Bones and JointsCharacteristicsJoint 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 JointsMovement Description Opposing

Movement

Abduction Movement of a bone away from the midline

Adduction

Adduction Movement of a bone toward the midline

Abduction

Flexion The angle between articulating bones decreases

Extension

Extension The angle between articulating bones increases

Flexion

Hyperextension

Extension movement continues past the anatomic position

Flexion

Lateral Flexion The vertebral column moves in either lateral direction

None

Circumduction A continuous movement that combines flexion, abduction, extension, & adduction in succession (moves in circle)

None

Movements of Synovial JointsMovement Description Opposing

Movement

Depression Movement of a body part inferiorly

Elevation

Elevation Movement of a body part superiorly

Depression

Dorsiflexion Ankle joint movement where the dorsum of the foot is brought closer to the posterior surface of the leg

Plantar Flexion

Plantar Flexion

Ankle joint movement where the sole of the foot is brought closer to the posterior surface of the leg

Dorsiflexion

Eversion Twisting motion of the foot that turns the sole laterally or outward

Inversion

Inversion Twisting movtion of the foot that turns the sole medially or inward

Eversion

Movements of Synovial JointsMovement Description Opposing

Movement

Pronation Movement of the forearm where the palm is turned posteriorly

Supination

Supination Movement of the forearm in which the palm is turned anteriorly

Pronation

Protraction Movement of a body part anteriorly in the horizontal plane

Retraction

Retraction Movement of a body part posteriorly in the horizontal plane

Protraction

Opposition Special movement of the thumb across the palm toward the fingers to permit grasping and holding of an object

Reposition