Resumen de los Músculos del Miembro Superior

Hello, Hello, my dear colleagues. my dear colleagues. Today I bring you a video about the anatomy of the muscles of the upper limb. Today I bring you a video about the anatomy of the muscles of the upper limb. More specifically, More specifically, we will talk about the anatomy of the muscles of the shoulder and pectoral regions. we will talk about the anatomy of the muscles of the shoulder and pectoral regions. Before starting this video, Before starting this video, I invite you to subscribe to my channel. I invite you to subscribe to my channel. Here in the lower right corner, Here in the lower right corner, you will find a link that, you will find a link that, if you click on it, if you click on it, you will be subscribed to the channel and can access more content. you will be subscribed to the channel and can access more content. Before starting, Before starting, I will put the cursor here again, I will put the cursor here again, because I always forget to put it here. because I always forget to put it here. Very well, Very well, we already have the pointer ready. we already have the pointer ready. So, So, well, well, let's divide this class into three muscle groups. let's divide this class into three muscle groups. The first muscle group that we will talk about are the muscles found in the pectoral region, The first muscle group that we will talk about are the muscles found in the pectoral region, which are four. which are four. We will talk about the pectoralis major and minor, We will talk about the pectoralis major and minor, the suclavius muscle, the suclavius muscle, and the serratus anterior muscle. and the serratus anterior muscle. Although these are muscles found in a region that is practically thoracic. Although these are muscles found in a region that is practically thoracic. Their function is towards the upper limb and that is why they are studied as muscles of the upper limb. Their function is towards the upper limb and that is why they are studied as muscles of the upper limb. Then we will talk about the superficial muscles of the back, Then we will talk about the superficial muscles of the back, which are the same. which are the same. They are muscles located in the back of the chest, They are muscles located in the back of the chest, but their function is to move the upper limb. but their function is to move the upper limb. Here we will talk about five muscles, Here we will talk about five muscles, the trapezius, the trapezius, the latissimus dorsi, the latissimus dorsi, the scapulae angle, the scapulae angle, and the rhomboids. and the rhomboids. And finally, And finally, we will talk about the muscles of the shoulder region, we will talk about the muscles of the shoulder region, which are six. which are six. They are the ones that start the upper limb itself, They are the ones that start the upper limb itself, which are the deltoid, which are the deltoid, the subscapularis, the subscapularis, the supraspinatus, the supraspinatus, and the infraspinatus, and the infraspinatus, and the teres major and minor. and the teres major and minor. We will quickly begin by explaining what the origin and insertion are. We will quickly begin by explaining what the origin and insertion are. Something basic that you have to learn with each muscle in the human body is that you have to learn to do four fundamental things. Something basic that you have to learn with each muscle in the human body is that you have to learn to do four fundamental things. First, First, the origin, the origin, then the insertion, then the insertion, then the innervation, then the innervation, that is, that is, which nerve makes that muscle move. which nerve makes that muscle move. and finally the function. and finally the function. So, So, very often you confuse what the origin and insertion are, very often you confuse what the origin and insertion are, and they are not the same. and they are not the same. In fact, In fact, it is a little trick. it is a little trick. If you learn the difference between origin and insertion, If you learn the difference between origin and insertion, basically by learning only the origin, basically by learning only the origin, insertion, insertion, and direction of a muscle, and direction of a muscle, you can infer what the function of that muscle is. you can infer what the function of that muscle is. Let me explain. Let me explain. Every muscle has two roots, Every muscle has two roots, two ends. two ends. One is the origin and the other is the insertion. One is the origin and the other is the insertion. Many authors call the origin a fixed insertion and the insertion a mobile insertion. Many authors call the origin a fixed insertion and the insertion a mobile insertion. What does this mean? What does this mean? The origin is the part of the muscle that does not move. The origin is the part of the muscle that does not move. That is, That is, it is the fixed part of the muscle, it is the fixed part of the muscle, which is why they call it a fixed insertion, which is why they call it a fixed insertion, while the part of the muscle that is going to move, while the part of the muscle that is going to move, that is, that is, the part that is going to be cut, the part that is going to be cut, the part that shrinks, the part that shrinks, is the insertion. is the insertion. And that is why they call it a mobile insertion. And that is why they call it a mobile insertion. Here the example is with the vice brachialis. Here the example is with the vice brachialis. its fixed portion. its fixed portion. Its origin is at the level of the coracoid process and the scapula. Its origin is at the level of the coracoid process and the scapula. That is the part of the muscle that does not move. That is the part of the muscle that does not move. So, So, its insertion is going to be at the radial level. its insertion is going to be at the radial level. That's why when it contracts, That's why when it contracts, it doesn't just grab the radius to move my scapula, it doesn't just grab the radius to move my scapula, because I'm explaining to him that the scapula is the origin. because I'm explaining to him that the scapula is the origin. It's going to grab the scapula, It's going to grab the scapula, which is its origin, which is its origin, to perform its function in the insertion, to perform its function in the insertion, which is to move the radius and thus flex my forearm. which is to move the radius and thus flex my forearm. So, So, it's very important that you fix these two things. it's very important that you fix these two things. We're going to see it during the video, We're going to see it during the video, because this mnemonic is very easy to learn the origin and insertion, because this mnemonic is very easy to learn the origin and insertion, as well as their differences. as well as their differences. So, So, let's start first with the muscles of the pectoral region. let's start first with the muscles of the pectoral region. At this level, At this level, we're going to find four muscles. we're going to find four muscles. We're going to go from superficial to deep. We're going to go from superficial to deep. First, First, we'll talk about the pectoralis major muscle. we'll talk about the pectoralis major muscle. As you can see, As you can see, this is a muscle that originates on the lower edge of the clavicle, this is a muscle that originates on the lower edge of the clavicle, on the lateral edge of the sternum, on the lateral edge of the sternum, as well as on the six costal caudal edges that are located posteriorly. as well as on the six coastal caudal edges that are located posteriorly. Many authors also describe its origin as being at the level of what is called the ponorosis of the oblique major muscle, Many authors also describe its origin as being at the level of what is called the ponorosis of the oblique major muscle, also called the external oblique. also called the external oblique. So this muscle moves laterally, So this muscle moves laterally, curves, curves, that is, that is, rolls up, rolls up, and inserts into the vixipital groove of the humerus. and inserts into the vixipital groove of the humerus. If I explain to you that the origin is at this medial level and the insertion is lateral, If I explain to you that the origin is at this medial level and the insertion is lateral, it is not that he is going to grab the number to move my sternum and clavicle, it is not that he is going to grab the number to move my sternum and clavicle, because you already know that this is the origin. because you already know that this is the origin. So, So, he grabs the origin, he grabs the origin, which is the sternum and the clavicle, which is the sternum and the clavicle, to move my arm. to move my arm. And if you look at this image, And if you look at this image, what function do you think the pectoralis major will have? what function do you think the pectoralis major will have? When it contracts, When it contracts, since it is going to contract at the insertion level, since it is going to contract at the insertion level, it moves the arm inwards, it moves the arm inwards, that is, that is, medially. medially. That is why it is an adductor of the arm, That is why it is an adductor of the arm, but in addition to adducting, but in addition to adducting, it also internally rotates the arm. it also internally rotates the arm. So, So, see how easy this neoteny of the origin and insertion is. see how easy this neoteny of the origin and insertion is. Here you can see how the tendon of the pectoralis major muscle goes in front of the vice versa and is covered by the toid muscle to finally insert into the external lip of the vici-ip-pital groove. Here you can see how the tendon of the pectoralis major muscle goes in front of the vice versa and is covered by the toid muscle to finally insert into the external lip of the vici-ip-pital group. Now, Now, the next muscle is posterior to the pectoralis major. the next muscle is posterior to the pectoralis major. Look at this image here. Look at this image here. On this side, On this side, they section the pectoralis major. they section the pectoralis major. We find this aponeurosis which is the clavipectoral aponeurosis. We find this aponeurosis which is the clavipectoral aponeurosis. And then we section the clavipectoral aponeurosis to find this muscle which is the pectoralis minor muscle. And then we section the clavipectoral aponeurosis to find this muscle which is the pectoralis minor muscle. So it will be found posterior to the pectoralis major. So it will be found posterior to the pectoralis major. This pectoralis minor muscle originates from the second to the fifth rib. This pectoralis minor muscle originates from the second to the fifth rib. Although you see this image of the rib that is from the third to the fifth. Although you see this image of the rib that is from the third to the fifth. Well, Well, the theory says that it is from the second to the fifth. the theory says that it is from the second to the fifth. So, So, I'm giving it to you as the theory says, I'm giving it to you as the theory says, but not as shown in the image, but not as shown in the image, because remember that there are many anatomical variations and we don't know if this cadaver that Netter used for this drawing was one of those anatomical variations. because remember that there are many anatomical variations and we don't know if this cadaver that Netter used for this drawing was one of those anatomical variations. So this pectoralis minor muscle originates from the second and fifth ribs and inserts into the coracoid process of the scapula. So this pectoralis minor muscle originates from the second and fifth ribs and inserts into the coracoid process of the scapula. So, So, it's not like it's going to grab onto the coracoid process to raise my ribs. it's not like it's going to grab onto the coracoid process to raise my ribs. because I'm explaining to you that the origin is down here. because I'm explaining to you that the origin is down here. So, So, its function is going to be to lower the coracoid process. its function is going to be to lower the coracoid process. That's why it's said that its function is to lower the shoulder. That's why it's said that its function is to lower the shoulder. So, So, who supplies the two pectorals? who supplies the two pectorals? The pectoralis major and pectoralis minor nerves, The pectoralis major and pectoralis minor nerves, which are branches of the secondary trunks of the anterolateral and antero-internal brachial plexus. which are branches of the secondary trunks of the anterolateral and antero-internal brachial plexus. It's very important that you watch my video on the brachial plexus. It's very important that you watch my video on the brachial plexus. At the end of this video I will leave you the link so that you can understand where the nerves that move these muscles come from. At the end of this video I will leave you the link so that you can understand where the nerves that move these muscles come from. So, So, we have already covered two of the four. we have already covered two of the four. We talked about the pectoralis major and minor. We talked about the pectoralis major and minor. Now we are going to talk about the subclavius muscle. Now we are going to talk about the subclavius muscle. As its name suggests, As its name suggests, it is located below the clavicle, it is located below the clavicle, which is the clavicle. which is the clavicle. This subclavius muscle originates at the junction of the first rib with the first coastal cartilage and inserts into a canal on the underside of the clavicle. This subclavius muscle originates at the junction of the first rib with the first coastal cartilage and inserts into a canal on the underside of the clavicle. Basically, Basically, its innervation is through the subclavian nerve. its innervation is through the subclavian nerve. which is a nerve that derives from the brachial plexus, which is a nerve that derives from the brachial plexus, specifically from the superior primary trunk. specifically from the superior primary trunk. Its function is to keep this external clavicular joint stable and prevent it from displacing the head of the clavicle from coming out of the clavicular fossa, Its function is to keep this external clavicular joint stable and prevent it from displacing the head of the clavicle from coming out of the clavicular fossa, which is the external sternum. which is the external sternum. That is basically the function of the subclavius muscle. That is basically the function of the subclavius muscle. And finally, And finally, within this muscle, within this muscle, this group of muscles in the pectoral region, this group of muscles in the pectoral region, we are talking about the serratus anterior muscle. we are talking about the serratus anterior muscle. In many books, In many books, you can find it under the name of serratus anterior. you can find it under the name of serratus anterior. It is the same as serratus major and serratus anterior. It is the same as serratus major and serratus anterior, It is called that because it looks like a saw, it is called that because it looks like a saw, a hacksaw. a hacksaw. Its origin is eight digits from the first to the eighth rib. Its origin is 8 digits from the first to the 8th rib. That is its origin. That is its origin. This muscle runs laterally, This muscle runs laterally, goes in front of the scapula to finally insert on the medial edge of the scapula. goes in front of the scapula to finally insert on the medial edge of the scapula. So, So, when it retracts, when it retracts, the scapula basically goes out. the scapula basically goes out. That is why its function is to abduct the arm. That is why its function is to abduct the arm. because when I move the scapula out, because when I move the scapula out, the humerus that is attached to the scapula goes out as well. the humerus that is attached to the scapula goes out as well. That is the abduction movement. That is the abduction movement. The innervation of the serratus major is the nerve of the serratus major, The innervation of the serratus major is the nerve of the serratus major, also called the long thoracic nerve. also called the long thoracic nerve. Very well, Very well, those are the muscles of the pectoral region. those are the muscles of the pectoral region. Let's now move on to the superficial muscles of the back, Let's now move on to the superficial muscles of the back, which are five. which are five. To start with the first of these five, To start with the first of these five, we're going to talk about the trapezius muscle. we're going to talk about the trapezius muscle. It's called that because it's really shaped like a trapezius. It's called that because it's really shaped like a trapezius. It has a very extensive origin. It has a very extensive origin. It's said to originate from the superior curved line of the occiput, It's said to originate from the superior curved line of the occiput, external occipital protuberance, external occipital protuberance, posterior cervical ligament, posterior cervical ligament, also called the nuchal ligament, also called the nuchal ligament, spinous process of S7, spinous process of S7, which is this very prominent one that you see here, which is this very prominent one that you see here, as well as the spinous process of all the thoracic vertebrae without exception. as well as the spinous process of all the thoracic vertebrae without exception. In addition, In addition, it's also said to originate from what is called the supraspinous ligament. it's also said to originate from what is called the supraspinous ligament. So, So, Notice that this entire medial area is the origin. Notice that this entire medial area is the origin. Now, Now, its insertion is going to be on the upper lip of the spine of the scapula. its insertion is going to be on the upper lip of the spine of the scapula. And when I rotate the image, And when I rotate the image, this would be the acromion of the scapula and here the external third of the clavicle. this would be the acromion of the scapula and here the external third of the clavicle. It is then inserted into the spine of the scapula, It is then inserted into the spine of the scapula, the chroma of the scapula, the chroma of the scapula, and the external third of the clavicle, and the external third of the clavicle, innervated by the cervical plexus, innervated by the cervical plexus, that is, that is, C3, C3, C4, C4, plus the trunk of a cranial nerve, plus the trunk of a cranial nerve, which is the 11th cranial nerve. which is the 11th cranial nerve. also called the accessory nerve. also called the accessory nerve. Since its insertion is in the scapula, Since its insertion is in the scapula, its function is going to be in the scapula and that is precisely to rotate and elevate the scapula. its function is going to be in the scapula and that is precisely to rotate and elevate the scapula. Let's move on to the latissimus dorsi muscle. Let's move on to the latissimus dorsi muscle. This muscle has a broad origin. This muscle has a broad origin. It is also said that it is in the last five thoracic vertebrae, It is also said that it is in the last five thoracic vertebrae, that is, that is, from 8 to 12, from 8 to 12, as well as in all the lumbar and sacral vertebrae through this peneurosis that you see here, as well as in all the lumbar and sacral vertebrae through this peneurosis that you see here, which is the famous columbar peneurosis. which is the famous columbar peneurosis. In addition, In addition, it has a fascicle of origin from the iliac crest of the iliac bone. it has a fascicle of origin from the iliac crest of the iliac bone. This muscle is the most superficial of the back, This muscle is the most superficial of the back, along with the trapezius, along with the trapezius, and it goes laterally to insert into the vicissitudes. and it goes laterally to insert in the iliac bone. into the vicissitudes. So its function, So its function, when it contracts, when it contracts, is to reach the vicissitudes precisely here, is to reach the vicissitudes precisely here, so that you understand the anatomical arrangement of this muscle. so that you understand the anatomical arrangement of this muscle. And when it contracts, And when it contracts, the arm basically goes inward, the arm basically goes inward, that is, that is, medially. medially. That is why it is said to be an adductor of the arm. That is why it is said to be an adductor of the arm. Also, Also, since it is a muscle that grips the arm towards the back, since it is a muscle that grips the arm towards the back, when it contracts, when it contracts, it takes the arm posteriorly, it takes the arm posteriorly, which is why it is said to be both an adductor and an extensor of the arm. which is why it is said to be both an adductor and an extensor of the arm. It is innervated basically by the latissimus dorsi nerve, It is innervated basically by the latissimus dorsi nerve, also called the thoracodorsal nerve. also called the thoracodorsal nerve. Look carefully at this image, Look carefully at this image, how it is originating in the lower dorsal vertebrae, how it is originating in the lower dorsal vertebrae, as well as in the lumbar vertebrae. as well as in the lumbar vertebrae. And here you can see the origin of the iliac crest, And here you can see the origin of the iliac crest, the iliac bone. the iliac bone. There are now many books that describe an origin that comes from the lower vertex of the scapula. There are now many books that describe an origin that comes from the lower vertex of the scapula. So it is very important to keep this origin in mind and here you can clearly see how the insertion occurs in the bicipital path. So it is very important to keep this origin in mind and here you can clearly see how the insertion occurs in the bicipital path. So, So, in this diagram you can see that if the muscle contracts, in this diagram you can see that if the muscle contracts, the upper limb goes medially and that is adduction. the upper limb goes medially and that is adduction. Let's now move on to the angle of the scapula. Let's now move on to the angle of the scapula. In most books you will find it under the name of the levator scapulae muscle. In most books you will find it under the name of the levator scapulae muscle. Basically, Basically, with that you already know what the function of this muscle is. with that you already know what the function of this muscle is. It is said that it originates in the transverse processes of the vertebrae from C1 to S4, It is said that it originates in the transverse processes of the vertebrae from C1 to S4, specifically in the posterior tubercles and is inserted into the medial border of the scapula. specifically in the posterior tubercles and is inserted into the medial border of the scapula. Its innervation is by the cervical plexus. Its innervation is by the cervical plexus. that is, that is, the anterior branch of C3-C4 and its function, the anterior branch of C3-C4 and its function, as you know, as you know, if it is called levator scapulae, if it is called levator scapulae, it must basically be to elevate the scapula. it must basically be to elevate the scapula. And then we move on to the rhomboid muscles. And then we move on to the rhomboid muscles. In anatomy, In anatomy, it is very important for you to know that there are many structures that have the names of minor and major. it is very important for you to know that there are many structures that have the names of minor and major. Almost always, Almost always, almost always, almost always, not always, not always, but almost always, but almost always, the minor is on top and the major is on the bottom. the minor is on top and the major is on the bottom. So, So, Basically this muscle that you see on top is the rhomboid minor and this one on the bottom is the rhomboid major. Basically this muscle that you see on top is the rhomboid minor and this one on the bottom is the rhomboid major. Note that its origin is at the level of the spine. Note that its origin is at the level of the spine, Specifically it is the rhomboid minor at the level of the spinous process of C7 and D1. specifically it is the rhomboid minor at the level of the spinous process of C7 and D1, While the rhomboid major is the spinous process from D2 to D5. while the rhomboid major is the spinous process from D2 to D5. So here it is C7 and D1, So here it is C7 and D1. Here it is from D2 to C5 to D5, here it is from D2 to C5 to D5, sorry, sorry. and it inserts into everything that is the medial border of the scapula. And it inserts into everything that is the medial border of the scapula. When these muscles contract, When these muscles contract, the scapula will go medially. the scapula will go medially. That is why you will see in the books that its function is to fix and retract the scapula. That is why you will see in the books that its function is to fix and retract the scapula. The innervation will be basically through the rhomboid nerve, The innervation will be basically through the rhomboid nerve, which is also called the dorsal scapular nerve. which is also called the dorsal scapular nerve. Finally, Finally, we will go over the muscles of the shoulder region, we will go over the muscles of the shoulder region, of which there are six. of which there are six. We will first talk about the most superficial of these muscles of the shoulder region, We will first talk about the most superficial of these muscles of the shoulder region, which is the deltoid, which is the deltoid, which is the one that gives the shoulder its roundness. which is the one that gives the shoulder its roundness. that characteristic shape. that characteristic shape. This deltoid muscle, This deltoid muscle, let's say its origin is where the trapezius inserts. let's say its origin is where the trapezius inserts. Remember that the trapezius inserts into the spine of the scapula, Remember that the trapezius inserts into the spine of the scapula, the chromon of the scapula, the chromon of the scapula, and the lateral third of the clavicle. and the lateral third of the clavicle. The same goes for the deltoid, The same goes for the deltoid, except that the trapezius inserts into the upper edge of these structures and the deltoid originates from the lower edge of these structures. except that the trapezius inserts into the upper edge of these structures and the deltoid originates from the lower edge of these structures. See here in this back image how it is inserting, See here in this back image how it is inserting, originating, originating, sorry. sorry. where the trapezius inserts. where the trapezius inserts. Its insertion is basically in the tuberosity, Its insertion is basically in the tuberosity, also called the deltoid V of the humerus, also called the deltoid V of the humerus, and it has several functions, and it has several functions, but the most important are to adduce and flex the arm, but the most important are to adduce and flex the arm, because when the arm contracts it goes outwards. because when the arm contracts it goes outwards. Its innervation is provided by the axillary nerve, Its innervation is provided by the axillary nerve, also called the circumflex nerve of the brachial plexus. also called the circumflex nerve of the brachial plexus. Now we are going to talk about the spinous muscles. Now we are going to talk about the spinous muscles. Remember that this structure is the spine of the scapula. Remember that this structure is the spine of the scapula. So, So, the muscle that is located above it is the supraspinatus and the one that is basically below it is the infraspinatus. the muscle that is located above it is the supraspinatus and the one that is basically below it is the infraspinatus. In order to access these muscles, In order to access these muscles, we basically have to section both the trapezius and the deltoid. we basically have to section both the trapezius and the deltoid. So this supraspinatus muscle, So this supraspinatus muscle, its origin is going to be in the supraspinous fossa. its origin is going to be in the supraspinous fossa. It is going to pass through the spinoglenoid notch of the scapula and it is going to insert in the greater tuberosity. It is going to pass through the spinoglenoid notch of the scapula and it is going to insert in the greater tuberosity. also called the other tuberosity of the humerus. also called the other tuberosity of the humerus. If it contracts, If it contracts, then the arm will go outwards. then the arm will go outwards. That's why it's said that it's an abductor of the arm and is innervated by the suprascapular nerve. That's why it's said that it's an abductor of the arm and is innervated by the suprascapular nerve. The infraspinatus is easy. The infraspinatus is easy. If the supraspinatus originated in the supraspinatus fossa, If the supraspinatus originated in the supraspinatus fossa, the infraspinatus then originates in the infraspinatus fossa. the infraspinatus then originates in the infraspinatus fossa. Its insertion, Its insertion, like the supraspinatus, like the supraspinatus, that is, that is, in the greater tuberosity of the humerus and its innervation is the same. in the greater tuberosity of the humerus and its innervation is the same. which is by the supraspinatus nerve. which is by the supraspinatus nerve. What changes is the function. What changes is the function. I had told you that the supraspinatus is an abductor of the arm, I had told you that the supraspinatus is an abductor of the arm, while the infraspinatus, while the infraspinatus, which would be this one here, which would be this one here, is an external rotator of the arm. is an external rotator of the arm. When the arm contracts, When the arm contracts, what it does is rotate, What it does is rotate, it turns. it turns. Now let's take a closer look at this image. Now let's take a closer look at this image. This would be the supraspinatus and this one below would be the infraspinatus. This would be the supraspinatus and this one below would be the infraspinatus. See that both are reaching the greater tuberosity. See that both are reaching the greater tuberosity. And in this superior view here we see the spinoglenoid notch, And in this superior view here we see the spinoglenoid notch. How the supraspinatus takes advantage of that gap. how the supraspinatus takes advantage of that gap. And here we see the infraspinatus reaching what is the humeral head. And here we see the infraspinatus reaching what is the humeral head. Now we are going to talk about the subscapularis. Now we are going to talk about the subscapularis. This is an anterior view of the scapula. This is an anterior view of the the scapula. Basically, Basically, what we are seeing up here is the supraspinatus, What we are seeing up here is the supraspinatus, which makes the names, which makes the names, and all this muscle that originates in the subscapular fossa is the famous subscapularis muscle. and all this muscle that originates in the subscapular fossa is the famous subscapularis muscle. That muscle inserts into the lesser tuberosity, That muscle inserts into the lesser tuberosity, also called the humeral tuberosity. also called the humeral tuberosity. So, So, if you imagine that this is the origin, if you imagine that this is the origin, when it contracts at its insertion, when it contracts at its insertion, basically the head of the humerus will rotate, basically the head of the humerus will rotate, but not like the supraspinatus does, but not like the supraspinatus does, which makes it rotate outwards. which makes it rotate outwards, but rather it makes it rotate inwards. but rather it makes it rotate inwards. That's why its function is medial rotation or internal rotation of the arm and its innervation is provided by the superior subscapularis and inferior subscapularis nerves. That's why its function is medial rotation or internal rotation of the arm and its innervation is provided by the superior subscapularis and inferior subscapularis nerves. Here we can see basically how the subscapularis passes behind this muscle which is the cobracobrachialis and behind the short head of the visbrachialis to be able to reach the lesser tuberosity or small bone of the humerus to be able to perform its internal rotation. Here we can see basically how the subscapularis passes behind this muscle which is the cobracobrachialis and behind the short head of the visbrachialis to be able to reach the lesser tuberosity or small bone of the humerus to be able to perform its internal rotation. Here we also see this upper image of the subscapularis muscle below. Here we also see this upper image of the subscapularis muscle below, You know, you know, the infraspinatus, the infraspinatus, below and also anterior. below and also anterior. Now, Now, finally, finally, we are going to talk about the two round muscles, we are going to talk about the two round muscles, which are the teres minor, which are the teres minor, which is the one that is on top. which is the one that is on top. So, So, the one that is below, the one that is below, what should it be called? what should it be called? Very good. Very good. It should be called teres major. It should be called teres major. So, So, do not confuse this one which is the supraspinatus, do not confuse this one which is the supraspinatus, infraspinatus, infraspinatus, sorry, sorry, these three fascicles with this one which is the teres minor and this one that is below, these three fascicles with this one which is the teres minor and this one that is below, which is the teres major. which is the teres major. These muscles have the same origin, These muscles have the same origin. that is, that is, they originate in the infraspinatus fossa, they originate in the infraspinatus fossa. But what changes is their insertion. but what changes is their insertion. Let's look at this image that is much closer. Let's look at this image that is much closer. See that its origin is at the level of the infraspinatus fossa. See that its origin is at the level of the infraspinatus fossa. This is the infraspinatus. This is the infraspinatus. This is the supraspinatus. This is the supraspinatus. This would be the tendon of the infraspinatus. This would be the tendon of the infraspinatus. And this one that is cut here would be the teres minor. And this one that is cut here would be the teres minor. Its origin is in the south scapular fossa and it inserts into what is the greater tuberosity. Its origin is in the south scapular fossa and it inserts into what is the greater tuberosity. Its function is to externally rotate the arm. Its function is to externally rotate the arm. To give you an idea, To give you an idea, The infraspinatus together with the teres minor have the same function, the infraspinatus together with the teres minor have the same function. which is external rotation of the arm. which is external rotation of the arm. Whereas unlike the teres minor, Whereas unlike the teres minor, the teres major, the teres major, which is the one below, which is the one below, which is this one, which is this one, is inserted into the viscipital groove, is inserted into the viscipital groove, specifically on the internal side, specifically on the internal side, and its function is to move the arm medially. and its function is to move the arm medially. That is why it is an adductor of the arm, That is why it is an adductor of the arm, it has nothing to do with rotation. it has nothing to do with rotation. This teres major is innervated by the inferior subscapular nerve. This teres major is innervated by the inferior subscapular nerve, while the teres minor is innervated by the circumflex nerve, while the teres minor is innervated by the circumflex nerve, which is the axillary nerve. which is the axillary nerve. Now, Now, in the next video that you are going to watch, In the next video that you are going to watch, we are going to talk about what the rotator cuff is, we are going to talk about what the rotator cuff is, which is a muscle tendon structure formed by four muscles. which is a muscle tendon structure formed by four muscles. We have already seen those four muscles, We have already seen those four muscles, which are precisely the supraspinatus, which are precisely the supraspinatus, the infraspinatus, the infraspinatus, the teres minor, the teres minor, and the subscapularis. and the subscapularis. The teres major is not part of the rotator cuff because its function is not to rotate. The teres major is not part of the rotator cuff because its function is not to rotate. I repeat, I repeat, The muscle tendon or rotator cuff is the supraspinatus, the muscle tendon or rotator cuff is the supraspinatus, infraspinatus, infraspinatus, teres minor, teres minor, and subscapularis. and subscapularis. That is always important for you to know in medicine. That is always important for you to know in medicine. So friends, So friends, that has been the entire video. that has been the entire video. Don't forget to subscribe in the little circle that appears here, Don't forget to subscribe in the little circle that appears here, give it a like. give it a like. You can follow me on Instagram at at upcoseacuteenches1315. You can follow me on Instagram at at upisiosiacuteenches1315. Here are the links to more of my videos so you can watch them and don't forget to subscribe. Here are the links to more of my videos so you can watch them and don't forget to subscribe.

Hello, Hello, my dear colleagues. my dear colleagues. Today I bring you a video about the anatomy of the muscles of the upper limb.

Today I bring you a video about the anatomy of the muscles of the upper limb. More specifically, More specifically, we will talk about the anatomy of the muscles of the shoulder and pectoral regions. we will talk about the anatomy of the muscles of the shoulder and pectoral regions.

Before starting this video, Before starting this video, I invite you to subscribe to my channel. I invite you to subscribe to my channel. Here in the lower right corner, Here in the lower right corner, you will find a link that, you will find a link that, if you click on it, if you click on it, you will be subscribed to the channel and can access more content. you will be subscribed to the channel and can access more content. Before starting, Before starting, I will put the cursor here again, I will put the cursor here again, because I always forget to put it here.

because I always forget to put it here. Very well, Very well, we already have the pointer ready. we already have the pointer ready. So, So, well, well, let's divide this class into three muscle groups. let's divide this class into three muscle groups.

The first muscle group that we will talk about are the muscles found in the pectoral region, The first muscle group that we will talk about are the muscles found in the pectoral region, which are four. which are four. We will talk about the pectoralis major and minor, We will talk about the pectoralis major and minor, the suclavius muscle, the suclavius muscle, and the serratus anterior muscle. and the serratus anterior muscle. Although these are muscles found in a region that is practically thoracic.

Although these are muscles found in a region that is practically thoracic. Their function is towards the upper limb and that is why they are studied as muscles of the upper limb. Their function is towards the upper limb and that is why they are studied as muscles of the upper limb.

Then we will talk about the superficial muscles of the back, Then we will talk about the superficial muscles of the back, which are the same. which are the same. They are muscles located in the back of the chest, They are muscles located in the back of the chest, but their function is to move the upper limb.

but their function is to move the upper limb. Here we will talk about five muscles, Here we will talk about five muscles, the trapezius, the trapezius, the latissimus dorsi, the latissimus dorsi, the scapulae angle, the scapulae angle, and the rhomboids. and the rhomboids. And finally, And finally, we will talk about the muscles of the shoulder region, we will talk about the muscles of the shoulder region, which are six. which are six.

They are the ones that start the upper limb itself, They are the ones that start the upper limb itself, which are the deltoid, which are the deltoid, the subscapularis, the subscapularis, the supraspinatus, the supraspinatus, and the infraspinatus, and the infraspinatus, and the teres major and minor. and the teres major and minor. We will quickly begin by explaining what the origin and insertion are. We will quickly begin by explaining what the origin and insertion are.

Something basic that you have to learn with each muscle in the human body is that you have to learn to do four fundamental things. Something basic that you have to learn with each muscle in the human body is that you have to learn to do four fundamental things. First, First, the origin, the origin, then the insertion, then the insertion, then the innervation, then the innervation, that is, that is, which nerve makes that muscle move. which nerve makes that muscle move. and finally the function.

and finally the function. So, So, very often you confuse what the origin and insertion are, very often you confuse what the origin and insertion are, and they are not the same. and they are not the same. In fact, In fact, it is a little trick.

it is a little trick. If you learn the difference between origin and insertion, If you learn the difference between origin and insertion, basically by learning only the origin, basically by learning only the origin, insertion, insertion, and direction of a muscle, and direction of a muscle, you can infer what the function of that muscle is. you can infer what the function of that muscle is. Let me explain.

Let me explain. Every muscle has two roots, Every muscle has two roots, two ends. two ends. One is the origin and the other is the insertion.

One is the origin and the other is the insertion. Many authors call the origin a fixed insertion and the insertion a mobile insertion. Many authors call the origin a fixed insertion and the insertion a mobile insertion.

What does this mean? What does this mean? The origin is the part of the muscle that does not move.

The origin is the part of the muscle that does not move. That is, That is, it is the fixed part of the muscle, it is the fixed part of the muscle, which is why they call it a fixed insertion, which is why they call it a fixed insertion, while the part of the muscle that is going to move, while the part of the muscle that is going to move, that is, that is, the part that is going to be cut, the part that is going to be cut, the part that shrinks, the part that shrinks, is the insertion. is the insertion.

And that is why they call it a mobile insertion. And that is why they call it a mobile insertion. Here the example is with the vice brachialis. Here the example is with the vice brachialis.

its fixed portion. its fixed portion. Its origin is at the level of the coracoid process and the scapula. Its origin is at the level of the coracoid process and the scapula. That is the part of the muscle that does not move.

That is the part of the muscle that does not move. So, So, its insertion is going to be at the radial level. its insertion is going to be at the radial level.

That's why when it contracts, That's why when it contracts, it doesn't just grab the radius to move my scapula, it doesn't just grab the radius to move my scapula, because I'm explaining to him that the scapula is the origin. because I'm explaining to him that the scapula is the origin. It's going to grab the scapula, It's going to grab the scapula, which is its origin, which is its origin, to perform its function in the insertion, to perform its function in the insertion, which is to move the radius and thus flex my forearm.

which is to move the radius and thus flex my forearm. So, So, it's very important that you fix these two things. it's very important that you fix these two things.

We're going to see it during the video, We're going to see it during the video, because this mnemonic is very easy to learn the origin and insertion, because this mnemonic is very easy to learn the origin and insertion, as well as their differences. as well as their differences. So, So, let's start first with the muscles of the pectoral region.

let's start first with the muscles of the pectoral region. At this level, At this level, we're going to find four muscles. we're going to find four muscles.

We're going to go from superficial to deep. We're going to go from superficial to deep. First, First, we'll talk about the pectoralis major muscle.

we'll talk about the pectoralis major muscle. As you can see, As you can see, this is a muscle that originates on the lower edge of the clavicle, this is a muscle that originates on the lower edge of the clavicle, on the lateral edge of the sternum, on the lateral edge of the sternum, as well as on the six costal caudal edges that are located posteriorly. as well as on the six coastal caudal edges that are located posteriorly.

Many authors also describe its origin as being at the level of what is called the ponorosis of the oblique major muscle, Many authors also describe its origin as being at the level of what is called the ponorosis of the oblique major muscle, also called the external oblique. also called the external oblique. So this muscle moves laterally, So this muscle moves laterally, curves, curves, that is, that is, rolls up, rolls up, and inserts into the vixipital groove of the humerus.

and inserts into the vixipital groove of the humerus. If I explain to you that the origin is at this medial level and the insertion is lateral, If I explain to you that the origin is at this medial level and the insertion is lateral, it is not that he is going to grab the number to move my sternum and clavicle, it is not that he is going to grab the number to move my sternum and clavicle, because you already know that this is the origin. because you already know that this is the origin.

So, So, he grabs the origin, he grabs the origin, which is the sternum and the clavicle, which is the sternum and the clavicle, to move my arm. to move my arm. And if you look at this image, And if you look at this image, what function do you think the pectoralis major will have?

what function do you think the pectoralis major will have? When it contracts, When it contracts, since it is going to contract at the insertion level, since it is going to contract at the insertion level, it moves the arm inwards, it moves the arm inwards, that is, that is, medially. medially.

That is why it is an adductor of the arm, That is why it is an adductor of the arm, but in addition to adducting, but in addition to adducting, it also internally rotates the arm. it also internally rotates the arm. So, So, see how easy this neoteny of the origin and insertion is. see how easy this neoteny of the origin and insertion is.

Here you can see how the tendon of the pectoralis major muscle goes in front of the vice versa and is covered by the toid muscle to finally insert into the external lip of the vici-ip-pital groove. Here you can see how the tendon of the pectoralis major muscle goes in front of the vice versa and is covered by the toid muscle to finally insert into the external lip of the vici-ip-pital group. Now, Now, the next muscle is posterior to the pectoralis major. the next muscle is posterior to the pectoralis major. Look at this image here.

Look at this image here. On this side, On this side, they section the pectoralis major. they section the pectoralis major.

We find this aponeurosis which is the clavipectoral aponeurosis. We find this aponeurosis which is the clavipectoral aponeurosis. And then we section the clavipectoral aponeurosis to find this muscle which is the pectoralis minor muscle.

And then we section the clavipectoral aponeurosis to find this muscle which is the pectoralis minor muscle. So it will be found posterior to the pectoralis major. So it will be found posterior to the pectoralis major. This pectoralis minor muscle originates from the second to the fifth rib. This pectoralis minor muscle originates from the second to the fifth rib.

Although you see this image of the rib that is from the third to the fifth. Although you see this image of the rib that is from the third to the fifth. Well, Well, the theory says that it is from the second to the fifth.

the theory says that it is from the second to the fifth. So, So, I'm giving it to you as the theory says, I'm giving it to you as the theory says, but not as shown in the image, but not as shown in the image, because remember that there are many anatomical variations and we don't know if this cadaver that Netter used for this drawing was one of those anatomical variations. because remember that there are many anatomical variations and we don't know if this cadaver that Netter used for this drawing was one of those anatomical variations. So this pectoralis minor muscle originates from the second and fifth ribs and inserts into the coracoid process of the scapula. So this pectoralis minor muscle originates from the second and fifth ribs and inserts into the coracoid process of the scapula.

So, So, it's not like it's going to grab onto the coracoid process to raise my ribs. it's not like it's going to grab onto the coracoid process to raise my ribs. because I'm explaining to you that the origin is down here.

because I'm explaining to you that the origin is down here. So, So, its function is going to be to lower the coracoid process. its function is going to be to lower the coracoid process.

That's why it's said that its function is to lower the shoulder. That's why it's said that its function is to lower the shoulder. So, So, who supplies the two pectorals? who supplies the two pectorals?

The pectoralis major and pectoralis minor nerves, The pectoralis major and pectoralis minor nerves, which are branches of the secondary trunks of the anterolateral and antero-internal brachial plexus. which are branches of the secondary trunks of the anterolateral and antero-internal brachial plexus. It's very important that you watch my video on the brachial plexus.

It's very important that you watch my video on the brachial plexus. At the end of this video I will leave you the link so that you can understand where the nerves that move these muscles come from. At the end of this video I will leave you the link so that you can understand where the nerves that move these muscles come from. So, So, we have already covered two of the four. we have already covered two of the four.

We talked about the pectoralis major and minor. We talked about the pectoralis major and minor. Now we are going to talk about the subclavius muscle.

Now we are going to talk about the subclavius muscle. As its name suggests, As its name suggests, it is located below the clavicle, it is located below the clavicle, which is the clavicle. which is the clavicle.

This subclavius muscle originates at the junction of the first rib with the first coastal cartilage and inserts into a canal on the underside of the clavicle. This subclavius muscle originates at the junction of the first rib with the first coastal cartilage and inserts into a canal on the underside of the clavicle. Basically, Basically, its innervation is through the subclavian nerve.

its innervation is through the subclavian nerve. which is a nerve that derives from the brachial plexus, which is a nerve that derives from the brachial plexus, specifically from the superior primary trunk. specifically from the superior primary trunk. Its function is to keep this external clavicular joint stable and prevent it from displacing the head of the clavicle from coming out of the clavicular fossa, Its function is to keep this external clavicular joint stable and prevent it from displacing the head of the clavicle from coming out of the clavicular fossa, which is the external sternum. which is the external sternum.

That is basically the function of the subclavius muscle. That is basically the function of the subclavius muscle. And finally, And finally, within this muscle, within this muscle, this group of muscles in the pectoral region, this group of muscles in the pectoral region, we are talking about the serratus anterior muscle.

we are talking about the serratus anterior muscle. In many books, In many books, you can find it under the name of serratus anterior. you can find it under the name of serratus anterior. It is the same as serratus major and serratus anterior.

It is the same as serratus major and serratus anterior, It is called that because it looks like a saw, it is called that because it looks like a saw, a hacksaw. a hacksaw. Its origin is eight digits from the first to the eighth rib.

Its origin is 8 digits from the first to the 8th rib. That is its origin. That is its origin. This muscle runs laterally, This muscle runs laterally, goes in front of the scapula to finally insert on the medial edge of the scapula. goes in front of the scapula to finally insert on the medial edge of the scapula.

So, So, when it retracts, when it retracts, the scapula basically goes out. the scapula basically goes out. That is why its function is to abduct the arm. That is why its function is to abduct the arm.

because when I move the scapula out, because when I move the scapula out, the humerus that is attached to the scapula goes out as well. the humerus that is attached to the scapula goes out as well. That is the abduction movement.

That is the abduction movement. The innervation of the serratus major is the nerve of the serratus major, The innervation of the serratus major is the nerve of the serratus major, also called the long thoracic nerve. also called the long thoracic nerve.

Very well, Very well, those are the muscles of the pectoral region. those are the muscles of the pectoral region. Let's now move on to the superficial muscles of the back, Let's now move on to the superficial muscles of the back, which are five. which are five.

To start with the first of these five, To start with the first of these five, we're going to talk about the trapezius muscle. we're going to talk about the trapezius muscle. It's called that because it's really shaped like a trapezius. It's called that because it's really shaped like a trapezius. It has a very extensive origin.

It has a very extensive origin. It's said to originate from the superior curved line of the occiput, It's said to originate from the superior curved line of the occiput, external occipital protuberance, external occipital protuberance, posterior cervical ligament, posterior cervical ligament, also called the nuchal ligament, also called the nuchal ligament, spinous process of S7, spinous process of S7, which is this very prominent one that you see here, which is this very prominent one that you see here, as well as the spinous process of all the thoracic vertebrae without exception. as well as the spinous process of all the thoracic vertebrae without exception.

In addition, In addition, it's also said to originate from what is called the supraspinous ligament. it's also said to originate from what is called the supraspinous ligament. So, So, Notice that this entire medial area is the origin.

Notice that this entire medial area is the origin. Now, Now, its insertion is going to be on the upper lip of the spine of the scapula. its insertion is going to be on the upper lip of the spine of the scapula.

And when I rotate the image, And when I rotate the image, this would be the acromion of the scapula and here the external third of the clavicle. this would be the acromion of the scapula and here the external third of the clavicle. It is then inserted into the spine of the scapula, It is then inserted into the spine of the scapula, the chroma of the scapula, the chroma of the scapula, and the external third of the clavicle, and the external third of the clavicle, innervated by the cervical plexus, innervated by the cervical plexus, that is, that is, C3, C3, C4, C4, plus the trunk of a cranial nerve, plus the trunk of a cranial nerve, which is the 11th cranial nerve.

which is the 11th cranial nerve. also called the accessory nerve. also called the accessory nerve.

Since its insertion is in the scapula, Since its insertion is in the scapula, its function is going to be in the scapula and that is precisely to rotate and elevate the scapula. its function is going to be in the scapula and that is precisely to rotate and elevate the scapula. Let's move on to the latissimus dorsi muscle. Let's move on to the latissimus dorsi muscle.

This muscle has a broad origin. This muscle has a broad origin. It is also said that it is in the last five thoracic vertebrae, It is also said that it is in the last five thoracic vertebrae, that is, that is, from 8 to 12, from 8 to 12, as well as in all the lumbar and sacral vertebrae through this peneurosis that you see here, as well as in all the lumbar and sacral vertebrae through this peneurosis that you see here, which is the famous columbar peneurosis.

which is the famous columbar peneurosis. In addition, In addition, it has a fascicle of origin from the iliac crest of the iliac bone. it has a fascicle of origin from the iliac crest of the iliac bone. This muscle is the most superficial of the back, This muscle is the most superficial of the back, along with the trapezius, along with the trapezius, and it goes laterally to insert into the vicissitudes.

and it goes laterally to insert in the iliac bone. into the vicissitudes. So its function, So its function, when it contracts, when it contracts, is to reach the vicissitudes precisely here, is to reach the vicissitudes precisely here, so that you understand the anatomical arrangement of this muscle.

so that you understand the anatomical arrangement of this muscle. And when it contracts, And when it contracts, the arm basically goes inward, the arm basically goes inward, that is, that is, medially. medially.

That is why it is said to be an adductor of the arm. That is why it is said to be an adductor of the arm. Also, Also, since it is a muscle that grips the arm towards the back, since it is a muscle that grips the arm towards the back, when it contracts, when it contracts, it takes the arm posteriorly, it takes the arm posteriorly, which is why it is said to be both an adductor and an extensor of the arm.

which is why it is said to be both an adductor and an extensor of the arm. It is innervated basically by the latissimus dorsi nerve, It is innervated basically by the latissimus dorsi nerve, also called the thoracodorsal nerve. also called the thoracodorsal nerve.

Look carefully at this image, Look carefully at this image, how it is originating in the lower dorsal vertebrae, how it is originating in the lower dorsal vertebrae, as well as in the lumbar vertebrae. as well as in the lumbar vertebrae. And here you can see the origin of the iliac crest, And here you can see the origin of the iliac crest, the iliac bone. the iliac bone.

There are now many books that describe an origin that comes from the lower vertex of the scapula. There are now many books that describe an origin that comes from the lower vertex of the scapula. So it is very important to keep this origin in mind and here you can clearly see how the insertion occurs in the bicipital path.

So it is very important to keep this origin in mind and here you can clearly see how the insertion occurs in the bicipital path. So, So, in this diagram you can see that if the muscle contracts, in this diagram you can see that if the muscle contracts, the upper limb goes medially and that is adduction. the upper limb goes medially and that is adduction.

Let's now move on to the angle of the scapula. Let's now move on to the angle of the scapula. In most books you will find it under the name of the levator scapulae muscle. In most books you will find it under the name of the levator scapulae muscle.

Basically, Basically, with that you already know what the function of this muscle is. with that you already know what the function of this muscle is. It is said that it originates in the transverse processes of the vertebrae from C1 to S4, It is said that it originates in the transverse processes of the vertebrae from C1 to S4, specifically in the posterior tubercles and is inserted into the medial border of the scapula. specifically in the posterior tubercles and is inserted into the medial border of the scapula. Its innervation is by the cervical plexus.

Its innervation is by the cervical plexus. that is, that is, the anterior branch of C3-C4 and its function, the anterior branch of C3-C4 and its function, as you know, as you know, if it is called levator scapulae, if it is called levator scapulae, it must basically be to elevate the scapula. it must basically be to elevate the scapula. And then we move on to the rhomboid muscles.

And then we move on to the rhomboid muscles. In anatomy, In anatomy, it is very important for you to know that there are many structures that have the names of minor and major. it is very important for you to know that there are many structures that have the names of minor and major.

Almost always, Almost always, almost always, almost always, not always, not always, but almost always, but almost always, the minor is on top and the major is on the bottom. the minor is on top and the major is on the bottom. So, So, Basically this muscle that you see on top is the rhomboid minor and this one on the bottom is the rhomboid major.

Basically this muscle that you see on top is the rhomboid minor and this one on the bottom is the rhomboid major. Note that its origin is at the level of the spine. Note that its origin is at the level of the spine, Specifically it is the rhomboid minor at the level of the spinous process of C7 and D1.

specifically it is the rhomboid minor at the level of the spinous process of C7 and D1, While the rhomboid major is the spinous process from D2 to D5. while the rhomboid major is the spinous process from D2 to D5. So here it is C7 and D1, So here it is C7 and D1.

Here it is from D2 to C5 to D5, here it is from D2 to C5 to D5, sorry, sorry. and it inserts into everything that is the medial border of the scapula. And it inserts into everything that is the medial border of the scapula.

When these muscles contract, When these muscles contract, the scapula will go medially. the scapula will go medially. That is why you will see in the books that its function is to fix and retract the scapula.

That is why you will see in the books that its function is to fix and retract the scapula. The innervation will be basically through the rhomboid nerve, The innervation will be basically through the rhomboid nerve, which is also called the dorsal scapular nerve. which is also called the dorsal scapular nerve. Finally, Finally, we will go over the muscles of the shoulder region, we will go over the muscles of the shoulder region, of which there are six.

of which there are six. We will first talk about the most superficial of these muscles of the shoulder region, We will first talk about the most superficial of these muscles of the shoulder region, which is the deltoid, which is the deltoid, which is the one that gives the shoulder its roundness. which is the one that gives the shoulder its roundness.

that characteristic shape. that characteristic shape. This deltoid muscle, This deltoid muscle, let's say its origin is where the trapezius inserts. let's say its origin is where the trapezius inserts. Remember that the trapezius inserts into the spine of the scapula, Remember that the trapezius inserts into the spine of the scapula, the chromon of the scapula, the chromon of the scapula, and the lateral third of the clavicle.

and the lateral third of the clavicle. The same goes for the deltoid, The same goes for the deltoid, except that the trapezius inserts into the upper edge of these structures and the deltoid originates from the lower edge of these structures. except that the trapezius inserts into the upper edge of these structures and the deltoid originates from the lower edge of these structures.

See here in this back image how it is inserting, See here in this back image how it is inserting, originating, originating, sorry. sorry. where the trapezius inserts.

where the trapezius inserts. Its insertion is basically in the tuberosity, Its insertion is basically in the tuberosity, also called the deltoid V of the humerus, also called the deltoid V of the humerus, and it has several functions, and it has several functions, but the most important are to adduce and flex the arm, but the most important are to adduce and flex the arm, because when the arm contracts it goes outwards. because when the arm contracts it goes outwards.

Its innervation is provided by the axillary nerve, Its innervation is provided by the axillary nerve, also called the circumflex nerve of the brachial plexus. also called the circumflex nerve of the brachial plexus. Now we are going to talk about the spinous muscles.

Now we are going to talk about the spinous muscles. Remember that this structure is the spine of the scapula. Remember that this structure is the spine of the scapula.

So, So, the muscle that is located above it is the supraspinatus and the one that is basically below it is the infraspinatus. the muscle that is located above it is the supraspinatus and the one that is basically below it is the infraspinatus. In order to access these muscles, In order to access these muscles, we basically have to section both the trapezius and the deltoid.

we basically have to section both the trapezius and the deltoid. So this supraspinatus muscle, So this supraspinatus muscle, its origin is going to be in the supraspinous fossa. its origin is going to be in the supraspinous fossa.

It is going to pass through the spinoglenoid notch of the scapula and it is going to insert in the greater tuberosity. It is going to pass through the spinoglenoid notch of the scapula and it is going to insert in the greater tuberosity. also called the other tuberosity of the humerus. also called the other tuberosity of the humerus.

If it contracts, If it contracts, then the arm will go outwards. then the arm will go outwards. That's why it's said that it's an abductor of the arm and is innervated by the suprascapular nerve. That's why it's said that it's an abductor of the arm and is innervated by the suprascapular nerve.

The infraspinatus is easy. The infraspinatus is easy. If the supraspinatus originated in the supraspinatus fossa, If the supraspinatus originated in the supraspinatus fossa, the infraspinatus then originates in the infraspinatus fossa. the infraspinatus then originates in the infraspinatus fossa.

Its insertion, Its insertion, like the supraspinatus, like the supraspinatus, that is, that is, in the greater tuberosity of the humerus and its innervation is the same. in the greater tuberosity of the humerus and its innervation is the same. which is by the supraspinatus nerve. which is by the supraspinatus nerve.

What changes is the function. What changes is the function. I had told you that the supraspinatus is an abductor of the arm, I had told you that the supraspinatus is an abductor of the arm, while the infraspinatus, while the infraspinatus, which would be this one here, which would be this one here, is an external rotator of the arm.

is an external rotator of the arm. When the arm contracts, When the arm contracts, what it does is rotate, What it does is rotate, it turns. it turns. Now let's take a closer look at this image.

Now let's take a closer look at this image. This would be the supraspinatus and this one below would be the infraspinatus. This would be the supraspinatus and this one below would be the infraspinatus. See that both are reaching the greater tuberosity. See that both are reaching the greater tuberosity.

And in this superior view here we see the spinoglenoid notch, And in this superior view here we see the spinoglenoid notch. How the supraspinatus takes advantage of that gap. how the supraspinatus takes advantage of that gap. And here we see the infraspinatus reaching what is the humeral head.

And here we see the infraspinatus reaching what is the humeral head. Now we are going to talk about the subscapularis. Now we are going to talk about the subscapularis. This is an anterior view of the scapula. This is an anterior view of the the scapula.

Basically, Basically, what we are seeing up here is the supraspinatus, What we are seeing up here is the supraspinatus, which makes the names, which makes the names, and all this muscle that originates in the subscapular fossa is the famous subscapularis muscle. and all this muscle that originates in the subscapular fossa is the famous subscapularis muscle. That muscle inserts into the lesser tuberosity, That muscle inserts into the lesser tuberosity, also called the humeral tuberosity. also called the humeral tuberosity.

So, So, if you imagine that this is the origin, if you imagine that this is the origin, when it contracts at its insertion, when it contracts at its insertion, basically the head of the humerus will rotate, basically the head of the humerus will rotate, but not like the supraspinatus does, but not like the supraspinatus does, which makes it rotate outwards. which makes it rotate outwards, but rather it makes it rotate inwards. but rather it makes it rotate inwards. That's why its function is medial rotation or internal rotation of the arm and its innervation is provided by the superior subscapularis and inferior subscapularis nerves. That's why its function is medial rotation or internal rotation of the arm and its innervation is provided by the superior subscapularis and inferior subscapularis nerves.

Here we can see basically how the subscapularis passes behind this muscle which is the cobracobrachialis and behind the short head of the visbrachialis to be able to reach the lesser tuberosity or small bone of the humerus to be able to perform its internal rotation. Here we can see basically how the subscapularis passes behind this muscle which is the cobracobrachialis and behind the short head of the visbrachialis to be able to reach the lesser tuberosity or small bone of the humerus to be able to perform its internal rotation. Here we also see this upper image of the subscapularis muscle below. Here we also see this upper image of the subscapularis muscle below, You know, you know, the infraspinatus, the infraspinatus, below and also anterior.

below and also anterior. Now, Now, finally, finally, we are going to talk about the two round muscles, we are going to talk about the two round muscles, which are the teres minor, which are the teres minor, which is the one that is on top. which is the one that is on top. So, So, the one that is below, the one that is below, what should it be called? what should it be called?

Very good. Very good. It should be called teres major. It should be called teres major. So, So, do not confuse this one which is the supraspinatus, do not confuse this one which is the supraspinatus, infraspinatus, infraspinatus, sorry, sorry, these three fascicles with this one which is the teres minor and this one that is below, these three fascicles with this one which is the teres minor and this one that is below, which is the teres major.

which is the teres major. These muscles have the same origin, These muscles have the same origin. that is, that is, they originate in the infraspinatus fossa, they originate in the infraspinatus fossa. But what changes is their insertion. but what changes is their insertion.

Let's look at this image that is much closer. Let's look at this image that is much closer. See that its origin is at the level of the infraspinatus fossa. See that its origin is at the level of the infraspinatus fossa. This is the infraspinatus.

This is the infraspinatus. This is the supraspinatus. This is the supraspinatus. This would be the tendon of the infraspinatus.

This would be the tendon of the infraspinatus. And this one that is cut here would be the teres minor. And this one that is cut here would be the teres minor.

Its origin is in the south scapular fossa and it inserts into what is the greater tuberosity. Its origin is in the south scapular fossa and it inserts into what is the greater tuberosity. Its function is to externally rotate the arm. Its function is to externally rotate the arm. To give you an idea, To give you an idea, The infraspinatus together with the teres minor have the same function, the infraspinatus together with the teres minor have the same function.

which is external rotation of the arm. which is external rotation of the arm. Whereas unlike the teres minor, Whereas unlike the teres minor, the teres major, the teres major, which is the one below, which is the one below, which is this one, which is this one, is inserted into the viscipital groove, is inserted into the viscipital groove, specifically on the internal side, specifically on the internal side, and its function is to move the arm medially.

and its function is to move the arm medially. That is why it is an adductor of the arm, That is why it is an adductor of the arm, it has nothing to do with rotation. it has nothing to do with rotation. This teres major is innervated by the inferior subscapular nerve.

This teres major is innervated by the inferior subscapular nerve, while the teres minor is innervated by the circumflex nerve, while the teres minor is innervated by the circumflex nerve, which is the axillary nerve. which is the axillary nerve. Now, Now, in the next video that you are going to watch, In the next video that you are going to watch, we are going to talk about what the rotator cuff is, we are going to talk about what the rotator cuff is, which is a muscle tendon structure formed by four muscles. which is a muscle tendon structure formed by four muscles. We have already seen those four muscles, We have already seen those four muscles, which are precisely the supraspinatus, which are precisely the supraspinatus, the infraspinatus, the infraspinatus, the teres minor, the teres minor, and the subscapularis.

and the subscapularis. The teres major is not part of the rotator cuff because its function is not to rotate. The teres major is not part of the rotator cuff because its function is not to rotate.

I repeat, I repeat, The muscle tendon or rotator cuff is the supraspinatus, the muscle tendon or rotator cuff is the supraspinatus, infraspinatus, infraspinatus, teres minor, teres minor, and subscapularis. and subscapularis. That is always important for you to know in medicine.

That is always important for you to know in medicine. So friends, So friends, that has been the entire video. that has been the entire video.

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Transcript for:Resumen de los Músculos del Miembro Superior

Transcript for:
Resumen de los Músculos del Miembro Superior