Arthrology. Chapter 9. Arthrology Is…. Study of joints Joints are defined as places where the rigid elements of the skeleton meet. HOWEVER, joints can be between the “soft” parts of the skeleton. Classification of Joints. 2 Methods of Classification Functional Classification
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2 Methods of Classification
*focuses on the amount of movement
*focuses on the material that binds
the joint together.
- called a synarthrosis or syndesmosis
- is a bone to bone union
- begins as a joint where there is a fibrous membrane between the two bones. They are sometimes called FIBROUS JOINTS or LIGAMENTOUS UNIONS.
- These are NON-MOVEABLE
- Fontanelles are examples
- moveable and immoveable
- cartilage between two bones
- these joints allow some movement while still providing protection.
- allow for free movement
- have three characteristics:
1. synovial membrane
- a serous membrane that produces synovial fluid which reduces friction and absorbs shock.
2. articular cartilage
-dense connective tissue covering the joint
The articular cartilage acts similarly to “teflon”, which helps reduce friction and pressure.
The joint capsule covers and protects the synovial membrane.
Intracapuslar Ligament – hold the bones together. Not found in every joint.
Extracapsular Ligament – called the collateral ligament. It is a single band that is actually a thickening of the joint capsule.
Flexion vs. Extension
Dorsiflexion vs. Plantarflexion
Abduction vs. Adduction
Pronation vs. Supination
Protraction vs. Retraction
Elevation vs. Depression
Inversion vs. Eversion
- allow for the most freedom of movement
- triaxial movement – flexion, extension, abduction, adduction, circumflexion, and rotation
- uniaxial – allows movement in only one direction. Back and Forth
- allows only flexion and extension in one plane (sagittal)
- many times the articular surfaces will have a distinct shape (ie: spool shaped trochlear surface of the humerus)
- allows rotation (uniaxial)
- rounded, pointed, or conical surface on one bone that fits into a ring of bone on another.
- allows flexion, extension, abduction, adduction, and circumduction.
- surfaces are inverted relative to each other.
- one bone is concave (hollowed out depression) and the other is convex (rounded or elliptical).
- allows flexion, extension, abduction, and adduction.
- NO ROTATION
- side to side, back and forth
- two flat surfaces that slide over each other
- NO ANGULAR MOTION
- one side is a slot, the other side is an extension that fits into the slot.
- NO SIDE TO SIDE MOVEMENT
- Allows flexion and extension
This type of lever pulls our head into an extended position once flexed.
The muscles that elevate us to our tip toes – plantarflexion of the foot on the leg.
The load is opposite the fulcrum.
Examples of this type of lever are muscles that move the forearm.
- nerve impulse
- the joint must allow for movement in plane that the muscle shortens.
- the muscle must be able to pull the load
- force must be greater than the resistance
AGONIST – assists movement
ANTAGONIST – resists movement
For example: The triceps surae (gastrocnemius and soleus complex) plantarflexes the foot on the leg. This is the plantarflexory agonist. The muscles that work against the triceps are the dorsiflexory muscles (tibialis anterior and long extensors).
The opposite is also true: The plantarflexors are the antagonists to the dorsiflexors.
1. Plane 4. Condyloid
2. Hinge 5. Saddle
3. Pivot 6. Ball and Socket
simple joint – 2 articulating surfaces
compound joint - >2 articular surfaces
1. fibrous capsule – outside, dense irregular CT that is continuous with the periosteum.
2. synovial membrane – loose CT. Makes synovial fluid for protection.
*viscous fluid resembling raw egg whites.
*filtrate of blood
*bands that hold the joint together.
*Extracapsular – outside the capsule
*Intracapsular – internal to the capsule
*Nerves and Blood Vessels
*Detect pain when joint is disrupted (ie: sprains,
1. Gliding – sliding of flat surfaces across each other. Found mainly between the carpals and between the tarsals.
2. Angular – increase or decreases the angle between the two bones
3. Rotation – movement of bone around its long axis.
1. plane – flat articular surfaces. Short gliding movements are allowed.
2. hinge – cylindrical end of one bone fits into the trough of another bone. Angular movement is in one plane. Uniaxial joint along one plane.
3. pivot – rounded end of one fits into a ring formed by another bone.
- stretching or tearing of a ligament
- joint alignment is interrupted
- Subluxationis a partial or
incomplete dislocation of a
- inflammation of a bursa
- Bursae are sacs of fluid that serve to
protect boney prominences.
- inflammation of a tendon sheath
- most common type of arthritis
- degenerative condition of the
- Enzymes wear down the cartilage
matrix due to “wear and tear”
- inflammation of the synovium
- autoimmune in origin
- often results in ankylosis of the joint