Hello, in this video we're going to look at the clinical anatomy of the hand and also the fingers. So we'll actually focus on the wrist joint mainly. Now, we'll begin by focusing on the right hand. And here is the right hand. We're looking at it from a palmar view. So the palms of your hands. And actually the surface anatomy here, you can actually feel. your scaphoid bone, the tubercle of your scaphoid bone. And there's also the piriformis bone you can feel as well as above it the hook of hamate somewhere. Let's look at the right hand again and introduce some of the bones now. Here are the forearm bones, the ulna medially and the radius laterally. You can remember the radius is lateral because lateral is where you can feel the radial artery. The wrist bones consist of many small bones. To put it simply, there are eight. Four sitting on the top and four below. They are collectively known as the carpal bones. You can remember the eight carpal bones by starting at the thumb and moving around in a clockwise motion and remember this saying, So long to Pinky, here comes the thumb. So, S is for scaphoid, L for lunate, T for triquantrum, P for pisiform. Moving up, H is for hamate, C for capitate, and then trapezoid, and then trapezium. So again, so long to pinky, here comes the thumb. The bones of the hands are made up of metacarpals. Then you have the phalanges, and then you have the, of course, the distal, middle, and proximal phalanges, which are the fingers, essentially. But remember the thumb has a metacarpal, but it has a proximal and then a distal phalanges, so there's no middle phalanges. Drawing this same right hand diagram again, looking at it from a palmar view, and imagine cutting a slice through these two sections at the carpal bones. So again we are basically looking at the four carpal bones on the top, or the distal four, and then the other proximal four carpal bones. So focusing on the distal four carpal bones, from the pinky, here comes the thumb. So H is for hamate, C for capitate, T for trapezoid, and then trapezium. Trapezoid and trapezium might be confusing because they sound similar, but to remember which one comes first, think of the last letter of each word. So the D is before the M, and so trapezoid is first, and then it's trapezium, which is closest to the thumb. The hamate has a hook, and travelling across the hamate and the trapezium is the flexor retinaculum. The flexor retinaculum is a very important structure to remember. First let's look at the other proximal four carpal bones. So long to pinky. S is for scaphoid, L for lunate, T triquetrum, and P pisiform. The scaphoid has a tubercle that can be felt. And here again is the flexor retinaculum. The flexor retinaculum is an important part of the hand's anatomy, the wrist anatomy, because things run over it and things run under it. So let's have a closer look and let's stick with the right hand for now. But before going on, I want to introduce to you a tendon, a tendon that runs over your flexor retinaculum called the tendon of Palmaris longus. This tendon is a big tendon you can see in the middle of your wrist and this tendon it originates essentially from the medial epicondyle and is responsible for flexing the wrist. It is innervated by the median nerve. So here I'm drawing the cobble bones of the right hand. Let us now look at things that run superficial to the flexor retinaculum and things that run deep to the flexor retinaculum. Let's begin by looking at the deep structures. And there are many structures that run deep to the flexor retinaculum. It's easy to divide it into four things. One the median nerve. Two the tendons of flexor digitorum superficialis. 3. The tendons of flexor digitorum profundus. 4. The tendon of flexor pollicis longus, which goes to the thumb. The flexor digitorum superficialis and flexor digitorum profundus has 4 actual tendons each. I actually drew this wrong. The tendon of flexor pollicis longus should be at the right hand side because that's the side of the thumb. Sorry. Anyways let's now look and talk about the structures which run superficial to the flexor retinaculum. I just want to add the hook of hamate here and the trapezium here. Again these are the distal carpal bones. Okay, so the structures that run superficial to the flexor retinaculum include the tendon of palmaris longus, which I talked about. Because we are looking at the right hand, the ulnar structures are on the left side, medially. So here is the ulnar artery and the ulnar nerve. Palmar cutaneous branch of the ulnar nerve. And the palmar cutaneous branch of the median nerve can also be found on the other side. Okay, some clinical relevance of the flexor retinaculum and the median nerve. So here is the right hand again. Here is the flexor retinaculum. It's also sometimes referred to as the carpal ligament, which makes sense because it literally goes over the carpal bones. Anyway, remember the four main groups of structures that run under it, one of which is the median nerve. The median nerve is sensory for the middle, index, and thumb region, and also motor for these regions as well. Carpal tunnel syndrome is where you get compression of the median nerve at the flexor retinaculum, causing numbness, paresthesia, and pain in the median nerve distribution. Carpal tunnel syndrome affects females more than men. And there are many causes that actually can cause carpal tunnel and irritate the median nerve. Going back to the diagram we drew earlier, do you remember the tendon of palmaris longus? The tendon that goes over your flexor retinaculum, the tendon you can see on your wrist. Well, this tendon, it has some branches that come off it and form what's called the aponeurosis, the palmar aponeurosis, and this has some clinical relevance. Another clinical relevance is Dupuytren's contracture, which is localized thickening and contracture of the palmar aponeurosis. It causes the proximal and middle phalanx, or phalanges, to flex. The distal phalanx is unaffected. Let's look in more detail at the anatomy of the finger, the phalanges. So here we are mainly looking at either the middle, index, or pinky, or ring finger. But we're not looking at the thumb, because the thumb does not have a middle phalanx. And these other fingers, they consist of the distal phalanx, the middle phalanx, and the proximal phalanx. And then you have your metacarpal. Now, remember the tendons that run under the flexor retinaculum? Well this is where we talk about some of those tendons and where they attach on the finger. See the flexor digitorum superficialis tendons run towards the proximal phalanges, then bifurcates and attaches to the middle phalanx. And so we can say that the flexor digitorum superficialis tendon flexes the proximal interphalangeal joint. The flexor digitorum profundus tendon run below deep to the flexor digitorum superficialis and attaches to the distal phalanx. It does not bifurcate. Thus, we can say the flexor digitorum profundus tendon flexes the distal interphalangeal joint. Alright, some clinical anatomy. Trigger finger is a condition where there is localized thickening of long flexor tendons, which then prevent movement of the tendon within the fibrous sheath. So just think about it as part of the flexor tendon thickening, creating a lump which prevents movement of the finger. So let's just draw it out. Here is a finger, like your index finger. Here are your phalanges, and proximally is your metacarpal bones. Sorry, I know I wrote metatarsal. Tarsals are in your foot. This is meant to be metacarpal. Now in this diagram, it's also important to know that we have these fibrous sheaths sort of running on your... palmar surface of your fingers. And these fibrous sheaths, they sort of act as a pulley. And under it is the flexor tendon. So the flexor tendon runs under the fibrous sheath. A trigger finger is essentially where you have sort of a nodule or thickening of the the flexor tendon that runs under the fibrous sheath and this causes a sort of restrictive movement of that finger. In this case the flexor tendon thickening or nodule is occurring in between the metacarpal bone and the proximal phalanx. This inhibits the flexion between the metacarpal and proximal interphalangeal joint.