 this session on osteology of upper limb. In this session, we will be beginning with the bone which is clavicle. Clavicle is usually the first bone to be studied in upper limb, so we are beginning with this bone. So, before beginning with the clavicle, let us have a brief overview of all the bones of the upper limb and then we will start with the clavicle proper. So, here we can see all the bones of the upper limb. This picture shows the bones viewed from the anterior aspect and this picture shows the bones viewed from the posterior aspect. Orientation for this image is, this is the medial aspect, lateral aspect, superior and inferior. So, let us try to identify which are the bones which are visible. So, this bone is the clavicle, then this is the scapula, then this bone of the arm is humerus, then in the forearm there are two bones, the lateral bone is radius and the medial bone is ulna, then these are the carpal bones, bones of the wrist, carpals and then there are metacarpals. Carpals are eight in number, metacarpals are five in number and then there are phalanges. Phalanges are fourteen in number. All tingles have got three phalanges except the thumb which has got two phalanges. That is how phalanges are fourteen in number. So, these are all the bones. So, this picture shows the bones viewed from the anterior aspect and this image shows the bones viewed from the posterior aspect. Prominent features in the posterior aspect are, here we can see one prominent feature, this is the spine of the scapula which is seen on the posterior aspect. Humerus on the posterior aspect presents a groove which is called as radial groove, then there is an olecranon fossa which is on the posterior aspect which is of the humerus, then these are the radius and ulna. Radius shows a prominent feature on the posterior aspect which has got a tubercle, that tubercle is called as Lister's tubercle. Then these are the carpals and the metacarpals and phalanges. So, this is just a brief overview of all the bones of the upper limb. Now, let us begin with the clavicle proper. So, clavicle bone will be learning in under following headings. First we will see which type of bone is it, then the site determination of clavicle, then parts of the clavicle, then attachments of the clavicle, attachments will see muscle attachments as well as attachments of the ligaments of the clavicle, then joints formed by the clavicle, there are certain peculiarities of the clavicle which are listed, we will see what are those and lastly the applied anatomy related to it. So, let us begin, type of bone and site determination, clavicle is which type of bone, if ask clavicle is which type of bone, it is an example of a modified long bone, it is an example of a modified long bone. It is called as modified long bone because it has got certain characteristic features which are different from that of a typical long bone, we will see what are those features later on, but if ask which type of bone it is, it is a modified long bone and for site determination of the clavicle, for any bone site determination we have to justify the site with these three dimensions, medial lateral, anterior posterior, superior, interior, whenever we say side of a bone we should justify in three dimensions, we should say which part of the bone is medial or lateral, which part of the bone is anterior or posterior and which part of the bone is superior or interior. So, here in this image we can see both the clavicles viewed from the superior aspect, this is the right clavicle and this is the left clavicle. If I have to say that this clavicle is of the right side, then what all points I have to say, this is the clavicle of the right side because if I see the first dimension medial and lateral, the medial end of the clavicle, here we can see this, this medial end of the clavicle, this is quadrangular whereas the lateral end of the clavicle, this is flatter. This one point we can say for medial and lateral, the medial end is quadrangular or else we can say the lateral end of the clavicle is flatter. Then for anterior, posterior we can say this is the junction between the medial two-thirds of the clavicle and the lateral one-thirds of the clavicle. The medial two-thirds of the clavicle is convex on the anterior aspect. So, for anterior, posterior we can say the medial two-thirds of the clavicle is convex on the anterior aspect. And for superior inferior, there is a specific point which is seen on the inferior aspect of the clavicle. When we see the clavicle on the inferior aspect, below this lateral one-third of the clavicle, there is a sharp elevation which is referred to as the conoid tubercle. So, that conoid tubercle should be on the inferior aspect. So, that is not seen on the superior aspect. So, superiorly the clavicle is entirely smooth, but whereas on the inferior aspect it has got some rough elevations. One of the prominent elevations is conoid tubercle which should be on the inferior aspect. That is how we can say that this is the clavicle of that particular side. So, this is the clavicle of the right side because the medial end is quadrangular. The medial two-thirds of the clavicle is facing. It is convex on the anterior aspect and the conoid tubercle is on the inferior aspect. So, when we say the statement justifying the side we should cover these three dimensions. Once we have justified these three dimensions then we can specifically say that this is the bone of the particular side. Now, let us see the parts of the clavicle. So, this is the clavicle viewed from the superior aspect. First I will orient you towards the image. Supposing this is the right clavicle viewed from the superior aspect. So, that this is the anterior aspect, this is the posterior aspect, this is the medial aspect and this is the lateral aspect. Imagine you are viewing the right clavicle from the superior aspect. So, this is the medial end, lateral end and this is the anterior part and posterior part. So, parts of the clavicle we can say clavicle has got two ends. One is the medial end which is quadrangular and the lateral end which is flat. And the entire shaft of the clavicle can be divided into two parts, the medial two-thirds of the clavicle and lateral one-thirds of the clavicle. The entire clavicle can be divided into two parts, the medial two-thirds and the lateral one-third. Then we see the medial two-thirds of the clavicle. It has got four surfaces, a superior surface, inferior surface, then anterior surface and posterior surface. Whereas, when the lateral one-thirds of the clavicle, it has got two surfaces and two borders. Since it is flattened, it has got a superior surface, inferior surface and two borders, anterior border and posterior border. And this is the clavicle viewed from the inferior aspect. Now, again imagine the right clavicle and now you are viewing it from the inferior aspect. Now, let us give orientation to this image. You are viewing the right clavicle from the inferior aspect. This is the anterior part, this is the posterior part, this is the medial part and this is the lateral part. So, right clavicle viewed from the inferior aspect, this is the medial end and this is the lateral end. Inside determination, I was talking about the ponoid tubercle. You can see this sharp elevation here. This is the ponoid tubercle. So, ponoid tubercle should always be on the inferior aspect when the bone is held in anatomical position. That is how we can specifically determine the side of the clavicle. Inside determination, this ponoid tubercle is one of the most important thing which has to be looked for. Otherwise, it may be difficult to identify the side of the clavicle. So, on the inferior surface of the clavicle, one most important feature is the ponoid tubercle and there is a ridge extending from the ponoid tubercle. That ridge is referred to as trapezoid ridge and there is a groove here on the inferior surface of the clavicle which is referred to as the subclavian groove. Groove is referred to as the subclavian groove. Along the medial aspect, there is a rough oval impression for the ligament which is called as costoclavicular ligament. On the inferior aspect of the clavicle, there are two ligaments attached. On the medial aspect, there is costoclavicular ligament and along the lateral aspect, there is coricoclavicular ligament. So, there are impressions of these two ligaments which are seen on the inferior aspect. So, let us again summarize the parts of the clavicle. So, the entire clavicle we can say it has got two ends, a medial end which is corterangular, a lateral end which is flattened. Since the lateral end is flattened, it has got two surfaces and two borders. This is the superior surface and below will be the inferior surface. Here, this region is the inferior surface and the two borders are anterior border and posterior border. Then the medial two-thirds of the clavicle has got four surfaces, a superior surface, then inferior surface, then anterior surface and posterior surface. So, medial two-thirds of the clavicle is corterangular having four surfaces, superior, inferior, anterior and posterior. There are certain features along the inferior aspect of the clavicle. We learnt about the conoid, tubercle and trapezoid ridge. Then along the medial aspect, there is an overall impression for costoclavicular ligament. Then there is a shallow groove for a muscle, subclavius muscle. The groove is named as subclavian groove. So, these were the various parts of the clavicle. Now, let us move on to the attachments of the clavicle. So, here there is a schematic diagram to show the attachments of the clavicle. This is the clavicle viewed from the superior aspect. Similar image I have taken. Again, first let us orient ourselves and then we will try to understand the various attachments. Supposing this is the right clavicle viewed from the superior aspect, this is the anterior aspect, posterior aspect, lateral and medial. So, we are viewing the right clavicle from the superior aspect. So, which are the muscle attachments which are seen? This is the junction of the medial two-thirds and the lateral one-thirds of the clavicle. In the lateral one-thirds of the clavicle, we can see on the anterior border of the lateral one-third of the clavicle, the muscle attached is deltoid. To be more specific, it is the anterior fibres of the deltoid muscle. Along the posterior aspect of the lateral one-thirds of the clavicle, the muscle attached is trapezius. To be more specific, it is the upper fibres of the trapezius. So, two muscles we have covered in the lateral one-thirds of the clavicle. One is the deltoid on the anterior aspect and trapezius on the posterior aspect. Then along the medial two-thirds of the clavicle, on the anterior surface, the muscle attached is pectoralis major. So, anterior surface of the medial two-thirds of the clavicle, the muscle attached is pectoralis major. This muscle here on the superior surface, the medial half of the superior surface, the muscle attached is sternocleidomastoid. The muscle attached is sternocleidomastoid. The name of the muscle is sternocleidomastoid because it has got attachments on the sternum cleido. The word cleido refers to the clavicle and then it has got attachments on the mastoid process of the skull as well. That is why the name of the muscle is sternocleidomastoid. So, the word cleido referring to the clavicle. So, on the superior surface of the clavicle, medial half the muscle attached is the sternocleidomastoid. So, in this image, we have covered four muscles along the lateral one-thirds. The muscle was deltoid and trapezius. Then along the medial two-thirds of the clavicle, the muscle was pectoralis major and sternocleidomastoid. Then here we can see the inferior aspect of the clavicle. We had learned about a groove on the inferior surface of the clavicle. The groove was subclavian groove. And the muscle attached is subclavius. Muscle attached is subclavius. Attachments when it is shown in red, red color, it means the muscle is originating from that bone. If the color is shown blue color, that means there is insertion of that muscle. In general, as a rule in anatomy, you can remember if in standard books, the red colored markings are given on the bone that indicates that that is the origin of that muscle. And if blue colored markings are given on the bone, that means that is the insertion of that muscle. The other parts which are seen on the inferior aspect, we have already covered in the superior aspect. This is deltoid, this is trapezius, then this is pectoralis major. So, the most prominent muscle which is on the inferior aspect of the clavicle is subclavius muscle. So, these are the five muscles which you need to remember for the attachments of the clavicle. I will repeat again. One is the deltoid, then trapezius. These two muscles are on the lateral one-thirds of the clavicle. Then along the medial two-thirds of the clavicle, the muscle is pectoralis major. Then sternocleidomastoid. Then along the inferior aspect of the clavicle, the muscle is subclavius. So, these are the various muscle attachments in the clavicle. Legament attachments of the clavicle we had already covered previously. Can we just recollect which was the ligament attached on to the clavicle? This overall impression here, the ligament attached was costoclavicular ligament and the projection here, conoid tubercle give detachment to a ligament, coraco-clavicular ligament. Coraco-clavicular ligament. Coraco-clavicular ligament has got two parts. One is the conoid part, another is the trapezoid part. So, conoid part will attach on to the conoid tubercle and trapezoid part will attach on to the trapezoid ridge which is on the inferior surface of the lateral one-thirds of the clavicle. So, ligaments, costoclavicular ligament, coraco-clavicular ligament. There is one more ligament which connects the clavicle of the opposite side. That means the two clavicles are interconnected by a ligament which is called as inter-clavicular ligament, okay? There is one more ligament which we can add on, that is the inter-clavicular ligament. Let us move on to the next heading, that is the joint formed by the clavicle. Joint formed by the clavicle, here first orient yourself, there is the skeleton built from the anterior aspect. This is the, sorry, this is the medial aspect, lateral aspect, superior and inferior. So, here we can say this is the clavicle. The medial end of the clavicle, it articulates with the sternum. The joint is sternoclavicular joint and the lateral one-thirds of the, sorry, the lateral end of the clavicle, it articulates with the acromion process. This is the acromion process of the scapula. This joint is acromoclavicular joint, acromoclavicular joint, okay? So, we have the two joints formed by the clavicle. We should also know the type of the joint. This sternoclavicular joint, it is an example of a saddle variety of synovial joint, whereas this acromion clavicular joint, it is an example of a plane variety of synovial joint, okay? So, these were the joints formed by the clavicle and the type of the joints, okay? Let us move on to the peculiarities of the clavicle. The certain peculiarities of the clavicle which examiners are found asking in the practical examinations or the VIVA examinations, so you should be aware of these peculiarities. It is the only long bone which lies horizontally. It is the only long bone which lies horizontally in the body. It is subcutaneous throughout. We can feel the clavicle in its entire extent. The clavicle does not have any medullary cavity, okay? There is no medullary cavity inside the clavicle. It is the first bone to start ossifying. Ossification of bones is the process of formation of the bones and the clavicle is the first bone to start ossifying. The second bone to start ossifying is the mandible bone, okay? It has two primary centers of ossification. Usually long bones have a single primary center and two secondary centers for the ends, but clavicle is little bit different. It has got two primary centers of ossification and one secondary center of ossification is usually there in the medial end of the clavicle. Then ossification of clavicle is through membranous ossification. Usually long bones ossify through cartilage, but clavicle ossifies through membranous ossification. It is occasionally pierced by a nerve which is called as intermediate supra-clavicular nerve, okay? This nerve at times pierces the clavicle and it usually pierces the clavicle at the junction of medial two-thirds and the lateral one-thirds of the clavicle, okay? So these are all the peculiarities of the clavicle. You can just take a screenshot of this image so that it is easy to revise before exam, okay? Let's move on to the next heading. Let's talk about the applied anatomy of the clavicle. Clavicle usually gets fractured at the junction of the medial two-thirds and the lateral one-third. Here we can see an image showing the fracture of the clavicle. The fracture usually occurs at the junction of the medial two-thirds and the lateral one-thirds of the clavicle because this is the weakest site of the clavicle as the curvature change of the clavicle occurs at this site and the ligament, the coraco-clavicular ligament is also attached at this site, so the weight transmission occurs through this region. So this is the weakest site of the clavicle and the clavicle is the most commonly fractured bone in the upper limb during fall on an outstressed hand, okay? So fracture of clavicle is one important applied aspect and then there is one more applied feature which is referred to as cledocranial disostosis. I'll just spell it out, cledocranial, cledocranial disostosis. Ostrosis refers to the bone formation, cledo refers to the clavicle, cranial refers to the cranial bones. So in this clinical condition, the clavicle may be partially absent or it may be completely absent and it will be associated with cranial deformities, deformities in the formation of the cranial bone, okay? So this is one like developmental condition it is congenitaly absent, clavicle is absent, okay? So fracture of the clavicle and cledo-cranial disostosis are some applied aspects. So this was all about the applied anatomy of the clavicle. Let's move on to the summary, okay? So let's summarize what we have covered in this session. We started with the type of the bone. Which type of bone is clavicle? It is an example of a modified long bone. Side determination, we learned how a bone has to be determined side in three dimensions. We should cover the point covering the medial and lateral dimension, the anterior and the posterior dimension, the superior and the inferior dimension. In the various parts of the clavicle, the medial and lateral end, in the medial two-thirds of the clavicle, how it has got four surfaces, anterior, posterior, superior and inferior. Then the lateral one-thirds of the clavicle has got two surfaces and two borders. Then along the inferior aspect of the clavicle, we saw there was conoid tubercle, trapezoid ridge, then subclavian groove, then oval facet on the medial aspect for costoclavicular ligament. All these features were on the inferior aspect of the clavicle. Then attachments, we learned about the various muscles attached to the clavicle. Along the lateral one-thirds of the clavicle, the muscle attached was, anteriorly there was deltoid muscle, posteriorly there was trapezius muscle. Along the medial two-thirds of the clavicle, on the anterior surface, the muscle was the pectoralis major. Along the superior surface, medial half, the muscle was sternocleidomastoid. Along the inferior aspect of the clavicle, the muscle was subclavius in the subclavian groove. These were the muscles and ligament attachments, the coricoclavicular ligament on the lateral aspect, costoclavicular ligament on the medial aspect and interclavicular ligament which connects the two clavicles. Joints formed on the medial aspect, the joint is sternoclavicular joint, which is the saddle variety of synovial joint. Then acromioclavicular joint on the lateral aspect, the joint is plane variety of synovial joint. Then we learned about various specularities of the clavicle and why it is called as modified long bone. In applied anatomy, we learned about the fracture of the clavicle, then cledocranial discostosis. This was all about the clavicle. In subsequent session, I will be covering the bone, which is scapula. If you have any doubts, then you can get back to me. Thank you.