hello anatomy friends this is dr alsup and welcome to station number three
where we are talking forearm bone so the ulna and the radius so looking at kind of a complete
view of the upper limb you can see the humerus here which of course is going to be the most
proximal and then we're into the forearm and i want to note that you can see the radius
if this is going to be more medial because you can see the thorax here and this will be more
lateral the radius is always going to be the lateral bone and the ulna will always be
the medial bone and you can see in this particular view we are looking at anatomical
position so there's no crossing over of the radius on the ulna like you would have with a
pronation you can see that the ulna is going to be more complex proximally and larger whereas
the radius will be its larger end will be the more distal end because that makes sense
because it's going to be the major bone in terms of articulating with the carpal bones
so let's start with the more medial bone the ulna as we mentioned the proximal portion of the ulna
is going to be considerably more complex and the distal end will be much smaller and it's not going
to actually make its way all the way to the carpal bones and we're looking at a lateral view here and
the reason i know that is because i can see this structure right here this nice smooth area and
this is going to be the radial notch the radial notch is going to allow um for the periphery
of the radial head to articulate and remember the radial head or the radius is always lateral so if
you have that radial notch facing you in a certain view you know you're looking at a lateral view
so that's the radial notch this right here is going to be the olecranon or the olecranon process
this is going to always project approximately this is that point of the elbow that you can
very easily palpate when on the back of your own elbow so that that robust region right there
you're going to have that triceps brachii muscle tendon attaching here for its distal attachment
this region right here the smooth area is going to be the trochlear notch the trochlear notch
is what is gripping that trochlea of the humerus so really what's articulating with the trochlea
playing a huge role in terms of the humeral ulnar joint and then this projection right here is the
coronoid process so whereas that olecranon is going to be projecting posteriorly the coronoid
process is projecting anteriorly and it's kind of the end of the trochlear notch right here
you're going to have the brachialis muscle attaching here and it will continue to attach
a little bit distal to the coronoid process as well and then again there's that radial notch
for articulation with the periphery of the head of the radius so quite a bit going on in this
proximal portion then you see that the shaft or the body of the ulna gets progressively smaller
and thinner and then you have a little bit of an increase in size on the distal end this is
going to be the head of the ulna and you do have a styloid process associated with
the ulna this is going to be posteriorly facing on the same side as the olecranon
okay now looking at the radius you see the proximal end
up here and the distal end down here you can see increasing in size when you get to the distal end
we're actually looking at a straight anterior view
and then you have this very distinct head of the radius the head unlike with the ulna they'll not
recall the head of the ulna is going to be distal the head of the radius is going to be proximal
and it has this very kind of button-like shape it superior portion which you can't really see here
is smooth as well because that's what's actually articulating with the capitulum of the humerus
and then this periphery of the head is going to rotate around that radial notch of the ulna
then we move this region right here here will be the neck so anytime you have a head you typically
will have a neck that is just distal to it and then you have this fairly robust or large radial
tuberosity and the radial tuberosity is going to be distal to the neck as i mentioned but also it's
going to be important as the distal attachment point for the biceps brachii so those two heads
of the biceps brachii will have a common tendon that will attach here at the radial tuberosity
okay moving to the distal end you are going to have a ulnar notch which is right around this
region right here and it's on the same side as that radial tuberosity it will be facing medially
because if it's a ulnar notch and articulating with the ulna it needs to be facing immediately
almost medial and this is going to accommodate that head of the ulna this small head of the
ulna here and lastly you have a more prominent styloid process associated with the radius this is
going to be laterally facing so opposite the ulnar notch ulnar notch will always be medial and so
the styloid process is fairly prominent you see that it actually is going to project even more
distally than this inferior portion here which is going to articulate with that proximal row
of the carpal bones so the styloid process will actually project kind of into that region there
all right excellent so those are the bones of the forearm take your time to review and kind
of go back to this image here and make sure you have an understanding of how they're organized
in anatomical position and articulating with one another
thank you for your time and attention here and always feel free to reach out with any questions