Hello anatomy friends this is Dr Alsup and in this video we will be identifying the largest
and major joints of the upper limb. As is the theme for this session we are not going into
great detail here but rather our goal is to familiarize ourselves with the basic location
and the bony compartments. So starting in the shoulder region there are two joints that I want
you to begin to get familiar with starting with the more proximal one the acromioclavicular joint.
This is where the acromial end of the clavicle articulates with the acromion of the scapula
and this will form the AC joint. This is a joint that we palpated on the very first day of anatomy
as it's an easier one to locate. You can palpate your clavicle
and continue laterally until you reach a bump and you are at the acromioclavicular joint.
The AC joint is not a particularly mobile joint, you can see it here as well, but its slight
movements are important in allowing the full range of motion at the most mobile joint of the body,
which is the glenohumeral or shoulder joint, and you've got to love that shoulder joint for many
reasons. It's complicated, as mentioned it is the most mobile joint of the body
but also one of the least stable and with decreased stability
there is an increase of injury which is certainly true for the shoulder joint.
The joint is formed by the articulation of the glenoid fossa of the scapula which is
relatively shallow particularly in comparison to the relatively large humeral head, so the fit
is not the best so there are numerous accessory structures and the rotator cuff throughout to
provide stability, so you can see here where the shoulder joint would be but of course we have that
joint capsule right there, and you can see a little bit of the head right there articulating with the
glenoid cavity. Moving distally we reach the elbow region where you really have three joints in one
region. The major joint and the one that we mean when we say elbow joint is the humeroulnar joint
which is right here. Now this joint is more medially placed so this is going to be medial
this will be lateral mainly because you have that trochlea here the medial epicondyles right here.
And this is what's really forming that true hinge joint. Not on the list but neighboring
is the humeroradial joint which will further support the movements of the elbow joint.
Just distal to both of these is the proximal radioulnar joint so proximal radioulnar joint.
The radius and the ulna will articulate in three separate areas which in essence forms
three different joints. The proximal radioulnar as the name would suggest
is the most proximal of these and this is formed by the head of the radius and the
radial notch of the ulna and it allows that head to rotate the head of the radius to rotate.
These are the other two joints formed by the radius and the ulna. The longest and
only observable and deepest dissections is the interosseus membrane which is this whole kind of
sheet of connective tissue that is connecting the bodies or the shafts of the radius and the ulna.
This is actually not a synovial joint it's a fibrous joint it will further allow the actions
that can occur between the the radius and the ulna. The distal radioulnar joint is the distal most
right above the wrist joint and this is formed by the ulnar notch of the radius and the head of
the ulna so right here is the distal radioulnar. All three of these radioulnar joints will allow
the movements of pronation and supination that we will discuss in more detail in upcoming sessions.
Lastly we have the wrist joint which is also called the radiocarpal joint
because it is formed by the distal end of the radius
and the first or proximal row of the carpal bones which would be deep to this region
here so in essence the radiocarpal or wrist joint is right here in this region.
As you can see it's quite protected by
ligaments as well as kind of fascia in this region but it is still one of your larger
synovial joints. Excellent here is an overview with a bit more context regarding the joints we just
discussed, in terms of relationships with other bones. The AC and glenohumeral joints are up here
that are proximally located. In the elbow region we have the complex of three joints we have that
humeroulnar the humeroradial I assure you this is spelled right I don't know why that
that's that little line is there and then we have not circled here but the proximal radial
ulna right there. The interosseous membrane would be kind of right in this region here
so it'd be that connective tissue connecting these the shafts or the bodies of these bones
with the distal radioulnar right here and then of course we have the
radiocarpal or wrist joint which is formed by that distal radius and this first
or proximal row of carpal bones those small bones of the wrist. And note that
this ulna does not play an articulating role in the radiocarpal or wrist joint.
Alright great thank you for your time and attention here and have a great rest of your day.