There are six types of synovial joints and depending on the type there's going to be
different types of articulations between the two so how well the bones fit together and
that has implications in terms of what types of movement these synovial joints will allow
so we'll start with ball and socket joints we have a good idea we can visualize what a ball
and socket joint would be so the best example and the most freely movable joint here is your
shoulder joint the actual name for your shoulder joint is your glenohumeral joint so you're going to
have your ball on the humerus and your socket on the scapula all right so what's key here is how
well these actually articulate with one another so you have this fairly shallow socket the fairly
bulbous head of the humerus that's going to mean that you'd actually don't have a very good fit
between these two bones so this will allow for more movement in this region so these type of
joints are what's referred to as multi-axial so it can move in numerous axes so it can move
anteriorly posteriorly medial lateral and we'll talk about those different types of movements
in more detail so these are going to be the most freely moveable of your synovial joints
so think about where your other ball and socket joint is so we have your shoulder the other one
would be in your hip or your coxal joint so those are the two main examples of ball and
socket joints okay plane joints plane joints in terms of their articulating surfaces are
almost exactly flat so as you would see in this right here the the ends of the bones are almost
completely flat allowing for these bones to almost slide past one another okay so these
are typically bi-axial sometimes they can actually be multi axial as well one of the best examples is
your AC joint or acromioclavicular joint so the acromion process of your scapula and the lateral
end of your clavicle so you'll actually have a slight movement here in order for it to go up
down and sometimes even anterior and posterior pivot joints are exactly what they sound like
that's a good thing about these classification schemes are they are fairly intuitive into
what they're actually allowing with movement so pivot joint we have on here elbow joint but
it's a specific portion of your elbow joint your proximal radio-ulnar joint so when you have radio
think radius and then the ulnar so this proximal end of these two bones and as you can see here you
have this ligament right here which is going to allow for the radial head to pivot okay so you'll
have this slight pivot which is important in terms of your pronation and supination in this region
right here all right hinge joint this is another one that we think about quite a bit some of your
larger joints are going to be hinge joints we're looking right here at your true elbow joint or
your humero-ulnar so at this portion right here that's going to allow you to flex and extend
only in one axis so these are uni-axial joints another main hinge joint is your knee joint and
we'll talk a lot about the knee joint that's actually your most complex joint in your body
saddle joints so one of the articulating surfaces of saddle joints looks like a saddle yeah the
other bone looks like it's sitting within the saddle so the best example of that is
your first carpometacarpal joint so when you're thinking of your first digit or your thumb this
metacarpal where it's articulating with your trapezium bone one of your carpal bones now
there's actually quite a bit of movement that cannot be allowed here you can have
flexion extension abduction adduction and any time that you have flexion extension abduction
and adduction that allows for circumduction so if you can have those four complexes of
movement that allows for circumduction which allows for you to spin like this
okay same thing here in terms of your condylar joints just their articulating surfaces
are shaped slightly different differently so these metacarpophalangeal joints they're
not going to be as deep in terms of their articulation on your proximal phalanx and
this is not quite as bulbous as what you had with your saddle joints but same thing here
flexion extension abduction and adduction which will allow for some degree of circumduction