This video is going to focus on the humerus and the humerus is going to be the longest bone
associated with your upper limb and it's going to make up the entirety of the arm portion of
the upper limb so one thing I want to start with is trying to figure out which end is proximal and
which end is distal so the proximal end is going to have the bulbous head so this is
what's articulating with the scapula in order to form the glenohumeral joint or the shoulder joint
the distal end is a bit more complex in terms of what it looks like it has these epicondyle
projections and then when you're looking posteriorly it has this very distinct depression where the
ulna is going to articulate to form the elbow joint when trying to determine if you're looking
at a right or a left humerus I always look at the head of the humerus first that's always got to be
facing medially and if you think about it that makes sense it's got to be right in this region
in order to form the shoulder joint alright so let's talk about a few of the structures that
you need to understand in order to get a better understanding of the humerus so the first thing is
this head like I said this is forming a portion of the glenohumeral joint and one thing about
the shoulder joint is that it's the most freely moveable has the largest range of motion of any of
your synovial joints and that has a lot to do with the fit of the bones you have this fairly robust
head that's going to fit in with a very shallow glenoid cavity of the scapula so the fit of the
bones is not very good that will allow for a bit more movement so less stability but more mobility
now right next to it you'll have a pinching kind of surrounding the head of the humerus this is
referred to as the anatomical neck and just below it you'll have another neck this area is
referred to as the surgical neck it is clinically important because you're gonna have neurovasculature
that's going to surround this anatomical neck and as you can see this is a little bit skinnier than
other portions of the humerus so it's a bit more susceptible for fracture so what could happen when
you have a fracture of your surgical neck is that the axillary nerve will be compromised and that
axillary nerve is going to innervate the deltoid muscle so if you have deactivation in terms of
the deltoid that will play a big role in terms of abduction of your arm all right there's a complex
of tubercles and anytime that I utilize the term tubercles it means the building up of bone you can
see just a building up a bone that typically is indication that a muscle is going to attach there
so the larger the tubercle the more muscles attached there and that's the case in terms of
the greater tubercle the greater tubercle is always the opposite to the head and you're
gonna have three of your rotator cuff muscles that are going to attach here you're gonna have your
supraspinatus your infraspinatus and your teres minor now anteriorly facing you'll have your lesser
tubercle so as the name would suggest it's going to be smaller than the greater tubercle and this
is where that fourth muscle of the rotator cuff complex is going to attach your subscapularis
now also anteriorly you'll see a space between your greater and your lesser tubercle nice little
divot right there this is where the tendon of your biceps brachii is going to travel in order
to have an attachment to the scapula so we all know our biceps brachii is what's forming the
bulk of the upper limb portion right here so when you're flexing your elbow that biceps brachii is
really contracting ok so let's move distally now associated with kind of a little bit lateral but
also heading more posteriorly this is going to be the distal attachment for your deltoid muscle
so this is a really good indication of whether an individual's big exerciser or not so anybody
that's a bodybuilder is gonna have a really big mounding of bone right here if their deltoids
or hypertrophied where as an individual whose deltoids smaller you could have just a little
bit of an indication of where that attachment was so the deltoid tuberosity there okay moving
distally there's two areas I want you to note here you're going to have a medial epicondyle and
a lateral epicondyle and as you can see this medial epicondyle is quite a bit more robust
or noticeable and that's because you're gonna have the muscles in your forearm on the anterior side
associated with flexion they're all attaching here the superficial group is and if you think about it
that movement of flexing is going to have a bit more forceful contraction so you're gonna have
a larger projection here whereas the lateral epicondyle are where your extensor muscles of
the forearm are going to attach now one thing I want everyone to touch so if they're palpating
right here you can feel a bump right next to your elbow joint that's where this is right here and
your ulnar nerve is going to travel right in this region now how many people have hit their funny
bone that's what's happening you're hitting right here you're hitting your ulnar nerve and causing
that reaction or that feeling of hitting your funny bone so you can actually feel if you go
hard enough you can feel your ulnar nerve which is traveling right there all right this region
right here you can see it's very smooth anytime you have a smooth surface on the bone typically
means that it's articulating or joining with another bone so where we had the formation of
joints you're gonna have your capitulum right here and the trochlea right here the capitulum
is going to articulate with the lateral radius of the forearm whereas the trochlea is going
to articulate with the medial ulna of the forearm when you're looking posteriorly at this olecranon
fossa this is where the olecranon process of the ulna is going to sit during full extension