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