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Articulations

 

 

A Classification of Joints

Articulations

      Articulations

    Where two bones interconnect

      Immovable joints

    Synarthroses, or bony

      Slightly moveable joints

    Amphiarthroses, or fibrous / cartilagenous

      Freely moveable joints

    Diarthroses, or synovial

 

Synarthroses (immovable joints)

      Four major types

    Suture = skull bones bound together by dense connective tissue

    Gomphosis = teeth bound to bony sockets by periodontal ligaments

    Synchondrosis = two bones bound by rigid cartilaginous bridge

    Syntosis = two bones completely fused

 

Amphiarthroses (slightly movable joints)

      Two major types

    Syndesmosis = bones connected by a ligament

    Symphysis = bone separated by fibrocartilage

 

Diarthroses (freely movable joints)

      Bony surfaces enclosed within articular capsule

      Bony surfaces covered by articular cartilage

      Bony surfaces lubricated by synovial fluid

      Structures include

    Menisci

    Fat pads

    Accessory ligaments

    Bursae


Articular Form and Function

Dynamic motion

      Dynamic motion

    Linear motion

    Angular motion

    Rotation

      Joints classified based on type of motion permitted

    Monaxial

    Biaxial

    Triaxial

 

 

Types of movement

      Gliding motion

    Two surfaces slide past one another

      Angular motion

    Flexion, extension, hyperextension

    Abduction, adduction

    Circumduction

 

 

Rotational movement

      Left or right

      Medial (internal) or lateral (external)

      Pronation or supination in the bones of the forearm only

 

 

Special movement

      Movements of the foot

    Inversion and eversion

    Plantar flexion and dorsiflexion

      Movements of the thumb

    Opposition

 

Other movements

      Protraction moves a structure anteriorly

      Retraction moves a structure posteriorly

      Elevation moves a structure superiorly

      Depression moves a structure inferiorly

      Lateral flexion bends the vertebrae to one side

 

Structural classification of joints

      Gliding joints permit movement in a single plane

      Hinge joints are monaxial joints permitting angular motion in one plane

      Pivot joints are monaxial joints that permit rotation

      Ellipsoid joints are biaxial joints that pit one bone in an oval depression of another

      Saddle joints are biaxial joints with one concave and one convex bone face

      Ball-and-socket joints are triaxial joints that permit rotation and other movements


Representative Articulations

Intervertebral articulations

      Gliding joints

      Vertebral bodies form symphyseal joints cushioned by intervertebral discs

    Outer anulus fibrosus and inner nucleus pulposus

      Stabilized by ligaments

 

Shoulder joint (glenohumoral joint)

      Glenoid cavity and head of humerus

      Ball and socket diarthroses

      Stabilized by ligaments

      Strength and stability sacrificed for range of motion

 

The elbow joint

      Permits only flexion and extension

      Hinge diarthroses

      Reinforced with strong ligaments

 

Hip joint

      Ball and socket diarthroses

      Acetabulum and head of femur

      Permits flexion/extension, abduction/ adduction, circumduction, rotation

      Stabilized by numerous ligaments

 

Knee joint

      Hinge joint with incomplete articular capsule

      Formed by the condyles of the femur and the condylar surfaces of the tibia

      Accessory structures help stabilize lateral movements

      Permits flexion/extension, limited rotation

      Supported by ligaments


Aging and Articulations

Joint problems with aging

      Joint problems associated with aging

    Relatively common

    Rheumatism general term for pain and stiffness in muscular and skeletal elements

    Arthritis all rheumatic diseases affecting synovial joints


Bones and Muscles

Musculoskeletal system

      Encompasses the extensive interactions between the muscular and skeletal systems