 What needs mentioning here is the patient's airway compromise associated with mandibular fractures. Fractures of bilateral subcondyle and bilateral parasymphysis may create an unstable situation for the tongue because the fracture segments tends to fall behind. So here there is a need for immediate consideration or intervention. Mandibulus, the largest and strongest of the facial bones which is basically a tubular long bone which is bent into a blunt V shape. It has an outer dense cortical bone and loose cancerous bone within. The cortical bone is thicker anteriorly and at the lower border whereas it weakens as it moves posteriorly. It becomes thinner. So it means that the mandible is stronger in the anterior region in the midline and weakens as it moves posteriorly. Even though the mandible is basically V shaped, it has been modified to four functional processes namely the angle the coronoid process, the condylar process and the alveolar process. Now let us discuss each part of the mandible in detail. The superior border is the alveolar process which contains the indentation. The inferior border is made up of thick cortical bone. The mandible has two surfaces the outer lateral surface and an inner medial surface. The body of mandible joins the ramus at angle. The two bodies on either side fuse at the center called the symphysis. At the symphysis there is a thickened cortical area which is known as mental prokuberance. Mental pharaman is present on either side of the mandible, either side on the lateral aspect of the mandible and it is present between the roots of the first and second primolors. An oblique ridge runs from just inferior to the mental pharaman posteriorly and superiorly to the ascending ramus. This is about the lateral aspect of mandible. Now coming to the inner surface. The inner cortical surface at the midline shows two pairs of bony prominences. Here you have two pairs of small bony prominence which is termed the genial tubercles. The genio-hyoid muscle originates from the inferior genial tubercle and the genioblossus muscle originates from the superior genio-genial tubercle. Then running horizontally backward is an oblique ridge which is called the mylohyoid line or mylohyoid ridge to which mylohyoid muscle is attached. Below the mylohyoid line is the submandibular fossa which lodges the submandibular gland and above is the sublingual fossa which lodges sublingual gland. The quadrilateral structure that you see here is the ramus of the mandible. The lateral surface is rough and thick at the angled region by the insertion of masseter muscle. As you can see in this diagram on the medial surface is the mandibular ferramen that continues downward and forward into the mandibular canal and transmits inferior alveolar nerve and vessels. Lingula is a medial bony projection at the opening of the mandibular ferramen to which spenomandibular ligament is attached. Mylohyoid line is an extension from this lingula. Mylohyoid line extends from the tip of lingula downward and forward on the medial aspect of mandible. Below the mylohyoid line in the ramel area you can see rough surface here. This is due to the insertion of medial tergoid. So you have attachment of medial tergoid on the medial aspect of ramus in the inferior part and masseter on the lateral aspect of the ramus. This is a notch. You can see a notch over here. This is found at the superior edge of the ramus. It is called the mandibular notch. It is bounded by two processes. Coronoid process anteriorly and condylar process posteriorly. The fan shaped temporalis muscle attaches to the tip of the coronoid here. The temporalis attaches to the tip of the coronoid process and the attachment of lateral tergoid muscle is at the anterior portion of the neck of the condyle. So this is the condylar head. This is the this stalk is called the neck of the condyle and on the anterior aspect of the neck of the condyle you have a small depression called the tergoid fovea to which lateral tergoid muscle attaches. A detailed description of condyle head anatomy as well as its fracture management shall be discussed separately in subsequent lectures. Now moving on to one of the most complicated regions of mandible in terms of both anatomy and management that is the angle. After condyle angle region is the communist site of mandibular fracture. What could be the reasons one could think of? The anatomy of the angle itself will explain it. Angle is a junction and the junction or a joint is always weaker when compared to the adjoining parts. Angle is a junction formed by the adjoining, ramus and body. Every bone has a specific pattern of calcification lines. In case of mandible the direction of calcification suddenly changes from horizontal at the body to vertical at the ramus and the transition happens at the angle region. Thus angle has a comparatively thinner cross section than most of the other areas of mandible. In addition presence of wisdom tooth which could be an erupted or an unerupted one. Presence of inferior alveolar nerve canal and constant opposing muscle actions of the elevators and depressors make angle a difficult area in fracture management. Mantibulus one bone whose muscle attachments have a continuous function beat mastication speech facial expressions swallowing yawning so you cannot expect the fracture to remain still once it has occurred. Displacement is a very common feature of a fracture and it is important to understand the action of each muscle on a fracture. The first group of muscles is formed by the supra hyoid muscles which exerts a force in the posterior medial and inferior direction. So, if there is a fracture segment in the anterior mandible it is displaced inward backward and downward direction as you can see in this diagram. The next important muscle group is the tergomasic sling. You know that the ramus has attachments to massacre muscle on the external surface and medial tergoid on the internal surface. Therefore at the most posterior inferior aspect of the ramus there is a tendon or a sling which is formed by both the masseter and the medial tergoid which is called the tergomasic sling. So, in case of an angled fracture it is this muscle action that causes the posterior fragment to move in a supido medial and anterior direction. So, if there is a fracture at the angled region like this, imagine there is a fracture like this. In this case the segment containing the condyle is called the posterior segment and the segment containing the dentition is the anterior segment. Therefore, the tergomasic sling will tend to displace or move the fracture in a supido medial and anterior direction. This is the superior upward medial means inward and forward direction. The next muscle of concern is the temporalis. You know that the temporalis has an elevating and protruding action temporalis is attached to the tip of the coronal process. Therefore, in a fracture it tends to displace the segment in a posterior and superior direction that is backward and upward. Similarly, lateral tergoid also has two sets of actions each produced by the two separate components of lateral tergoid. It has an internal and an external component. The internal component is responsible for the anterior medial displacement anterior medial displacement of the condylar head in a supido direction. Both the components move the segment in anterior and medial direction but the internal component moves the condylar head in a superior direction and the external component in an inferior direction. The direction of the fracture at the angle can vary due to various peculiarities of the angle discussed earlier. Here you need to understand the terms favorable and unfavorable in context of mandibular fractures. If the direction or angulation of a fracture is such that it can resist the displacement of the posterior segment due to muscle actions then the condition of the fracture is favorable. That means if this is the fracture and if the posterior segment can resist its upward pull by the tergomacetric sling then the condition of the fracture is favorable. In the previous section we have seen the action of different muscles on a fracture. So keeping the same in mind we will now have a look at the horizontal and vertical favorability of mandibular angle fractures. This diagram shows the horizontal viewing of a fracture and this diagram shows the vertical viewing. Here the terms horizontal or vertical are defined from the viewpoint of the observer. Hence it is a traditional but not very practical terms. Thus a horizontal favorable fracture extends from the upper border downward and forward. This is the direction of a horizontally favorable fracture. This pattern of fracture is termed favorable because of the locking effect at the fracture side. The locking effect is produced by the anterior segment. So when the tergomacetric sling tries to pull the posterior segment upward it is locked at this region or at the fracture side by the anterior segment hence it is termed favorable fracture. Whereas in a horizontally unfavorable fracture the fracture line extends downward and backward. Unlike in a favorable condition here the fracture line extends downward and backward and thus here the locking effect is absent. The tergomacetric sling can freely pull the posterior segment superiorly. So this is how a horizontally favorable and unfavorable fracture look like. Likewise a vertically favorable fracture runs from the buckle plate posteriorly and medially. Here also you can appreciate the locking effect at the fracture side. Whereas in a vertically unfavorable fracture the fracture runs from the buckle plate anteriorly and medially. It moves forward and inward. There is no locking effect present here and this enables unopposed action of the tergomacetric sling thus displacing the posterior segment. One more thing that needs mentioning here is the patient's airway compromise associated with mandibular fractures. Fractures of bilateral subcontile and bilateral para-symphysis may create an unstable situation for the tongue because the fracture segments tends to fall behind. So here there is a need for immediate consideration or intervention. To sum up it's been told that mandible is the strongest of the facial bones but still mandibular fractures occur twice as often as mid-face fractures. The reason is being the unique osteology of mandible and the various muscle attachments that causes fracture displacement. Another reason is the presence of dentation. The socket is a weak zone especially if the teeth are impacted or unirrupted. So does it make children more susceptible to mandibular fractures? Actually not because a child's bone is more flexible and resilient. Therefore the incidence of a complete fracture is lesser in children when compared to adults. So that's all about the basics of mandibular fractures. We shall be discussing the management in detail in the next lecture. Thank you.