Articulations

ArticulationJoint between bones

Does not mean movement!Some joints are immovable; sutures.

Classification of joints

I) Functional definition "1)synarthrosis"!

2)amphiarthrosis"!

3)diarthrosis

Two questions about joints:

1- How does it move? - functional2- How is it held together?- structure

Immovable joint; sutures!

Partially movable; fibula and tibia (syndesmosis).

Freely moveable; knee, shoulder, fingers.

II) Structural definition

1)fibrous"!a) sutures"

!!Synostoses

Structure of the joint; how the joint is held together.

Lots of collagen fibers, usually dense CT; limited or no movement.

Skull- fibers anchors bone.!Fontanels- large areas of CT between fetal cranial bones.

Synostoses; Sometimes sutures fuse!No joint present- only bone.

b) syndesmoses"!

!

!

c) gomphoses

More fibrous CT, longer fibers!Similar to ligaments!Slight degree of motion; amphiarthrotic.!Tibiofibular joint.

Very dense CT layer!Between the alveoli of alveolar processes and teeth. !Synarthrotic.

2) Cartilaginous

a)synchondrosis"!

!

!

b)symphysis

Cartilage within the joint

Temporary cartilaginous joint!During the growth phase. !Immovable joint; epiphyseal plate.

Cartilaginous pad; between the two pubic bones.

3) synovial

Complex structure, diarthrotic. !

Joint cavity filled with synovial fluid.

StructureA) articular capsule"!

!!a) outer fibrous"!!!b) inner synovial membrane

Surrounds the joint and cavity.!Consists of...

capsule

Irregular dense CT, very fibrous; collagenous. !External sheath; holds joint together.

Lines the inside of the fibrous capsule !Boundary of the synovial cavity.!Produces synovial fluid.

B) joint cavity"!!!Synovial fluid

Fluid filled; between the bones of the joint."Free movement; protection of joint.

Fluid secreted by synovial membrane."Lubricating, nutrient rich material."Protects and maintains hyaline cartilage of the epiphyses

C) accessory ligaments"!

a) extracapsular ligaments"!

!

b) intracapsular ligaments

Additional mechanical support to the joint.

Located outside of the joint capsule.

Help stabilize the joint internally.

D) articular discs"!

!

intra-articular discs or menisci"!

!

E) bursae

Discs of fibrocartilage"Shape the internal surface of joint"Better fit between the bones.

Within the knee joint

Fluid filled sacs, cushion underneath ligament and tendons."Where the joint might experience extra stress or pressure.

Factors that allow some movement1) apposition of parts"!

2) fit of structures"!

3) strength and tension of ligaments"!

4) arrangement and tension of muscles

Soft structures limit how much a joint can move.

How bones fit together; defines the range of motion.

…determines range of motion.

…determines range of motion."Also help stabilize the joint.

1) gliding Movements

Bone “slides’ over the surface of another.No change in angle.

2) angular!

a) flexion/extension!b) abduction*!c) adduction*!d) rotation!e) circumduction

Motion defined by a change in angle

Decrease in angle, flexion; increase, extension.

Limb is moved away from the midline.

Limb is moved towards the midline.

Rotates around a axis

Complex series of motions combined into a single smooth motion"Pitcher winds up to pitch a ball.

16

3) special"a) inversion/eversion"

!

b) dorsiflexion/plantarflexion"

!

c) protraction/retraction"

!

d) supination/pronation"

!

e) elevation/depression

The foot; inversion- sole of the foot faces midline."Eversion- sole of the foot faces laterally

Foot; dorsiflexion- flexing the foot towards the shin."Plantarflexion- extending the foot towards the floor.

Structure is pushed out- protraction, or pulled in- retraction

Turning the palm to face anteriorly, supination."Turning the palm to face posteriorly, pronation.

Raising or lowering a structure, respectively.

Types of joints

1) gliding- arthrodial"2) hinge-ginglymus"!3) pivot-trochoid "!4) ellipsoid- condyloid"!5) saddle- sellaris"!6) ball & socket- spheroid

Types of movement a joint can produce

Flexion/extension

Rotation

Flexion/extension and abduction/adduction

Flexion/extension and abduction/adduction

Flexion/extension, abduction/adduction and rotation

Planes of movement

Nonaxial"!

Monaxial"!

Biaxial"!

Triaxial

Joint movement creates planes of movement

No angular change; gliding, arthrodial joint

Change along one axis; flexion/extension; ginglymus joint

Two axes; flexion/extension and abduction/adduction; condyloid and sellaris joints

Three axes; flexion/extension, abduction/adduction and rotation; spherical joint.

Tibiofemoral joint

3 joints"

!intermediate patellofemoral"

!lateral tibiofemoral"

!medial tibiofemoral

Knee joint

Largest and most complex in the body

Between patella and femur.

Between lateral condyle of femur and tibia.

Between medial condyle of femur and tibia.

articular capsule

extracapsular ligaments"

!

patellar ligament"

!

tibial collateral ligament*"

!

fibular collateral ligament

Capsule of the knee is not complete. Does not entirely surround the structures of the knee.

Knee ligaments; external support.

Anterior surface of the knee; inferior margin of patella to tibial tuberosity.

Medial surface of the knee; medial epicondyle of femur to the medial side of tibial head.

Lateral surface of the knee; lateral epicondyle of the femur to the lateral side of fibular head.

24

Intracapsular

Anterior cruciate*"!!!!

Posterior cruciate

Within the knee capsule

Anterior side of the joint cavity."Prevents the femur from sliding posteriorly

Posterior side of the joint cavity. "Prevents the femur from sliding anteriorly

articular discs"!!

!medial meniscus*"!!!!lateral meniscus"!

!!!*involved in injuries by lateral blow to the knee

Cartilaginous pads within the capsule; stabilize the fit of the bones.

On the medial condyle of tibia; fits with the medial femoral condyle.

On top of the lateral condyle of tibia; fits with the lateral femoral condyle.