hello all this is dr allsup and we will be discussing the joints in the shoulder region
namely we will be focused on the acromioclavicular joint and the glenohumeral joint better known as
the shoulder joint so a quick review regarding bony articulations the acromioclavicular joint
is formed by the articulation of the acromial or lateral end of the clavicle and the acromion
of the scapula and this will form the acromioclavicular joint which is a plane
joint so slight movements occur here conversely a wide range of movements can occur at the ball and
socket glenohumeral joint which is formed by the socket which is the glenoid fossa
of the scapula and the ball which is the head of the humerus and notice how close
these joints are to each other the ac joint is located just superior to the shoulder joint
let's discuss accessory structures associated with these joints starting with the coracoclavicular
ligament and the name of this ligament gives you all the clues regarding where it's located
this will be located between the coracoid process of the scapula and the clavicles of the coracoid
process and then clavicle so you can see it's a rather robust ligament shaded in light blue
here so coraco clavicular and you can see it over here on this image that's not shaded so
the coracoid process is right here this is the clavicle and so right here would be the
coracoclavicular ligament this ligament plays a very important role in the integrity and stability
of the acromioclavicular joint so severe shoulder separations often involve damage to this ligament
here shaded in purple is the coracoacromial
ligament which extends between that coracoid process and the acromion i actually like it better
here on this unshaded image so here's the coracoid process again and here is the acromion and you can
really see the expanse of this ligament and you can see how the ligament so the coracoacromial
ligament as well as its bony attachment sites are forming an arch so the coracoacromial arch
will be located right in this region and this allows for structures that are going
to or from the shoulder joint region to travel deep to the cracoacromial arch
this whole shiny opaque region right here is going to be the capsule
of the glenohumeral joint so the joint capsule the that's the reason why we can't see the
glenoid fossa and the head of the humerus on these dissections because it's the capsule surrounding
and protecting these structures so this this is the capsule i often get asked during dissections
what is this ligament here why can't i move it why can't i see that the head of the humerus or
say the glenoid fossa and it's all because you've reached the ac the actual capsule which can be
quite strong in many locations joint locations a major player in the shoulder joint region are
the rotator cuff tendons which form the nearly complete cuff of tendon around the shoulder joints
with only a slight inferior deficiency and these tendons are really the major source of stability
to this region you can follow the muscle bellies of these muscles
laterally so you can see three of them here this is a rotator cuff muscle rotator cuff muscle
rotator cuff muscle and you can follow them laterally and you can see where
it's just becoming opaque and kind of white in this region and that's where the tendons are
and the same thing here and you can almost see it a little bit better here
you have this one anteriorly placed rotator cuff muscle and its tendon kind of gets lost
right about here-ish and that's because it becomes intermingled with the joint capsule
of the shoulder joint so you can really see how that tendon is kind of crossing over this region
intermingling with the capsule and you're really having that that strong protection in this region
lastly i want to mention the labrum the labrum is a fibrocartilaginous lip that's located it
or it circumscribes the glenoid fossa allowing a slightly better fit between the articulating bones
you really only find labra associated with ball and socket joint so you have one here with the
shoulder joint you'll have one with the hip joint as well and this isn't a particularly
great image of the labrum you can see that the joint capsule has been incised here
in order to get a slight view into the actual joint and you can see a bit of the labrum
so this would be right about here would be the glenoid fossa and you can see a bit of the
labrum right in this region but again the labrum kind of traces the borders of the glenoid fossa
and usually if you have a direct view if you're looking straight at the glenoid fossa that's
typically where you can see the labrum better otherwise if you're looking kind of right here
like we are it's hard to differentiate it between the surrounding joint capsule
all right excellent thank you for your time and attention as i discuss my favorite
joint the shoulder joint i hope you have a great rest of your day