscles pull it superiorly and medially – Humeral head anterior and inferior to glenohumeral joint capsule 23  Elbow Joint Hinge joint composed of two articulations: 1. humeroulnar joint Trochlea / Trochlear notch 2. humeroradial joint Capitulum / radial head Trochlea – Both enclosed within a single articular capsule Articular capsule Humerus Stability of the elbow joint Coronoid process – Very stable joint for several reasons: bony surfaces of humerus and ulna Radius interlocking well Thick articular capsule protects the Articular cartilage articulations Ulna multiple strong ligaments to help reinforce Olecranon articular capsule Trochlear notch – Very stable but not as mobile as some others (d) Right elbow, medial sagittal section 24  Ligaments of Elbow Joint Humerus Only Flexion and Extension allowed Lateral epicondyle Stress to the elbow joint Medial Articular capsule epicondyle – May be damaged from severe stress Radial collateral ligament Ulnar collateral – E.g., falling on an outstretched Anular ligament ligament hand with elbow joint partly flexed Tendon of biceps may break the ulna brachii (cut) – E.g., dislocations from stresses to Radius the elbow children and teenagers more Ulna prone to humeral epicondyle dislocations or fractures 25  Subluxation of the Head of the Radius – subluxation refers to incomplete dislocation contact altered between joint surfaces still in partial contact – doctor may maneuver radial head back into annular ligament 26 27  Saddle Plane Ball and socket Hinge Pivot Condylar Pivot plane Saddle Plane Condyle hinge 28  Coxal Joint Hip joint – Articulation between head of the femur and acetabulum of the os coxa Acetabular labrum – Acetabular labrum, fibrocartilaginous ring Articular capsule Acetabulum – More stable and less mobile than glenohumeral Ligament of Greater joint trochanter head of femur of femur Support of the hip joint – Secured by articular capsule, ligaments, and Retinacular fibers muscles – Articular capsule – Retinacular fibers ligamentous fibers of articular capsule – Ligament of the head of femur (c) Right hip, coronal section 29  Hip Joint: Intracapsular Spiraling ligaments The hip joint is very Iliofemoral ligament Ischiofemoral ligament Iliofemoral ligament stable Greater Greatertrochanter trochanter Movements possible Pubofemoral ligament at the hip joint include: Lesser Lesser – Flexion, extension, trochanter trochanter abduction, adduction, Ischial tuberosity rotation, circumduction Hip most stable in the (a) Right hip, anterior view (b) Right hip, posterior view extended position 30  Femoral Fracture Often incorrectly referred to as “fractured hip” Leg rotated laterally and appears shorter Intertrochanteric fractures – extracapsular fractures – usually in younger and middle aged individuals in response to trauma Subcapital fractures – occur within hip articular capsule – usually occurs in elderly people with osteoporosis – may result in tearing of retinacular arteries avascular necrosis in the region 31  Knee Joint Largest and most complex diarthrosis Primarily a hinge joint Composed of two separate articulations : 1) tibiofemoral joint 2) patellofemoral joint Structures of the knee joint No single unified capsule or joint cavity Articular capsule – – Anterior surface is reinforced by the quadriceps tendon Patellar ligament hyperadduction Fibular collateral ligament – Prevent hyperadduction hyperabduction Tibial collateral ligament – Prevents hyperabduction 32  Knee Joint Cruciate ligaments 1. Anterior cruciate ligament (ACL) extends from posterior femur to anterior tibia prevents tibia moving too far anteriorly on the femur Prevent hyperextension of the knee 2. Posterior cruciate ligament (PCL) runs from anteroinferior femur to posterior tibia prevents posterior displacement of tibia Prevents hyperflexion Medial meniscus and lateral meniscus c-shaped fibrocartilage pads positioned on condyles of tibia act as cushioning between articular surfaces change shape to conform to articulating surfaces 33  Knee Ligament and Cartilage Injuries 1. Tibial collateral ligament injury - common 2. ACL injury – very common – injured when leg hyperextended 3. Menisci injury – may occur due to blows at the knee or overuse 4. Unhappy triad – triple injury of tibial collateral ligament, medial meniscus, and ACL – occurs when football player gets lateral blow to knee – leg abducted and laterally rotated Anterior view of right knee 34 35  Plantar flexion Talocrural (Ankle) Joint Dorsiflexion Fibula Tibia Highly modified hinge joint Posterior tibiofibular Anterior tibiofibular ligament Includes two articulations within one joint ligament Talus capsule Lateral Medial and lateral malleoli of tibia and ligament fibula – form extensive medial and lateral margins Calcaneus Metatarsal V – prevent talus from sliding (a) Right foot, lateral view Articular capsule – covers distal tibia, medial malleolus, Tibia lateral malleolus, and talus Deltoid ligament Deltoid ligament Navicular bone Talus Lateral ligament Metatarsal I Tibiofibular ligaments Calcaneus (b) Right foot, medial view 36  Ankle Sprains and Pott Fractures Sprain stretching or tearing of lateral ligaments due to overinversion occurring without fracture or joint dislocation localized swelling and tenderness anteroinferior to lateral malleolus overeversion sprains are rare due to strong deltoid ligament Pott fracture occurs if overeversion does occur medial malleolus of tibia pulled off fibula fracturing as well deltoid ligament remaining intact 37 Plane Ball and socket Cartilaginous Plane Hinge Plane Syndesmosis Hinge Plane Plane Condyle 38 hinge