Bones and Joints Characteristics Joint Movement

Articulations  A joint, or articulation, is the place of contact between bones, between bone and cartilage, or between bones and teeth.  Bones are said to articulate with each other at a joint.

Classifications of Joints: Structural  Categorized structurally on the basis of the type of connective tissue that binds the articulating surfaces of the bones, and whether a space occurs between the articulating bones.  Fibrous  Cartilaginous  Synovial

Classifications of Joints: Functional  Can also be classified functionally based on the extent of movement they permit.  Synarthrosis: an immovable joint.  Amphiarthrosis: slightly movable joint.  Diarthrosis: freely movable joint.

Fibrous Joints  Structural Characteristics: Bones are held together by dense regular (fibrous) connective tissue.  Three Structural Categories:  Gomphosis  Suture  Syndesmosis

Fibrous Joint: Gomphoses  Periodontal ligament holds tooth to bony jaw.  Examples: tooth to jaw  Functional Classification: Synarthrosis (immobile)

Fibrous Joint: Suture  Dense regular connective tissue connects skull bones  Examples: Lambdoid suture (connects occipital and parietal bones).  Functional classification: synarthrosis (immovable)

Fibrous Joint: Syndesmosis  Dense regular connective tissue fibers (interosseous membrane) between bones.  Examples: articulation between radius and ulna, and between tibia and fibula.  Functional classification: amphiarthrosis (slightly movable)

Cartilaginous Joints  Pad of cartilage lies between the ends of bones; no joint cavity.  Two structural categories:  Synchondrosis  Symphysis

Cartilaginous Joints: Synchondrosis  Hyaline cartilage plane between bones.  Example: epiphyseal plates in growing bones; costochondral joints  Function classification: synarthrosis (immobile)

Cartilaginous Joints: Symphysis  Fibrocartilage pad between bones.  Examples: public symphysis (between ossa coxae); intervertebral disc articulations.  Functional classification: Amphiarthrosis (slightly movable).

Synovial Joints  Ends of bones covered with articular cartilage; joint cavity separates the articulating bones; enclosed by a joint capsule, lined by a synovial membrane; contains synovial fluid.  ALL ARE DIARTHROSIS (FREELY MOVEABLE)  Three structural categories:  Uniaxial  Biaxial  Multiaxial (triaxial)

Synovial Joints: Uniaxial  Have three subcategories:  Planar joint: flattened or slightly curved faces slide across one another (examples: planar joint, intercarpal joints, intertarsal joints)  Hinge joint: permits angular movements on a single plane (example: elbow {humeroulnar} joint)  Pivot joint: permits rotation only (example: atlantoaxial joint)

Synovial Joints: Biaxial  Have two subcategories:  Condyloid joint: oval articular surface on one bone closely interfaces with a depressed surface on another bone (example: MP {metacarpophalangeal} joints  Saddle joint: saddle-shaped articular surface on one bone closely interfaces with depressed surface on another bone (example: articulation between carpal and first metacarpal bone)

Synovial Joints: Multiaxial  Only one type:  Ball and socket joint: round head of one bone rests within cup-shaped depression in another bone (example: glenohumeral joint, coxal joint)

Movements of Synovial Joints MovementDescriptionOpposing Movement AbductionMovement of a bone away from the midline Adduction Movement of a bone toward the midline Abduction FlexionThe angle between articulating bones decreases Extension The angle between articulating bones increases Flexion Hyperextensio n Extension movement continues past the anatomic position Flexion Lateral FlexionThe vertebral column moves in either lateral direction None CircumductionA continuous movement that combines flexion, abduction, extension, & adduction in succession (moves in circle) None

Movements of Synovial Joints MovementDescriptionOpposing Movement DepressionMovement of a body part inferiorlyElevation Movement of a body part superiorly Depression DorsiflexionAnkle joint movement where the dorsum of the foot is brought closer to the posterior surface of the leg Plantar Flexion Ankle joint movement where the sole of the foot is brought closer to the posterior surface of the leg Dorsiflexion EversionTwisting motion of the foot that turns the sole laterally or outward Inversion Twisting movtion of the foot that turns the sole medially or inward Eversion

Movements of Synovial Joints MovementDescriptionOpposing Movement PronationMovement of the forearm where the palm is turned posteriorly Supination Movement of the forearm in which the palm is turned anteriorly Pronation ProtractionMovement of a body part anteriorly in the horizontal plane Retraction Movement of a body part posteriorly in the horizontal plane Protraction OppositionSpecial movement of the thumb across the palm toward the fingers to permit grasping and holding of an object Reposition