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JointsJointsArticulating your bodyArticulating your body
Joints (Articulations)Joints (Articulations) Weakest parts of the skeletonWeakest parts of the skeleton
Articulation – site where two or more Articulation – site where two or more bones meetbones meet
Functions of jointsFunctions of joints Give the skeleton mobilityGive the skeleton mobility Hold the skeleton togetherHold the skeleton together
Classification of Joints: Classification of Joints: StructuralStructural
Structural classification Structural classification focuses on the material between bones focuses on the material between bones Whether or not a joint cavity is presentWhether or not a joint cavity is present
The three structural classifications are:The three structural classifications are: FibrousFibrous Cartilaginous Cartilaginous Synovial Synovial
Classification of Joints: Classification of Joints: FunctionalFunctional
Functional classification is based on Functional classification is based on the amount of movement allowed by the amount of movement allowed by the jointthe joint
The three functional classes of joints The three functional classes of joints are:are: Synarthroses – immovable Synarthroses – immovable Amphiarthroses – slightly movable Amphiarthroses – slightly movable Diarthroses – freely movableDiarthroses – freely movable
Fibrous Structural JointsFibrous Structural Joints The bones are joined by fibrous The bones are joined by fibrous
tissuestissues There is no joint cavityThere is no joint cavity Most are immovableMost are immovable There are three types There are three types
SuturesSutures SyndesmosesSyndesmoses gomphosesgomphoses
SuturesSutures
Figure 8.1a
SuturesSutures Occur between the bones of the skullOccur between the bones of the skull Comprised of interlocking junctions Comprised of interlocking junctions
completely filled with connective completely filled with connective tissue fiberstissue fibers
Bind bones tightly together, but allow Bind bones tightly together, but allow for growth during youthfor growth during youth
In middle age, skull bones fuse and In middle age, skull bones fuse and are called synostosesare called synostoses
SyndesmosesSyndesmoses
Figure 8.1b
SyndesmosesSyndesmoses Bones are connected by a fibrous Bones are connected by a fibrous
tissue ligamenttissue ligament
Movement varies from immovable to Movement varies from immovable to slightly variableslightly variable
GomphosesGomphoses The peg-in-socket fibrous joint The peg-in-socket fibrous joint
between a tooth and its alveolar between a tooth and its alveolar socketsocket
The fibrous connection is the The fibrous connection is the periodontal ligamentperiodontal ligament
Cartilaginous JointsCartilaginous Joints Articulating bones are united by Articulating bones are united by
cartilagecartilage
Lack a joint cavityLack a joint cavity
Two types – synchondroses and Two types – synchondroses and symphysessymphyses
SynchondrosesSynchondroses
Figure 8.2a, b
SynchondrosesSynchondroses A bar or plate of hyaline cartilage A bar or plate of hyaline cartilage
unites the bonesunites the bones
All synchondroses are synarthroticAll synchondroses are synarthrotic
SymphysesSymphyses
Figure 8.2c
SymphysesSymphyses Hyaline cartilage covers the Hyaline cartilage covers the
articulating surface of the bone and articulating surface of the bone and is fused to an intervening pad of is fused to an intervening pad of fibrocartilagefibrocartilage
Amphiarthrotic joints designed for Amphiarthrotic joints designed for strength and flexibilitystrength and flexibility
Synovial JointsSynovial Joints Those joints in which the articulating Those joints in which the articulating
bones are separated by a fluid-bones are separated by a fluid-containing joint cavitycontaining joint cavity
All are freely movable diarthrosesAll are freely movable diarthroses
Examples – all limb joints, and most Examples – all limb joints, and most joints of the bodyjoints of the body
General StructureGeneral Structure Synovial joints all have the followingSynovial joints all have the following
Articular cartilageArticular cartilage Joint (synovial) cavityJoint (synovial) cavity Articular capsuleArticular capsule Synovial fluidSynovial fluid Reinforcing ligamentsReinforcing ligaments
General StructureGeneral Structure
Figure 8.3a, b
Friction-Reducing Friction-Reducing StructuresStructures
Bursae – flattened, fibrous sacs lined Bursae – flattened, fibrous sacs lined with synovial membranes and with synovial membranes and containing synovial fluidcontaining synovial fluid
Common where ligaments, muscles, Common where ligaments, muscles, skin, tendons, or bones rub togetherskin, tendons, or bones rub together
Tendon sheath – elongated bursa that Tendon sheath – elongated bursa that wraps completely around a tendonwraps completely around a tendon
Friction-Reducing Friction-Reducing StructuresStructures
Figure 8.4
Range of MotionRange of Motion Nonaxial – slipping movements onlyNonaxial – slipping movements only
Uniaxial – movement in one planeUniaxial – movement in one plane
Biaxial – movement in two planesBiaxial – movement in two planes
Multiaxial – movement in or around Multiaxial – movement in or around all three planesall three planes
StabilityStability Determined by:Determined by:
Articular surfaces Articular surfaces shape determines what movements are possibleshape determines what movements are possible
LigamentsLigaments unite bones and prevent excessive or unite bones and prevent excessive or
undesirable motionundesirable motion Muscle tone is accomplished by:Muscle tone is accomplished by:
Muscle tendons across joints acting as stabilizing Muscle tendons across joints acting as stabilizing factorsfactors
Tendons that are kept tight at all times by Tendons that are kept tight at all times by muscle tonemuscle tone
Range of MotionRange of Motion Nonaxial Nonaxial
slipping movements onlyslipping movements only Uniaxial Uniaxial
movement in one planemovement in one plane Biaxial Biaxial
movement in two planesmovement in two planes Multiaxial Multiaxial
movement in or around all three planesmovement in or around all three planes
Gliding MovementsGliding Movements One flat bone surface glides or slips One flat bone surface glides or slips
over another similar surfaceover another similar surface
Examples – intercarpal and Examples – intercarpal and intertarsal joints, and between the intertarsal joints, and between the flat articular processes of the flat articular processes of the vertebraevertebrae
Gliding MovementGliding Movement
Figure 8.5a
Angular MovementAngular Movement Flexion Flexion
bending movement that decreases the bending movement that decreases the angle of the jointangle of the joint
ExtensionExtension reverse of flexion; joint angle is reverse of flexion; joint angle is
increasedincreased
Angular MovementAngular Movement
Figure 8.5b
KneeKnee
Angular MovementAngular Movement
Figure 8.5c, d
Angular MovementAngular Movement Dorsiflexion and plantar flexion Dorsiflexion and plantar flexion
up and down movement of the footup and down movement of the foot Abduction Abduction
movement away from the midlinemovement away from the midline AdductionAdduction
movement toward the midlinemovement toward the midline CircumductionCircumduction
movement describes a cone in spacemovement describes a cone in space
Angular MovementAngular Movement
Figure 8.5e, f
RotationRotation
The turning of a The turning of a bone around its bone around its own long axisown long axis
ExamplesExamples Between first two Between first two
vertebraevertebrae Hip and shoulder Hip and shoulder
jointsjoints
Figure 8.5g
Special MovementsSpecial Movements Supination and pronationSupination and pronation Inversion and eversionInversion and eversion Protraction and retractionProtraction and retraction Elevation and depressionElevation and depression OppositionOpposition
Special MovementsSpecial Movements
Figure 8.6a
Special MovementsSpecial Movements
Figure 8.6b
Special MovementsSpecial Movements
Figure 8.6c
Special MovementsSpecial Movements
Figure 8.6d
Special MovementsSpecial Movements
Figure 8.6e