Joints
Joints
• Now that we know all of
the bones we need to
look at the joints of the
skeleton
•
Joints, also called
articulations, have two
main functions
•
They hold bones
together securely
•
They give the rigid
skeleton mobility
Classification of joints
•
Joints are commonly
classified in two manners
•
Functionally -- how they
work
•
Structurally -- how they
are constructed and
shaped.
Functional Classification
•
The functional
classifications focus on
the amount of movement
allowed by the joints
•
With this system we have
3 main categories
•
Synarthroses
•
Amphiarthroses
•
Diarthroses
Synarthroses
•
Synarthroses joints are
joints that are
immoveable
•
Most commonly located
in the axial skeleton
•
Ex: joints of the large
bones of the cranium like
the tempro-parietal joint
Amphiarthroses
•
Amphiarthroses are joints
that are slightly movable.
•
These joints, like
synarthroses are mostly
located in the axial
skeleton where rigidity is
important to the function
of the bones.
Diarthroses
•
Diarthroses are joints
that are freely movable
•
These are mostly found
in the appendicular
skeleton, whose main
function is mobility and
manipulation.
Structural Classification
•
We can also classify the
joints by there structural
classifications
•
We also have 3 structural
classifications
•
Fibrous
•
Cartilaginous
•
Synovial
Fibrous Joints
•
Fibrous joints are joints
that are united by fibrous
tissue
•
The best examples of
this type of joint are the
sutures in the skull
•
In sutures we have the
jagged edges bound
tightly together with
connective tissue fibers
Fibrous joints
•
Sutures are not the only
place for fibrous joints
•
There are some places
where the connecting
fibers are larger and
longer to allow more
“give”
•
These are called
syndesmoses
•
An example is between
the distal end of the
fibula and tibia
Cartilaginous Joints
•
These are the joints
connected by cartilage
•
Examples of this type of
joint are usually slightly
moveable
•
The joints between the
vertebrae are
cartilaginous joints
Synovial Joints
•
Synovial joints are those
in which the articulating
surfaces are seperated
by a joint cavity
containing synovial fluid
•
All Synovial joints have 4
distinguishing features.
Features of synovial joints
•
Articular cartilage
•
Fibrous articular capsule
•
Joint Cavity
•
Reinforcing Ligaments
Types of synovial joints
•
There are 6 types of
synovial joints
•
Plane
•
Hinge
•
Pivot
•
Condyloid
•
Saddle
•
Ball-and-Socket
Plane Joint
•
A plane joint can be seen
in your carpals
•
It moves very limitedly
Hinge joint
•
A hinge joint can be
found in your humerus
where it connects to the
ulna
•
This allows motion
similar to a hinge of a
door
Pivot joint
•
Pivot joints can be found
in your radius and ulna
as well as your vertebrae
•
They allow for twisting
motion
Condyloid joint
•
Condyloid joints provide
motion to the sides like a
joystick
•
An example would be
your metacarpals and
metatarsals
Saddle joint
•
A saddle joint is shaped
like a saddle and provide
for motion back and forth
and side to side
•
An example would be
where your metacarpal 1
meets your carpals
Ball and socket joint
•
Ball and socket joints
provide the most
movement out of all the
joints
•
They allow for nearly 360
degrees of rotation
•
They can be found in the
heads of your humerus
and femur