hello anatomy friends i am wildly excited to get into the appendages and we are going to start
with the superior most appendage or the upper limb and then we will continue our way and finish our
discussion with the lower limb so as always we're going to start with bones but there are so many
bones associated with the upper limb that we're going to have a few videos and we're going to
kind of break them down regarding their region so we're going to start with the pectoral girdle
so first we'll kind of talk about the overarching uh functions of the upper limb just since this is
our first video of the upper limb but then we're going to get down into the main bones of the
pectoral girdle which are the clavicle and the scapula okay so when i think of the upper limb
the first thing that comes to mind is mobility all right think about moving your upper limb
and a lot of times when you move your upper limb often you're moving that shoulder but you can
move other joints uh it has considerable mobility or more mobility than its partner down here in
terms of the lower limb so lots of mobility there will be some other issues so with less mobility
you're kind of giving up some of the stability particularly in terms of the shoulder joint region
but of course with the lower limb it's dealing with a lot more weight
than what we have in the upper limb so lower limb is a lot more weight bearing
upper limb not so much but it does play a very important role in terms of grasping and fine
motor skills particularly as we get to some of the more distal portions of the upper limb
we generally divide the upper limb into four major regions we're going to have the shoulder the arm
or the brachium and so this whole thing is not the arm colloquially we refer to the upper limb
as the arm but it's only this portion that is considered the arm and even a little bit higher
sometimes the forearm or the antebrachium and then we have the hand and the wrist region right here
okay so returning to those superior most portions of the upper limb bones and that
is the pectoral girdle and this is really how we are going to have a connection to the thorax
uh to the upper limb and we'll have something similar and we talked about it with the pelvic
girdle so you have the hip bones articulating with the sacrum well these two bones the clavicle and
the sternum are not directly articulating with the vertebral column but they are going to articulate
at least in terms of the clavicle very directly and indirectly for the scapula the thoracic cage
so the clavicle is this beautiful little s shaped bone that you can palpate your own you can palpate
your clavicle almost its entire length so it's going to be anteriorly placed right at the root of
the neck region there's that sternum right there that we are hopefully familiar with and the ribs
right here the sternal end as we have mentioned in previous videos are is going to articulate
with the manibrium or that superior most portion of the sternum at the sternoclavicular joint
and then the lateral end of the bone is going to articulate with the scapula specifically
the acromion portion of the scapula and you if you follow your clavicle from medial to lateral
you can feel that bump kind of at the end there and that is the acromioclavicular
joint or your ac joint the clavicle is one of the most frequently fractured
bones in the body sometimes you'll hear it referred to as the most frequently fractured but
you see different numbers on different studies so i'm not going to say the i'm going to say
one of the most frequently fractured and it's particularly common in children and often what
is happening is you're going to have an indirect force that is going to be transmitted from the
more distal portions of the upper limb all the way up to the clavicle so if you think of falling
and if you're falling you often will kind of stretch out your hand to to kind of stop your
fall or kind of keep your head from hitting the ground and so that outstretched hand
is going to allow for the force to kind of move up through the upper limb and often will lead
um to a fracture and usually the weakest part is going to be kind of in this junction of the
the middle and lateral thirds region and with contraction of the pectoralis muscles
um it could lead to the fracture getting more severe in terms of um not or misaligned
so it kind of takes that immobility of a lot of the structures around there and the muscles
to keep the the two clavicular fractured parts close to one another to allow for healing to occur
all right moving to the scapula the scapula is beautifully
irregularly shaped but also flat bone or flat portion of bone right here
what you are seeing here is kind of an anterior view of the pectoral girdle and you can see
that a portion of the scapula will project anteriorly and this is going to be the coracoid
process so you can see it quite beautifully right here it supposedly resembles a crow's beak
and as mentioned it's going to be superior to the glenoid cavity which is the portion that's
going to articulate with the humerus and will project anterior laterally and it's a process
and if you know remember our terminology in terms of what processes are with bone often
that means it's an attachment side and that's exactly what the coracoid process
is it will be the attachment site or the distal attachment site for the pectoralis minor muscle
as well as one of the heads of the biceps brachii specifically the short head and then
all kinds of ligaments as well we'll talk about those when we talk about
the different joints in this region particularly the acromioclavicular joint
now if you pat yourself on the back you may feel this prominent projection right here which is the
spine of the scapula so this is on the posterior surface we're looking at a posterior view
and you'll have this dominant projection that will project posteriorly and it will continue
and then once we get to about hereish we really have a name change and the bone kind of extends
and expands into the acromion and sometimes you hear this referred to as the acromial process
and a lot of times we talk we say this is the point of the shoulder
particularly kind of where that acromioclavicular joint happens you can really feel that that's
that's a nice prominent bump you can often see it underneath an individual's skin and so that is
kind of the point of the shoulder and oftentimes you like physicians will compare the two points
of the shoulders to see if one is a little bit higher a little bit lower than the other
that could have some indication of some type of shoulder pathology or something along those lines
and last but not least is the beautiful glenoid fossa sometimes you'll hear it referred to as the
glenoid cavity and so this is going to um be where we have the this is the socket portion of the
glenohumeral or shoulder joint all right now look at this thing we we talked about the acetabulum
when we were talking about the pelvic girdle and the hip bones it was a fairly significantly deep
structure compare that with this glenoid fossa right here this fossa is relatively shallow and
the humeral head which we'll see in some upcoming videos is relatively large so you do not have an
excellent fit between the glenoid fossa and the head of the humerus
and so this has a lot to do with the instability or the relative instability of the shoulder joint
and the relative mobility of the shoulder joint just because the fit here is just not as
tight as what we have in other joints and again this is a joint surface so it is nice and smooth
because articular cartilage would have sat there during life all right so our question
regarding the pectoral girdle bones the lateral continuation of the scapular spine is
what osteological structure and the structure will articulate with the clavicle so lots and
lots of clues here lateral continuation of the scapular spine so it's basically of the scapular
spine just continuing laterally and then this is a big old hint it articulates with the clavicle
well the coracoid process there may be some ligaments that kind of head that way but that is
going to be more anteriorly placed and it doesn't have anything to do with the scapular spine
other than being in close proximity but not a continuation glenoid fossa is going to be the
socket portion of the glenohumeral joint so this is not going to be a continuation of the spine
so that leaves a acromion or acromial process as the correct answer and if you're looking here it's
nice and quite obvious you can see the spine of the scapula and you can see it continuing
and getting larger and wider as the acromion thank you for your time and attention here
review these structures and we will talk about them a little bit again when we're talking about
the lab as well take your time ask questions early and often and please have a great rest of your day