 In this video, I will identify the appendicular muscles that move the manual region and list the origin, insertion, and action of major muscles that move the manual region. We'll start with a posterior view, getting oriented to the muscles that extend the manual region. Extensor Carpi Radialis Longus is found immediately on the medial side of brachioradialis. They share an origin at the lateral supercondular ridge of the humerus. But the action of extensor Carpi Radialis Longus is in the name. So extensor Carpi, this is a muscle that performs the action of extension of the radiocarpal joint. Similarly, extensor Carpi Radialis Brevis performs the action of extension at the radiocarpal joint. So these muscles extend the wrist, extend the radiocarpal joint, and most of the muscles located on the posterior anti-brickial region are extensor muscles that perform either extension of the radiocarpal joint or extension of the digits. So if we move medially from extensor Carpi Radialis Brevis, the next muscle we see is extensor digitorum. And again, the name tells us the action. Extensor digitorum performs the action of extension of the manual digits, extension of the fingers. Extensor Digiti Minimai is just medial to extensor digitorum. This is a slender muscle that inserts into the fifth digit into the phalanges of the fifth digit in order to extend the fifth digit, to extend the smallest finger, the pinky finger. Then medial to extensor digiti minimai, the most medial of the extensor muscles on the posterior anti-brickial region, is extensor Carpi Ulnaris. So you'll remember that the ulna is the medial anti-brickial bone, whereas the radius is the lateral anti-brickial bone. Extensor Carpi Ulnaris is an extensor, so it's on the posterior anti-brickial region, and it's ulnaris. It's found superficial to the ulna on the medial side, and the action of this muscle is again in the name. Extensor Carpi Ulnaris performs the action of extension of the radiocarpal joints. So a few other muscles that we can see in this illustration include Abductor Policis Longus, that performs the action of abduction of the Pollux, abduction of the largest digit, the first digit, the thumb. So Abductor Policis Longus abducks the Pollux. Extensor Policis Longus performs extension of the Pollux. And similarly, Extensor Policis Longus performs extension of the Pollux. In this illustration, all we can see is the tendon from Extensor Policis Longus, because the belly of the muscle is located deep to Extensor Digitorum. Now we'll go through more detail for the major muscle, starting with Extensor Carpi Radialis Longus, that has its origin from the humerus at the lateral supracondylar ridge, the same place that is the origin for brachioradialis. Then the insertion for Extensor Carpi Radialis is the second metacarpal. So you can see the tendon coming down to insert here at the second metacarpal. And the action is in the name to extend the radiocarpal joint. Extensor Carpi Radialis Brevis has its origin from the lateral epicondyle of the humerus, and its insertion onto the third metacarpal to perform the action of extension at the radiocarpal joint. Extensor Digitorum also has its origin from the lateral epicondyle of the humerus, and its insertion is onto the distal phalanges of digits 2 through 5, and the action of Extensor Digitorum is in the name its extension of the manual digits. Similarly the origin of Extensor Carpi Ulnaris is from the lateral epicondyle of the humerus, and so we've seen now the origin from the lateral epicondyle of the humerus is shared for Extensor Carpi Radialis Brevis, Extensor Digitorum, and Extensor Carpi Ulnaris. The insertion for Extensor Carpi Ulnaris is the fifth metacarpal, and the action is to extend the radiocarpal joint. Now here we have a deep view of the posterior anti-brachial region with the superficial muscles that we've just covered removed. So brachioradialis, Extensor Carpi Radialis Longus, and Extensor Carpi Radialis Brevis, Extensor Digitorum, and Extensor Carpi Ulnaris have all been removed to give us this view, and the major muscle that's located on the lateral posterior anti-brachial region, deep under brachioradialis and Extensor Carpi Radialis Longus and Brevis, is the supinator, and so the supinator is another muscle with its action in the name. The supinator performs supination of the proximal radio ulnar joint. Now another muscle that we can see better with this deep view is Extensor Policis Longus. We were able to see the tendon of Extensor Policis Longus coming out to its insertion from a superficial view, but now with Extensor Digitorum removed we can see the belly of Extensor Policis Longus, which is located just medial to Extensor Policis Brevis. Now the origin of the supinator is from the lateral epicondyle of the humerus, and if a muscle is going to perform supination or pronation of the proximal radio ulnar joint, that muscle will have to have its insertion on the radius, and so the insertion for the supinator is the radius, and the action is supination of the proximal radio ulnar joint. Now here we have a superficial view of the anterior anti-brachial region. We will start going through from the lateral side with pronator teres, a muscle that has its action in the name pronation of the proximal radio ulnar joint is the action of pronator teres. Next moving medially across the anti-brachial region we see flexor carpi radialis. Another muscle with its action in the name flexor carpi radialis performs flexion of the radiocarpal joint. Pulmeris longus is located just medial to flexor carpi radialis. Pulmeris longus does assist with the action of flexion of the radiocarpal joint. Pulmeris longus is a variable muscle that is absent and are about 10% of humans. Then located just medial to pulmeris longus is flexor carpi ulnaris, a muscle that performs the action of flexion of the radiocarpal joint. So flexion of the hand at the wrist, flexion of the manual region at the radiocarpal joint. So you'll notice a pattern with the first letter of those muscles. Pronator teres is P, flexor carpi radialis is F, and then pulmeris longus begins with P and flexor carpi ulnaris begins with an F. And so a mnemonic memory device that can help you remember those order, the order of those muscles PF, PF could stand for pass fail, pass fail, or if you'd like to end on a good note you could start from the medial side and work your way towards the lateral side with fail pass, fail pass. Those are the four superficial muscles on the anterior and to brachial region. There's one muscle located deep to those four superficial muscles that we can see in between the tendons of those muscles. This is flexor digitorum superficialis. So as the name tells us superficialis, this muscle is still superficial to another muscle, another flexor digitorum. Flexor digitorum profundus is deep to flexor digitorum superficialis. And there's three muscles in the anterior and to brachial region located deep to flexor digitorum superficialis. So that gives us four muscles in the most superficial layer, one muscle in the intermediate layer flexor digitorum superficialis, and then three muscles that are deep to flexor digitorum superficialis. And so it might help you to remember that orientation with there's four, and it's that four, four superficial, then one flexor digitorum superficialis, the intermediate, and then what's left, three that are deep to flexor digitorum superficialis. We'll start going through with more detail to meet your muscles here. The pronator teres has its origin from the medial epicondyle of the humerus. And we'll see that most of the muscles found on the anterior of the anterbrachial region have their origin from the medial epicondyle of the humerus. Now the action of pronator teres is pronation, so its insertion is the radius. A flexor carbiradialis also has its origin from the medial epicondyle of the humerus and inserts onto the second and third metacarpals to perform the action of flexion at the radiocarpal joint. Flexor carbiradialis has its origin also from the medial epicondyle of the humerus. The insertion of flexor carbiradialis is the fifth metacarpal, the hook of the handmaid, and the piezoform. The action is in the name to flex the radiocarpal joint. The origin of flexor digitorum superficialis is also from the medial epicondyle of the humerus and the insertion of flexor digitorum superficialis is the middle phalanges two through five. The action is to flex the manual digits. Here we have a deep view of the anterior and to brachial region. The pronator teres, flexor carbiradialis, pulmaris longus, flexor carbirulmaris, and flexor digitorum superficialis have all been removed to give us this view of the three muscles located deep to flexor digitorum superficialis. We can see flexor digitorum profundus. The name profundus translates to deep. So flexor digitorum profundus is located deep to flexor digitorum superficialis and performs the action of flexion of the manual digits. The two other muscles located in this deep group of anter brachial muscles include flexor pulisus longus, a muscle that performs flexion of the polyx, and pronator quadratus, a rectangular shaped muscle found in the distal anter brachial region deep to the tendons of flexor digitorum profundus. And the action of pronator quadratus is pronation of the proximal radio ulnar joint. The origin of flexor digitorum profundus is on the ulna at the coronoid process of the ulna. Then the insertion of flexor digitorum profundus is onto the distal phalanges digits 2 through 5. And the action of flexor digitorum profundus is in the name to flex the manual digits. Flexor digitorum profundus is the deep muscle that performs flexion of the manual digits.