 Good day, everybody. Good day, everybody. This is Dr. Sanjay Sanyal, Professor of Department Chair. This is going to be a demonstration of the muscles of the flexor compartment of the right forearm. So this is supine cadver. I'm standing on the right side. I'm holding the camera. So the best place to start will be from the cubital fossa itself. So this is the cubital fossa, which we have widely opened out. So let's take a look at the muscle on the lateral aspect. This muscle that we see, this is the brachioraedialis muscle. Brachioraedialis has zero, it takes origin from just above the lateral epicondyle, the lateral supramandala ridge. And it also takes origin from just below that. And here we can see there are two bundles of muscle fibres. This cadver has got a few electrical variations. And the muscle fibres, they converge downwards and they form the lateral boundary of the cubital fossa. And under cover of this muscle, we can see this nerve here. This is the radial nerve. We shall talk more about it later. The fibres then they become aponeurotic and we can see it gets inserted in this particular cadver by means of two bundles. They get inserted by means of a flat, thin aponeurotic sheet onto just above the radial standard process. And passing under cover of the brachioraedialis was this artery also, apart from the superficial branch of the radial nerve, this is the radial artery. And we can see the superficial branch of the radial nerve is emerging from between the two fibres of the brachioraedialis here. And then it will go to the dorsum of the hand. This brachioraedialis reflex can be elicited by tapping with a reflex hammer just above the standard process of the radius. Plastic surgeons use this brachioraedialis for mycutaneous flat surgery. They use it on a vascularized pedicle composed of this radial artery. Now let's come to the next muscle just under that. We can see this muscle here. This is supinator muscle. The supinator muscle, it takes origin from the supinator crest and it curves around the lateral aspect of the radius and gets inserted onto a v-shaped area above the anterior and posterior oblique lines of the radius. So this is the supinator and it forms part of the flow of the cubital fossa. And we can see that the supinator is pierced by this nerve here. This is the deep branch of the radial nerve and it divides the supinator into a superficial and a deep part. And rarely, supinator entrapments in drone can occur when this nerve can get entrapped between the two levels of the supinator muscle. Now let's take a look at the superficial muscles of the flexor compartment. As we know, the flexor compartment has got muscles divided into three layers. Layer one, two and three. The best way to remember is by starting with this muscle here, this is the pronator tibis. The pronator tibis has also got two heads. One head is the humeral head which takes origin from the common flexor origin. And then there's an ulnar head which takes origin from the ulnar just below that. And the two heads then unite and they form the pronator tibis muscle which gets inserted onto the pronator impression on the lateral aspect of the radius. And this forms the intermediate boundary of the cubital fossa. And we can see that piercing through the two heads of the pronator tibis is this nerve here. This is the median nerve. And again, the median nerve can get entrapped with the two heads of the pronator tibis and can produce what is known as the pronator syndrome. Which will produce pain in the flow of the cubital fossa and it will also produce numbness, tingling and peristicia on the distal distribution of the median nerve when we do the stress test. This is the first muscle of the superficial layer P. The next muscle of the superficial layer is this, F. This is flexor carbide radialis which takes origin from the common flexor origin and the fiber becomes steadiness. It does not pass through the carpal tunnel. Instead it passes through a separate tunnel, FCR tunnel in the trapezoid bone, trapezium bone. And then it gets inserted onto the base of the second metacarpal bone. Then we have the next muscle. This is this tendon here. This is the pomerous longus. Pomerous longus tendon has got a very long tendon which does not serve much purpose. It gets inserted onto the flexor reticular. This pomerous longus tendon is used for tendon transplant and it is also used to repair any ligament injury like for example, Wendel. All the collateral ligament of the elbow joint is injured in baseball players. This procedure called the Tommy John procedure where this tendon is used to repair the toe ulnar collateral ligament. And the next muscle is this one here. This is the flexor carbide ulnaris. This flexor carbide ulnaris, as it takes origin from the medial pecan nerve, it gives an aponeurotic expansion which gets attached to the ulnar. And therefore it forms a tunnel which is known as the cubital tunnel. And passing through the cubital tunnel and subsequently under cover of the flexor carbide ulnaris is the snag here. This is the ulnar nerve. So therefore the ulnar nerve can get entrapped in the cubital tunnel. Accompanying the ulnar nerve is the ulnar artery which is located just flat to that. And the flexor carbide ulnaris tendon gets inserted onto the bicep bone which is considered as a sesame bone. And an extension of that goes to the first fifth metacarpal which is the bisopetacarpal ligament. So these are the four muscles in the level, layer number one of the flexor compartment. Now let's lift this up and show the next muscle under that. That is this muscle here. This is the flexor digitalum superficialis. Flexor digitalum superficialis, it is also got two heads, a humeral ulnar head and a radial head. And you can see the radial head when I lift this up here. The radial head takes origin from the anterior oblique line of the radius. And again passing between the two heads of the flexor digitalum superficialis we have the same medial nerve. Which can theoretically can get entrapped here also. The flexor digitalum superficialis tendon it again brings up into four tendons. Which go through the carpal tunnel and it gets inserted onto the middle phalanx of the medial four digits. So therefore they can flex only up to the middle digit. This is the layer number two. When I reflect this layer number two then we see the next muscle. The three muscles in the deep layer and that can be best seen when we reflect this. This is the next muscle. This is the flexor digitalum profundus. The flexor digital profundus takes origin from the anterior surface of the ulnar. And the fibres they also break away to four tendons. Which go through the carpal tunnel and get inserted onto the distal phalanx. Each of these tendons they pierce through a bifid slip of the flexor digitalum superficialis. Along with this flexor digitalum profundus we have this other muscle here. This one. This is the flexor polisius lumbus. Which takes origin from the anterior surface of the radius below the anterior oblique line of the radius. And this flexor polisius lumbus also passes through the carpal tunnel. And each of these tendons by the way also are enclosed in the saligal sheet. And then it gets inserted onto the distal phalanx of the thumb. And the final muscle with the deep compartment is this one here. This is the pronator quadratus. And you can see the pronator quadratus very clearly here. It takes origin from the pronator crest of the ulnar. The fibres they get inserted onto the anterior surface of the lower part of the radius. It is shaped like a quadrangle. That's why it's called pronator quadratus. And this is the pronator tedis in pronation of the arm. That brings me to an important clinical point here. My finger is moving across the space. And we can see that space is bounded posteriorly by the pronator quadratus. Anteriorly it is bounded by the flexor digital profundus. And by the flexor polisius lumbus. This space. Laterally it is bounded by the facial attachment to the radius. Immediately it is bounded by the facial attachment to the ulnar. And superiorly it is bounded by the origin of the flexor polisius lumbus. And the flexor digital profundus from the anterior aspects of the radius. And the ulnar respectively. So this whole space is referred to as the space of parona. This space of parona is a potential space which can be a source of collection of infected material or pus. Which can travel from the mid-former space through the carpal tunnel into the space of parona. So this is the space of parona. So these are the muscles in the flexor compartment of the arm. Namely the leg number one PFBF, leg number two FTS, leg number three. The flexor polisius lumbus is PL, PQ prunetal quadratus and flexor digital profundus. Thank you very much for watching. Dr. Sanjay Sanyal signing out. If you have any questions or comments please put them in the comment section below. Please like and subscribe. Have a nice day.