 of the head and neck. In this session, we will be revising all the bones of the head and neck region. So, how many bones are there in the head and neck region? Here is the list. In all, there are 36 bones in the head and neck region. 22 bones are formed by the skull of which 8 are cranial and 14 are facial. We will see the names of each of the bones subsequently. There are 6 ear ossicles, 7 cervical vertebrae and 1 hyoid bone. All these bones will be covering in this particular session. So, let us start with the skull first. While studying skull, we should be knowing about various terms which are used while describing the skull. There are many terms which at times students get confused. So, I have listed down all the terms. And we speak about skull. Skull means the entire thing which is seen. Here, whatever is seen in the image, this is skull. And what is cranium? When the mandible is removed from the skull, the remaining portion is referred to as cranium. Then, what is chalveria? Chalveria, skull vault and skull cap. These three names are synonymous. This refers to the upper part of the cranium. Then, basic cranium, skull base and cranial base. These three terms are synonymous. This refers to the basal part of the cranium. So, these are various terms which you should be knowing. These three terms are synonymous. Basic cranium, skull base and cranial base. These three terms are synonymous. Chalveria, skull cap and skull vault. Skull is the entire thing and when the mandible is removed, then the specimen will be called as cranium. Let us see the parts of the skull. The two parts of the skull, one is the cranial skeleton and another is facial skeleton. Cranial skeleton is also referred to as neurocranium. Facial skeleton is also referred to as viscerocranium. In the image, we can roughly get an idea which part is cranial skeleton and which part is facial skeleton. This yellow colored area is the facial skeleton and the remaining is the cranial skeleton. The subsequent slides will see which all bones are included in which part of the skeleton. So, here we can see cranial skeleton consists of eight bones out of which pad bones are parietal bones and temporal bones. This is the parietal bone. This is the temporal bone. An unpaired bones include frontal bone, occipital bone, spinoid and ithmoid. The remaining bones are in the facial bones. There are 14 in number. Here also there are pad and unpaired bones. Unpaired bones include mandible and the vomer. And pad bones are maxilla. This is the maxilla bone and zygomatic bone, nasal bone, lacrimal bone and there is palatine and inferior nasal conca. In the lateral wall of the nose, the inferior nasal conca is a separate bone. And superior and middle nasal conca, these two are parts of the ithmoid bone. And apart from this, the ear, occipals are considered separately. Those are present in the middle ear, three in each side. This was about the bones forming the skull. Now let us learn about the exterior of the skull. The exterior of the skull is studied in the form of view. When the skull is viewed from the superior aspect, it is referred to as norma verticalis. So in my previous sessions, I taught you how to describe any view. First, we have to speak about the bones which are visible and the sutures visible in that view. Then any special features with respect to that view and lastly the applied anatomy related to that view. So in norma verticalis, which bones are visible, here we can see this is the frontal bone and these two are the parietal bones and some part of occipital bone is also seen. These bones are visible in norma verticalis. Sutures visible are, this is the coronal suture between frontal bone and two parietal bones. And this is the phagietal suture between two parietal bones. And this is the lambdoid suture between two parietal bones and the occipital bone. And there may be metopic suture. What is metopic suture? It may be present in between the two halves of the frontal bone. These are the various sutures visible in norma verticalis. And various special features with respect to this view include one is bragma. What is bragma? It is the point of meeting of the coronal suture and the phagietal suture. This point is referred to as bragma. And what is vertex? Vertex is the highest point on the skull, on the sagittal suture. Then parietal eminence or parietal tuber, the elevations on the parietal bone convex elevations are referred to as parietal eminence or parietal tuber. Then parietal foramina, there is a small foramina just adjacent to the sagittal suture that is referred to as parietal foramina. Those transmit the emissary veins. And what is obelion? It is the point on the sagittal suture in between the two parietal foramina. Okay. So these are various special features with respect to norma verticalis. When I applied an admin related to this view, this bragma has got a great clinical significance. This is the reason of anterior fontanelle in fetal skull. This uses at the age of around 18 to 24 months. Okay. Then before its fusion, it is important clinically because if there is bulging of the anterior fontanelle, that means there could be hydrocephalus. And if there is depression of the anterior fontanelle, it means it could be dehydration. Okay. And also some drugs can be injected through the anterior fontanelle directly into the superior sagittal sinus. So this was about norma verticalis. Okay. Now we will move on to the other view. Let us study about the norma occipitalis. The skull viewed from the posterior aspect is referred to as norma occipitalis. Bones which are visible in this view are parietal bone. These were the parietal bones. And this is the occipital bone. And here this is the mastoid process that is referred to as the mastoid part of the temporal bone. Okay. These bones are visible in norma occipitalis. And sutures visible are there is a lambdoid suture. This suture is the lambdoid suture between parietal bone and the occipital bone. Then occipitomastoid suture between occipital bone and the mastoid part of the temporal bone. There is suture which is referred to as occipitomastoid suture. Between parietal bone and mastoid bone there is parietomastoid suture. Okay. In this image the sutures are not visible clearly. You all can refer my previous 3D sessions to understand these sutures more clearly. Okay. Then various special features with respect to this view is this point is referred to as lambda. The point of mating of the sugerital suture and the lambdoid suture. This point is lambda. It is the region of the posterior fontanel of the skull. Okay. Then external occipital protrobran. It is the most projecting point on the occipital bone. Okay. There is an elevation which is referred to as external occipital protrobran. The most prominent point on the external occipital protrobran is referred to as inion. Then external occipital crest. It extends from the external occipital protrobran up to the foramen magnum. Okay. There is a ridge which extends from external occipital protrobran to the foramen magnum that is external occipital crest. Then mastoid foramen. These are small foramen in the mastoid part of the temporal bone. Superior nuclear line, inferior nuclear line and highest nuclear line. These three are the nuclear lines which are described in Norma occipitalis. Just adjacent to the external occipital protrobran, the lines is superior nuclear line. Midway between the superior nuclear line and the foramen magnum, there is inferior nuclear line and 1 centimeter above the superior nuclear line is the highest nuclear line. Okay. Then applied anatomy related to Norma occipitalis. The point which we mentioned in the external occipital protrobran, inion, this point is used for cranometry for measuring the various dimensions of the skull. Then there could be sutural bones also referred to as vermian bones also called as Inca bone. At times there may be bones in between the sutures that are referred to as sutural bones. Then attachment of galia aponeurotica. It gets attached on to the highest nuclear line. At times highest nuclear line is absent. So in that case that will, it will be attached on to the superior nuclear line. Okay. And attachments of trapezius and sternocleidomastoid, those are also present in the superior nuclear line. Medial aspect will give attachment to the trapezius. Lateral aspect will give attachment to the sternocleidomastoid muscle. Okay. This was about Norma occipitalis. Now let's learn about Norma lateralis. Again following our same headings, the bones visible, sutures visible, special features and applied aspect. So which are the bones visible in Norma lateralis? The frontal bone, this is the frontal bone. This is the parietal bone. Now the posterior aspect occipital bone. This is the temporal bone. Then spinoid bone here, which this we can see this is the greater wing of the spinoid bone. Then zygomatic bone. This is the zygomatic bone. Mandible. This is the mandible. And maxilla. This is maxilla. Nasal bone. And lacrimal bone. Okay. So all these bones are seen in Norma lateralis. Sutures visible in this view are lambdoid suture. The suture which we saw in Norma occipitalis, some part is seen. Then coronal suture. Here we can see this is the coronal suture. Parieto squamous suture. Between parietal bone and this is referred to as the squamous part of the temporal bone. That's why this suture is referred to as parieto squamous suture. Okay. Then there are few other sutures. The suture here is zygomatico temporal suture. Then here this suture is seen. This is referred to as the frontal zygomatic suture. Okay. Then we have special features with respect to Norma lateralis. Therion. What is therion? It is a head shaped suture where four bones meet. So which are those four bones? This is the frontal bone, parietal bone, the temporal bone, and the greater wing of the spinoid bone. Okay. All these points, all these bones are meeting here in the region this is referred to as therion. There's a point on the posterior aspect which is referred to as a therion. Here three bones meet. One is the parietal bone, this is the temporal bone, and that is occipital bone. Okay. Then there is temporal line. There are two temporal lines superior and the inferior temporal line. Superior temporal line fades away. The inferior temporal line continues here. This region is referred to as the supramastoid crest. Okay. There's a triangular region here which is described. This is referred to as mech evens triangle. The boundaries are the supramastoid crest. The posterior superior margin of the external acoustic meitis and a tangent drawn along the posterior margin of the external acoustic meitis. This triangular region is used to approach the mastoid entrum for surgeries of the mastoid abscess. Okay. Then external acoustic meitis we saw, mastoid process. This is the mastoid process. One thing important about mastoid process is it is absent at birth. It is developed due to the pull of the sternocleidomastoid muscle. Okay. And here we can see this is the styloid process. Styloid process is also part of temporal bone. Then infratemporal posa. What is infratemporal posa? The part here below the or we can see inner aspect of the zygomatic arch and the ramus of the mandible is infratemporal posa. Above the zygomatic arch whatever space is seen that is referred to as temporal posa. Okay. This is temporal posa. Then applied aspects with respect to the normal lateral is. So, there are four bones meeting here. There is a common site of fracture in the skull and if it gets fractured at least to rupture of a blood vessel which is just beneath it as the anterior division of the middle meningeal artery and when it ruptures it leads to a clinical condition which is referred to as extradural hematoma. Okay. Then make even triangle is for mastoid surgery. In the temporal posa there is a muscle which is referred to as temporalis and the fascia which is which covers it is referred to as the temporalis fascia. That fascia is used for grafts of the ear. The tympanic membrane graft are usually taken from the temporal fascia. Okay. This was about normal lateralis. Now we will study about the normal front allis. So, skull view from the anterior aspect is referred to as normal front allis which are the bones visible in this view. There is the frontal bone and here there is nasal bone. This is maxilla on each side. This is zygomatic bone. This is mandible. So, all these bones are visible in normal frontalis. The few bones in the orbit as well which are visible. So, just visible in normal frontalis are frontal nasal suture between the frontal bone and the nasal bone. The suture is referred to as frontal nasal suture. In between the two nasal bones, the suture is referred to as inter nasal suture. Then frontal maxillary suture between the frontal bone and the maxilla there is a suture which is referred to as frontal maxillary suture. In zygomatico maxillary suture between zygomatic bone and maxilla. Okay. All these sutures are visible in normal frontalis. Also, there will be inter maxillary suture here in the midline. Okay. And special features in this view are nasion is the point where the frontal nasal suture meets with the inter nasal suture. Okay. That point is referred to as nasion. Then glabella is the point where the two supercillary arches meet. Just above the orbit, the elevation of bone is referred to as supercillary arch. Okay. The point of meeting of the two supercillary arches is referred to as glabella. Then naethion. What is naethion? This elevation in the midline is referred to as mental protuberance. The most prominent point here along the lower border of the mandible is referred to as naethion. Then what is acanthion? This nasal aperture has got a sharp projection in the lower aspect that is referred to as acanthion. The anterior nasal spines is referred to as acanthion. Mental protuberance we have covered. Then various foramans we have seen in normal frontalis. Above the orbital opening, there is a small opening which is referred to as supra-orbital foramen. And below it, there is intra-orbital foramen. And on the mandible, there is mental foramen. Okay. These three foramans lie in one line. An applied aspect with respect to normal frontal is include. The most common bone to be fractured in face is the nasal bone. Okay. Fractures of the facial bones, other facial bones are also common. Those are referred to as leaf force fracture. In details I described in the actual 3D sessions. Okay. You all can go through it. Then there are age-related changes with respect to the mental foramen. This mental foramen is at the lower aspect in children. It is in the intermediate part in adults and it moves higher up in old age. Okay. So this was about normal frontalis. Now we will see about the normal basalis. Skull view from the interior aspect is referred to as normal basalis. Okay. Students usually consider this normal basalis as the most tough part in the skull. But it is not that tough. If we logically try to remember, basalis is also simple. Okay. In normal basalis, in general, it is divided into three regions. The anterior part, intermediate part and posterior part. Anterior part is up to this posterior margin of this palate, our palate. Intermediate part is from this point to the anterior margin of the foramen magnum. And whatever is behind is referred to as the posterior part. So what all things are seen in the anterior part of normal basalis? The teeth are removed here. We will see the alveolar sockets. Okay. Alveolar processes will be seen in the maxilla. Then hard palate is formed by two bones. The anterior three-fourth part is formed by the maxilla. The posterior one-fourth part is formed by the palatine bone. Okay. This part is referred to as the horizontal plate of the maxilla. And here this will be referred to as the horizontal plate of the palatine bone. And there are sutures here. In between the two maxillary bones, there is intermaxillary suture. In between the two palatine bones, there is interpalatine suture. And in between the maxillary bone and palatine bone, there is palatomexillary suture. Okay. And we can see a small opening here just behind the incisor tooth. So this is the incisive fossa. Then along the lateral aspect of this palatine bone, there are two small openings. This referred to as the greater palatine foramen and lesser palatine foramen. Okay. So all these are the important things with respect to the anterior part of the norma basalis. Students usually get confused in the intermediate part of norma basalis because there are multiple openings which are seen in this intermediate part. We will try to simplify it. First let's try to identify the bones which are seen in this intermediate part. This part is the spinoid bone. And here this is the posterior aspect of the boomer bone. And these are the posterior nasal openings. Those are referred to as coenae. Okay. Then this is the part of the spinoid bone itself. The lateral pterigoid plate, the medial pterigoid plate. And in between the two pterigoid plate, there is a depression which is referred to as pterigoid fossa. Okay. And here there is the part of the temporal bone. So spinoid bone and temporal bone, they form majority of this intermediate part. Now let's see the openings which are seen in this intermediate part. Just adjacent to the spinoid bone. This opening which is seen, this is the foramen lacerum. Then in the spinoid bone certain openings are seen. This oval opening is referred to as foramen ovale. And this small opening behind foramen ovale that is foramen spinosum. And this opening which we can see, this is the carotid canal. And between the styloid process and the mastoid process, there's an opening which is referred to as the stylo mastoid foramen. So in the intermediate part if we know at least these openings it will be sufficient. I'll repeat again. The foramen lacerum, foramen ovale, foramen spinosum, carotid canal and the stylo mastoid foramen. If you at least know these openings and what structures pass through these openings, it will be sufficient for norma basalis. Then in the posterior part of norma basalis, this large opening which we can see, this is the foramen magnum. And there are projections that are adjacent to the foramen magnum. These are referred to as occipital condyles. Then in the temporal bone there's a depression which is referred to as mandibular posa which accommodates the head of the mandible. This is the mastoid process. And certain parts of the norma occipitalis are also seen in norma basalis. The external occipital protrobrans, the external occipital crest, those parts are also seen in norma basalis. Now we'll study about the cranial cavity. So here this is the specimen of cranial cavity. So to study the cranial cavity, the calvary has been cut open to expose the interior of the skull. Cranial cavity is also studied in three parts. This anterior part is referred to as the anterior cranial posa. Intermediate part is the middle cranial posa. The part behind is the posterior cranial posa. These three cranial posa are arranged step wise. The anterior cranial posa is at a higher level. The middle cranial posa is at the intermediate level. The posterior cranial posa is at the lowest level. What all structures are seen in anterior cranial posa? This is the orbital plate of the frontal bone. And on the inner aspect of the frontal bone, there's a elevation which is referred to as the frontal crest. And there's a projection here which is referred to as crista galli. Then adjacent to this crista galli, there is cryptiform plate of the ithmoid bone, which transmits multiple olfactory rootlets. Then this region is the lesser wing of the spinoid bone. So three bones seen in the anterior cranial posa are frontal bone, ithmoid bone, and the lesser wing of the spinoid bone. And here we can say this region is the middle cranial posa. The central part is formed by the body of the spinoid bone. The lateral part, it includes the greater wing of the spinoid as well as the temporal bones. Okay. What all structures are seen in this middle part? This projection here on of the lesser wing of the spinoid is the anterior clenoid process. Similarly, there is one on the posterior aspect that is referred to as posterior clenoid process. This projection here is referred to as the dorsum cellae. Okay. And this concave depression here is referred to as hypofysial posa, also referred to as cellatarsica. Then in the middle cranial posa also there are multiple openings. This adjacent to the body of the spinoid, this opening is the foramen lacerum. This oval opening is foramen ovale. Just behind the foramen ovale, there is foramen spinosum. Okay. And anteriorly there are two openings here. One is the superior orbital pitcher and foramen rotundum. Okay. There are four openings which lie in one arc. The superior orbital pitcher, foramen rotundum, foramen ovale and foramen spinosum. And let's see the posterior part of the cranial cavity. There is posterior cranial posa. This part of the bone is referred to as the petrus part of the temporal bone. There is an opening on the inner aspect of the petrus part of temporal bone, that is internal acoustic meiitis. Then here there is an opening which is referred to as jugular foramen. This opening is foramen magnum. There is a small opening seen, just anterior lateral to this foramen magnum, that is anterior condylar canal, also referred to as hypoglossal canal. Then on the inner aspect of the occipital bone, there are certain teachers. This projection here is the internal occipital protrobrin. Just like on the outer aspect, there is external occipital protrobrin. On the inner aspect, there is internal occipital protrobrin. Okay. And this crest is referred to as the internal occipital crest. And here we can see there are grooves for the transverse sinus, sigmoid sinus. The superior sagittal sinus continues as the right transverse sinus, which can be appreciated here. And that transverse sinus will continue as the sigmoid sinus, which will go up to the jugular foramen. So, we have revised the skull with all the foramen in detail. Now, I will add on slides which will cover the various structures passing through this foramen. Okay. Now, let's start with the mandible bone. Mandible is the bone of the lower jaw. Parts of the mandible. This part is referred to as the body of the mandible. And this is the ramus of the mandible on each side. Okay. The body of the mandible has got a superior border and an inferior border, an outer surface and an inner surface. The ramus of the mandible has got four borders, anterior border, posterior border, superior border, inferior border. And the two surfaces are the outer surface and the inner surface. Then various muscle attachments with respect to the mandible. On the outer aspect of the ramus of the mandible, the muscle is masseter muscle. And the oblique line there is the muscle which is referred to as Buxinator. And there are some muscles of the face which are attached here. And there are various muscles on the inner aspect of the mandible. This mandible is cut such that the left half of the mandible is viewed from the inner aspect. There's a muscle here along the angle of the mandible on the inner aspect that is the medial pterygoid muscle. Just below the head of the mandible, there is a small difference which is referred to as pterygoid fovea. The muscle attach this lateral pterygoid muscle. And this line is referred to as the mylohyoid line which gives attachment to the mylohyoid muscle. And this projection here, this is the coronoid process which gives attachment to a muscle that is temporalis muscle. These two projections are important in mandible. This is the head also referred to as the condylar process. And this is the coronoid process. And in between then this notch is referred to as mandibular notch. And this opening which we can see this is the mandibular foramen. Just anterior to the mandibular foramen there is a projection is referred to as the lingual of the mandible. And above the mylohyoid line the depression here is referred to as the sublingual fossa. Below the mylohyoid line the depression is sub mandibular fossa. In the midline on the posterior aspect there are four genial tubercles, two superior and two inferior. These genial tubercles are also referred to as mental spines. Various ligaments attached to the mandible. There is stylo mandibular ligament which gets attached along the angle of the mandible. Then lateral tempura mandibular ligament. There is a pterygo mandibular ligament also referred to as pterygo mandibular raffae. And there is a ligament which is attached along the lingual of the mandible that is referred to as the spinomandibular ligament. These are the four ligaments attached on to the mandible. Then various nerves related to the mandible. On the inner aspect if we see this opening transmits the nerve that is the inferior alveolar nerve. It passes through the mandibular foramen. Interior alveolar nerve gives a branch which passes through this region is referred to as the mylohyoid groove. The nerve here is nerve to mylohyoid. So interior alveolar nerve, nerve to mylohyoid. And there is a nerve near the neck of the mandible which is referred to as the auriculotemporal nerve. Then near the third molar tooth there is a nerve which is lingual nerve. These nerves are seen along the inner aspect of the mandible and on the outer aspect of the mandible there is a nerve which exits out through this mandibular notch to supply the masseter muscle that is the masseteric nerve. Then through the mental foramen a nerve exits that is the mental nerve and a nerve related along the interior margin of the body of the mandible that is marginal mandible or nerve. So in all there are seven nerves related to the mandible. Joints formed by the mandible, the head of the mandible it will articulate with the temporal bone. There is mandible or fossa which we saw in Norma Bezelis. This articulation is the temporal mandible or joint. The two halves of the mandible are connected in the midline by a simphysial joint that is referred to as the simphysis mentee. Name is simphysis but a joint actually behaves like a primary cartilaginous joint. Both halves of the mandible are fused. Then there is applied anatomy with respect to the mandible. One applied anatomy we covered in Norma Frontalis that is the age related changes of the mental foramen. Then mandible is prone to fracture. This neck of the mandible is the common sight for fracture of the mandible. Then this inferior alveolar nerve which is bypassed through this mandible or foramen. In dental procedures this nerve has to be blocked. So for that the lingula has to be palpated and the anesthetic agent is injected just behind the lingula of the mandibles. These were certain applied aspects with respect to the mandibles. Now we will cover the cervical vertebrae. Cervical vertebrae as we can see this is the cranial most part of the vertebral column. Just note the curvatures of the vertebral column. This cervical curvature is convex on the anterior aspect. Here it is magnified here. Cervical curvature is an example of a secondary curvature. It starts to develop at the age of three months when the baby starts holding the neck. Seven cervical vertebrae are divided into typical and atypical. Three, four, five, six are typical. First, second and seventh these are atypical cervical vertebrae. Here we can see this is the typical cervical vertebrae. What are the features which we can appreciate? The most important feature is this. This opening is the foramen transversarium. This opening is present that means it is cervical vertebrae. It is the cardinal feature of the cervical vertebrae. When we can see the body is more broad from side to side it is small from anterior posterior aspect. If we compare the body with this opening this is the vertebral foramen. Vertical foramen is larger as compared to that of the body of the vertebrae. In general when we describe the vertebrae we describe the vertebrae under two headings. One is the body and the remaining part is referred to as the vertebral arch. Votal components are included in vertebral arch. This transverse process, pedical, the articular process, lamina and the spinous process. All these are the components in the vertebral arch. There is characteristic feature with respect to the transverse process of cervical vertebrae because of this opening. The various parts which are described in the transverse process this part is referred to as the anterior root. The part behind is the posterior root. Projection here is the anterior tubercle. Projection here is the posterior tubercle and in connecting the two tubercles there is costotransverse bar. Various components in the transverse process. Then on the upper part of the pedical there is the notch which is referred to as superior vertebral notch. Superior vertebral notch is deeper as compared to that of the inferior vertebral notch for cervical vertebrae. Then the spinous process is biped. We can see the splitting of the spinous process. This gap is occupied by a ligament which is referred to as ligamentum nuke. These are various features of a typical cervical vertebrae. Let's see the features of the atypical cervical vertebrae. Here we can see two atypical cervical vertebrae. One is atlas and other is axis. Atlas is a ring like vertebrae. It doesn't have body. Its body has been migrated to the second cervical vertebrae which is represented by the odontode process or the dense of the axis. So for atlas vertebrae at times it becomes difficult to identify which part is superior, which part is inferior, which part is anterior, which part is posterior. So for that what we can do? We can see the superior aspect. This concave depression is a superior articular facet. It is concave for articulation with the occipital condyles. It is an ellipsoid variety of synovial joint. And the inferior articular facets if we see those will be circular. This part is referred to as the anterior arch of the atlas. This part is referred to as the posterior arch of the atlas. In this ring the anterior arch forms the one-third and posterior arch forms the two-third of the ring. That's how we can identify which is anterior and which is posterior. Then for axis vertebrae the most characteristic identification feature is the odontode process or the dense. And it has a very broad spinous process as compared to that of other cervical vertebrae. In the seventh cervical vertebrae how to differentiate it from the typical ones? You can see a long spinous process. This is the longest among all the spinous process which is referred to as vertebra prominence. And this will resemble that of the first thoracic vertebrae. So how to differentiate C7 from T1? C7 usually will have this foramen transversarian and T1 will have costal facets. Costal facets is the cardinal feature for thoracic vertebrae. So this was about all cervical vertebrae. And various applied aspects with respect to the cervical vertebrae include this. There is one applied aspect with respect to the anterior tubercle of the sixth cervical vertebrae which is referred to as casignax tubercle. It is the largest amongst all the anterior tubercles. And the common carotid artery is usually palpated against it. And that's why it is also referred to as carotid tubercle. Then this atlas may fuse with the occipital condyles. That clinical condition is referred to as occipitalization of the atlas. Then there may be cervical disc prolapse in between the two vertebrae. There is intervertebral disc which may prolapse and then compress upon the nerve roots which are exiting. That is referred to as cervical disc prolapse. Then there may be fusion of the cervical vertebrae in a clinical condition called as clipple field syndrome. This was also all about cervical vertebrae. Now let's cover the hyoid bone. Hyoid bone is the only bone in the body which doesn't articulate with any other bone. It is usually suspended by the stylohyoid ligament. Various parts of the hyoid bone are this is the body of the hyoid bone. This projection is the lesser corno of the hyoid bone. And this is the greater corno of the hyoid bone. What is the vertebral level of hyoid bone? It is C3 vertebra. And development of hyoid bone is very important you should be knowing. The upper half of the body and the lesser corno are these are derived from the second pharyngeal arch. In the lower half of the body and the greater cornoa they are derived from the third pharyngeal arch. Here we can see the lateral view of the hyoid bone. This is lesser cornoa, greater cornoa and body. There is one important applied anatomy with respect to the greater corno of the hyoid bone. The three anterior branches of external carotid artery we should be knowing the relations with respect to the greater cornoa. The facial artery is above the greater cornoa of hyoid bone. Lingual arteries at the level of greater cornoa of hyoid bone. And the superior thyroid artery is at a lower level with respect to the greater cornoa of the hyoid bone. And there is one medical legal importance with respect to the hyoid bone. The hyoid bone is fractured. It suggests that the death may be due to throttling or strangulation. Because when the death is due to hanging, hyoid bone usually does not get fractured. This is the last part of this session. The ossicles of the ear. This is the malleus. This is incis and this is steps. Various parts of these ossicles also we should be knowing. This is the head of the malleus. Below the head there is the neck of the malleus. This is anterior process. This lateral process. And this is the handle of the malleus. And for incis, this is the body of the incis. This is the short process of incis. This is the long process of the incis. This gives projection in the lower aspect that is referred to as the lenticular process. And for steps, this is the head of the steps. And there is anterior arch, posterior arch and foot plate. And the articulation between these three ossicles are also important. Between malleus and incis, the joint is impudo-malleolar joint. It is a saddle variety of synovial joint. And the joint between incis and steps, this is the ball and socket variety of synovial joint. So, all ossicles are present in the middle here. Development of these ossicles are also important. The malleus and the incis, they develop from the first pharyngeal arch. The steps, it develops from the second pharyngeal arch, except the foot plate. Foot plate arises from the otic capsule. Then the muscles attached to the ossicles, they should be knowing. Malleus gives attachment to a muscle that is tensor timpani muscle. And steps gives attachment to a muscle that is stapedius. So, this was about the ossicles of the year. So, we have covered all bones in the head and neck region. So, if you all have any doubts, you can ask in the comment section below. Thank you.