Hello anatomy colleagues this is Dr Alsup and in this video we will be discussing the
oddly named region referred to as the anatomical snuff box. So first we will actually locate it and
identify those main tendoness boundaries and then of course we'll discuss the contents and
those clinical considerations and why we need to consider this area.
So the anatomical snuff box is a depression in the posterior posterolateral side of the
wrist and it's most noticeable when you extend your thumb or to kind of jut it out laterally,
often referred to as a hitchhiker's thumb.
Now I think we need to address the name. First off if there was another name for this region I
would most certainly use it or if it was commonly used but this is what you hear this referred to as.
Very occasionally you hear the term radial fossa but this is really not caught on maybe we can make
that happen. But it's named this because in this depression in the past individuals will would
hold snuff, which is a kind of ground-up tobacco, before inhaling it in the nose hence the name
snuffbox. Not a very typical practice nowadays but yet the name persists.
So enough about the name let's talk about the actual anatomy. This is going to be formed by
long tendons of the first digit on the posterior side so the tendon of the extensor pollicis longus
or your EPL will form the medial border this is usually the easiest one to see,
you can see it has this kind of ridge and then the lateral border is formed by tendons
the EPB or the extensor pollicis brevis and your abductor pollicis longus
is usually a little bit deeper so you can usually see the EPB a little bit better.
Don't worry so much about remembering which one is which in terms of the tendon names but I do want
you to understand that these are long pollicis or first digit tendons. The floor of the snuff box
which can can be palpated are two carpal bones: the scaphoid which we'll talk a little bit more
about in a moment and the trapezium so both on the lateral side of the carpal bones. You can also
palpate the styloid process of the radius and the proximal portion of this region on deep palpation.
Now what is in this region, what are the contents? Well arguably the most important
is the radial artery I'm going to put a few fun stars next to it so you know that it's important.
So you can actual so this is going to lie in the floor of the snuff box
and you can even feel the radial pulse here but it isn't the most common location to
get a radial pulse because it is a little deep, more common places where the radial artery lies
on the anterior surface of the distal radius, so kind of just lateral to the tendon of
the flexor carpi radialis. So here the artery is really only covered by skin and fascia so a
little bit easier to palpate but you certainly can feel it within the anatomical snuff box as well.
There are some other contents that I will mention but won't you won't hold you accountable for
which includes a cutaneous branch of the radial nerve which is going to end up serving some of
the skin of the hand and even the cephalic vein may pass superficially over this region.
Now before we finish I want to focus on one of the bones that forms the floor of the anatomical snuff
box, the scaphoid, which is the most commonly fractured carpal bone. This fracture similar
to a colace fracture is often caused by a fall on an outstretched hand or foosh love to say
don't love to do, or of course direct trauma can cause this but that's a bit rarer. The fracture
most commonly occurs on this narrowest portion of the bone and this is important it's often not
picked up on initial imaging say right after the injury and it can be misdiagnosed as a severely
sprained wrist so it's difficult to see the fracture sometimes, but imaging done 10 to 14 days
after the injury typically reveals the fracture because bone resorption occurs due to
avascular necrosis. This bone has a very tenuous blood supply in fact it has retrograde blood flow
which we will discuss in more detail in the clinical and anatomical correlation session.
This can cause degenerative joint disease in the wrist as a scaphoid is an important part of the
radiocarpal joint so it's going to be one of those main bones articulating with the distal radius.
Excellent we have reached the summary slide with our big picture concepts regarding the anatomical
snuff box. Please take time to review and always feel free to reach out with any questions
to myself of course or any of my anatomy colleagues. Thank you for your time and attention