Hello anatomy friends this is Dr Alsup and in this video we are going
to start putting some names to the muscle compartments and groups in the upper limb.
So not only are we going to name these muscle compartments but we're going to locate them,
so we're going to get an understanding of the general location of these groupings of muscles.
And one of the more complex regions of the upper limb is the shoulder region. You will have
muscles that are larger and span in terms of attachment sites both the axial as well as the
appendicular skeletons. And these are referred to as the axioappendicular muscles. And we've
discussed many of these in previous sessions such as the trapezius as well as the latissimus dorsi
and those pectoralis muscles as we were dissecting the areas of their proximal attachment so the
superficial back or the anterior thorax. But their distal attachments will be on either the scapula
or the humerus thus affecting the actions of the pectoral girdle or shoulder joint.
So important to consider these muscles again. There will also be shorter but still very
important muscles that proximally and distally attach within the shoulder region and affect
the actions of the shoulder joint. So typically an attachment on the scapula and then on the humerus
and these are referred to as intrinsic shoulder muscles. And we'll discuss the specific muscles in
upcoming sessions but these will include the deltoid and then of course the rotator cuff.
Moving distally from the shoulder into the arm or scientifically referred to as
the brachium region, we often use the term arm to mean the whole upper limb however that is
not correct. the arm is this specific area so where the humerus is located.
And there are two major compartments here and very fortunately there is a
similar organization in the forearm as well. Anterior compartments which you can see here,
are as their name would suggest anteriorly located. These compartments are often referred to as flexor
compartments as these muscles located here will play a role in flexion of in this particular case
the elbow joint. We will discuss the actions in a bit more detail on upcoming learning objectives.
The posterior compartment of the arm is located posteriorly and the muscles
located here will serve to extend primarily the elbow joint. And I keep saying primarily
as these muscles most powerful movements will often affect the elbow joint but these muscles
may also affect other surrounding joints but right now we are talking big picture big generalizations.
So a very similar organization in the forearm as what we saw in the arm with
an anterior and flexor we're adding in another action here as well as a posterior extensor
compartment. And again we'll talk more about these specific actions and upcoming learning objectives.
However I do want to note that the forearm this area
becomes more complex than what we had in the arm in two major ways.
First the forearm there are considerably more muscles in the forearm than in the arm.
Secondly these muscles have more variability in terms of which joints they most forcefully
affect. But and these joints will include the various radioulnar joints the wrist joint
and joints of the hand and these muscles are those examples of those
long tendons. So we have the muscle bellies actually in the forearm but the tendons will
actually extend for many of these muscles all the way to the digits in many cases.
Lastly there are numerous compartments of the hand specifically
but we're going to focus on two prominent ones here in this big picture overview. These
muscles these hand muscles with those forearm muscles whose tendons extend into the hand
will affect the actions at the joints of the hand. Note these do not affect these specific muscles
that are located solely only within the hand do not affect the actions of the wrist joint.
There is a fairly dominant thenar compartment of muscles which is
located on the thumb side or that first digit which is lateral. And then there is a hypothenar
compartment of muscles on the pinky finger or fifth digit side which is medially located when
you're thinking an anatomical position. Remember the palms face anteriorly in anatomical
position. There are certainly additional muscles in the hand and these tend to be located deeper
than those in the thenar and hypothenar compartments and we aren't going to get in
those specifics as they are not particularly foundational. Excellent we have reached the
summary slide and I appreciate your time and attention here. Have a great rest of your day