Joints Slides by Vince Austin and W. Rose. figures from Marieb & Hoehn 7 th and 8 th eds. Portions copyright Pearson Education

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Joints (Articulations)  Weakest parts of the skeleton  Articulation – site where two or more bones meet  Functions of joints  Give the skeleton mobility  Hold the skeleton together

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Joints: Functional  Functional classification is based on the amount of movement allowed by the joint  The three functional classes of joints are:  Synarthroses – immovable  Amphiarthroses – slightly movable  Diarthroses – freely movable

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints  The bones are joined by fibrous tissues  There is no joint cavity  Most are immovable  There are three types – sutures, syndesmoses, and gomphoses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Sutures  Occur between the bones of the skull  Comprised of interlocking junctions completely filled with connective tissue fibers  Bind bones tightly together, but allow for growth during youth  In middle age, skull bones fuse and are called synostoses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Sutures Figure 8.1a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Syndesmoses  Bones are connected by a fibrous tissue ligament  Movement varies from immovable to slightly variable  Examples include the connection between the tibia and fibula, and the radius and ulna

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Syndesmoses Figure 8.1b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Gomphoses  The peg-in-socket fibrous joint between a tooth and its alveolar socket  The fibrous connection is the periodontal ligament

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints  Articulating bones are united by cartilage  Lack a joint cavity  Two types – synchondroses and symphyses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Synchondroses  A bar or plate of hyaline cartilage unites the bones  All synchondroses are synarthrotic  Examples include:  Epiphyseal plates of children  Joint between the costal cartilage of the first rib and the sternum

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Synchondroses Figure 8.2a, b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Symphyses  Hyaline cartilage covers the articulating surface of the bone and is fused to an intervening pad of fibrocartilage  Amphiarthrotic joints designed for strength and flexibility  Examples include intervertebral joints and the pubic symphysis of the pelvis

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Symphyses Figure 8.2c

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints  Those joints in which the articulating bones are separated by a fluid-containing joint cavity  All are freely movable diarthroses  Examples – all limb joints, and most joints of the body

Joints: Structural Classification FibrousCartilaginousSynovial SuturesSyndesmosesGomphosesSynchondrosesSymphyses Hyaline cartilage on joint surfaces Most sophisticated structure Synarthrotic Cranial Synarthrotic or amphiarhtrotic Tibiofibular, radioulnar Synarthrotic Teeth All are synarthrotic rib1-manubrium; epiphyseal plates All are amphiarthrotic Pubic, intervertebral All are diarthrotic Most joints in body Joints: Functional Classification SynarthrosesAmphiarthrosesDiarthroses no movementslight movementfree movement Most fibrous joints (except some syndesmoses) All synchondroses All symphyses Some syndesmoses All synovial joints

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: General Structure  Synovial joints all have the following  Articular cartilage  Joint (synovial) cavity  Articular capsule  Synovial fluid  Reinforcing ligaments

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: General Structure Figure 8.3a, b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 8.2.1

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: Friction-Reducing Structures  Bursae – flattened, fibrous sacs lined with synovial membranes and containing synovial fluid  Common where ligaments, muscles, skin, tendons, or bones rub together  Tendon sheath – elongated bursa that wraps completely around a tendon

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: Friction-Reducing Structures Figure 8.4

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: Stability  Stability is determined by:  Articular surfaces – shape determines what movements are possible  Ligaments – unite bones and prevent excessive or undesirable motion

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: Stability  Muscle tone is accomplished by:  Muscle tendons across joints acting as stabilizing factors  Tendons that are kept tight at all times by muscle tone

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: Movement  The two muscle attachments across a joint are:  Origin – attachment to the immovable bone  Insertion – attachment to the movable bone  Described as movement along transverse, frontal, or sagittal planes

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Gliding Movements  One flat bone surface glides or slips over another similar surface  Examples – intercarpal and intertarsal joints, and between the flat articular processes of the vertebrae

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Angular Movement  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

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Angular Movement  Abduction — movement away from the midline  Adduction — movement toward the midline  Circumduction — movement describes a cone in space

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Gliding Movement Figure 8.5a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Angular Movement Figure 8.5b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Angular Movement Figure 8.5c, d

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Angular Movement Figure 8.5e, f

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Rotation  The turning of a bone around its own long axis  Examples  Between first two vertebrae  Hip and shoulder joints Figure 8.5g

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Special Movements  Supination and pronation  Inversion and eversion  Protraction and retraction  Elevation and depression  Opposition

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Special Movements Figure 8.6a

Pronation and Supination at the Ankle At ankle:Pronation  Eversion* (see next slide) Supination  Inversion* Normal Gait: Heel strikes on lateral portion with ankle slightly inverted and plantar flexed. This is the supinated position. Then pronation occurs as rest of foot comes down: ankle moves into eversion (weight shifts medially) and dorsiflexion. It was long thought that overpronation or underpronation (above or below average eversionwas a cause of foot, ankle, knee injuries. Shoe companies marketed “motion control” shoes. However there is evidence that over/underpronators are not more injury prone, and that moderate overpronators may have fewer injuries than “neutral” runners.there is evidence *Supination is inversion plus plantarflexion and adduction: a triplanar motion involving the foot moving down and towards the center of the body. Pronation is eversion plus dorsiflexion and abduction: a triplanar motion of the subtalar joint involving the foot moving up and away from the center of the body.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Special Movements Figure 8.6b  supination  pronation

Right foot, posterior view

Overpronation.

Bottom of a right shoe. Red areas are worn down. Some evidence suggests picking shoes to match the runner’s ankle motion leads to more, not fewer, injuries. (A, B) Image: Excessive medial wear Excessive lateral wear Evenly distributed wear

Varus and Valgus Describe alignment of two segments in the frontal (coronal) plane. Varus alignment: distal segment deviates medially relative to proximal segment. Valgus alignment: distal segment deviates laterally relative to proximal segment. Varus, valgus often used to describe alignment at knee and ankle. Valgus at the knee: “knock-kneed” Varus at the knee: “bow-legged” Bunion: hallux valgus Proximal segment Distal seg. MedialLateral Varus Proximal segment Distal seg. MedialLateral Valgus Left Knee, Anterior View

Talocrural Joint Ankle Joint (talus to lower leg = crural region) Ankle sprain – most common joint injury Low ankle sprain: tear of ligaments “below the ankle” Inversion sprain – more common – damage to lateral ligaments (ant. & post. talofibular, calcaneofibular) Eversion – damage to medial (deltoid) ligament High ankle sprain: tear of ligaments “above the ankle” Tear of syndesmotic ligaments of distal tibiofibular joint (tibiofibular joints are syndesmotic, a subset of fibrous, and amphiarthrotic, i,.e. slightly movable.) High ankle sprain generally takes longer to heal.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Special Movements Figure 8.6c

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Special Movements Figure 8.6e