 Hello everyone, welcome back to another session in the strand more. So we are continuing our danger bearing areas So last session we finished the same in maxilla. So this session is about mandible. So we'll go with the same Structures that is the limiting structure supporting structures and relief areas of mandible So we have limiting structures label freenam label vestibule buckle freenam buckle vestibule Linguel freenam alveolo lingual sulcus retromolar pad and tarigomandibular raffae It's almost like the maxillary Structures, but a little different. We have a retromolar pad and Alveolo lingual sulcus and tarigomandibular raffae in limiting structures of mandible So let's see the details of danger bearing areas in mandible. So the first one is labial freenam So label freenam is a fold of mucus membrane at the median line Okay, so this is a label freenam and It divides the label vestibule into right and left that is two halves. So this is a label vestibule So this label freenam Divides into two halves right and left halves and it consists of band of fibrous Connected tissue and helps to attach orbicularis oris muscle. Okay This is a shorter and wider than the maxillary label freenam and While taking impression We should give sufficient relief Without compromising the peripheral seal So the freenam is quite sensitive and active and the danger must be fitted carefully around it to maintain a Seal without causing soreness So that is a label freenam. Now we have labial vestibule. So it runs from the buckle freenam So this is a buckle freenam on right and left side. So it runs from buckle freenam On the left side to the right side and it is divided into left and right by as I mentioned by label freenam So fibers of orbicularis oris in Cicivos and mentalis are inserted near the crest of the ridge So this mentalis muscle is an active muscle So while taking impression the extent of the danger We should think that the extent of the danger flange in this region is often limited Because of this muscle action because there are muscle fibers which are inserted close to the Crest of the ridge. So thick danger flanges May cause dislodgement of the danger When patient Opens the mouth very wide. So we need to think of those muscles which are seen in this region such as orbicularis oris mentalis and in Cicivos muscle. So whenever there is muscle action we need to Think of the dislodgement. So muscle action should not be hampered while taking impression or creating the danger So the next one we have buckle freenam. So we finished label freenam and label vestibule Now we have the buckle freenam. Okay So buckle freenam forms a dividing line between the label and buckle vestibule. So this is a label vestibule and this is buckle vestibule So it can be U-shaped or V-shaped and it overlies the muscle depressor and coli oris Okay So you need to understand the muscle action in detail to have a very good picture of the danger bearing areas. So muscle should be taken care while taking impression. Otherwise there will be dislodgement So depressor, an coli oris is present here And also fibers of buccinator muscle attached to the freenam So this relief of buckle freenam is very important because if it is not relieved there will be displacement of the danger because of the muscle action Now we have the buckle vestibule. Okay. It's the buckle vestibule. It extends from the buckle freenam to the retromolar pad So this is a retromolar pad area. So it extends from buckle freenam to retromolar pad on both sides and it is Nearly right angle to the biting force. Okay. So this area is right angle to the biting force This is what is similar to the heart palette primary stress bearing area in maxilla. So Extent of this buckle vestibule is influenced by the muscle buccinator Which extends from the modulus Anteriorly to terigo mandibular raffae. So modulus. We already studied modulus is an intersection area where many muscles are getting attached Near the angle of mouth. So from that area to the terigo mandibular raffae That is the extension. So terigo mandibular raffae will be here And the masseter muscle which contracts under heavy closing force and pushes inwards Against the buccinator muscle to produce a massetric notch in the distro buckle. So massetric notch will be coming here Border of the lower denture. So how it is forming? It is by the action of Masseter and buccinator when this masseter muscle contracts under heavy closing force And pushes inwards against the buccinator muscle Creates a massetric notch And what is the clinical significance? So this distro buckle border of the lower denture should accommodate the contracting masseter force That is a muscle force so that the denture does not dislodge during heavy closing force So that is why we asking the patient to the mandibular movements opening and closing the moments in order to uh record the massetric notch properly and to Balance in a harm or keeping in harmony of this contracting forces that is a massetric and buccinator muscle forces Next we have The lingual freedom lingual freedom This is one lingual freedom. It is a fold of mucus membrane Existing when the tip of the tongue is elevated and it overlies the muscle genioglossus Okay, so there'll be genioglossus muscle here Which takes the origin from superior geniotubical. So hope you remember the geniotubical superior and inferior one on the inner side of midline of mandible And the anterior region of lingual flange is called sublingual crescent area So there should be always a crescent shaped area of our lower denture near the lingual freedom and The relief of lingual freedom should be registered during our function A short freedom is called tongue tie. So hope you heard this word Tongue tie And it should be corrected if it affects the stability of the denture. Tongue tie should be Relieved by a surgical procedure To avoid the dislodgement of denture in muscles action. That is the tongue muscles and the other muscle action And the next part is Albulolingual sulcus So albulolingual sulcus is a space between the tongue. So here we can imagine a tongue So it is a space between tongue and the residual ridge So it extends from lingual freedom to the retro myelohyd curtain So it here it is a retro myelohyd curtain And it has basically three regions anterior region middle region and posterior region. So anterior region extends from lingual freedom Back to where myelohyd muscle curves above the level of sulcus. That is a pre myelohyd forza Then the middle region extends from pre myelohyd forza to the distal end of Myelohyd ridge. So myelohyd ridge will be here where the myelohyd muscle is attached and the posterior region Here the flange passes into the retro myelohyd forza So retro myelohyd forza is not able to shown in this type of picture. It should be a side view picture. This is a top view picture And It has a typical S shaped form The anterior middle and the posterior region And the clinical significance is the lingual flange of lower denger will be shot anteriorly than posteriorly and In the middle region it slopes medially towards the tongue So that is the importance of alveolo lingual sulcus And next we have the retro myelohyd space. We talked about retro myelohyd space. It is a space which lies at the distal end of alveolo lingual sulcus. Okay, so the distal end of alveolo lingual sulcus here we have a space known as alveolo lingual sulcus. It is bounded anterior tonsillar pillar Anteaterly by tonsillar pillar posteriorly by the retro myelohyd curtain. So this is the terminal end of this alveolo lingual sulcus And What is that? Retro myelohyd curtain So retro myelohyd curtain is nothing but Formed posteriorly by the superior constrictor muscle laterally by the mandible And trigomandibular raffae anteriorly by the lingual tuberosity and inferiorly by the myelohyd muscle. Okay So there are many structures which is forming the retro myelohyd curtain Posteriorly by the superior constrictor muscle. Okay laterally by the mandible and trigomandibular raffae anteriorly by the lingual tuberosity and inferiorly by the myelohyd muscle Now the structure We're moving on to the retro myelopad. So it is a non keratinized triangular Peer-shaped pair of tissues at the distal end of lower ridge So the submucosa contains glandular tissues fibers of buccinator superior constrictor muscle trigomandibular raffae terminal part of the tendon of temporalis And the retromolar papillae There's a pear-shaped area just anterior to retromolar pad. Okay. So this is a retromolar papillae It is a dense fibrous connective tissue area. Okay. So in retromolar pad we have structures The superior constrictor muscle, trigomandibular raffae and the temporalis So the clinical significance is the distal end of denger pad should cover the two-third of retromolar pad. Okay Not completely but the two-third of retromolar pad And it provides a peripheral posterior seal for the lower denger It is almost like our pps post palatal seal area in mandibular denger We have retromolar pad which gives a posterior peripheral seal But we should cover only the two-third of the retromolar pad The last structure is trigomandibular raffae. So trigomandibular raffae is very vital in taking lower denger or lower arch impression Because it does a tenderness insertion of two muscles. So like I told when wherever the muscle action is there We should take very much precaution So it erases from this trigomandibular raffae erases from hamler process of the medial trigoid And gets attached to the myelohydrage. So it is coming. I'm getting attached towards the myelohydrage So it has superior constrictor muscle posterior laterally and buccinator anteriorly anterior laterally. So posterior laterally and anterior laterally here we have Superior constrictor and here we have buccinator So it is very prominent in some patients and arch-like relief must be provided on the denger So relief should be there. Otherwise this buccinator and superior constrictor action will dislodge the denger Now let's move to the supporting structures. So supporting structures are The first one is Buckle shelf area and the residual alveolar ridge. Okay So supporting structures are Buckle shelf area and residual alveolar ridge In maxilla we learn primary stress bearing area secondary stress bearing area primary was the heart palate and the Slops of this residual alveolar ridge again the rugae maxillary tuberosity alveolar tubercle begins the secondary stress bearing area So buckle shelf area is the area between buckle freedom and anterior border of Masseter muscle. So this is the buckle freedom And the masseter muscle will be coming here We learned about massetric nodes from this area to this area. That is a buckle shelf area So the boundaries includes Medially the crest of alveolar ridge medially the crest of alveolar ridge distally the retromolla pad And laterally the external oblique ridge. Okay. So laterally external oblique ridge medially The crest of ridge and distally the retromolla pad So the mucous membrane covering the buckle shelf area is loosely attached less keratinized and contain thick sub mucosa So buckle shelf area is a very important short note So the clinical significance that it lies at right angle to the vertical or crucial forces And this makes it suitable for primary stress bearing area of lower tension And the next one is residual alveolar ridge. So the edgeless mandible may become flat due to resorption Which results into outward inclination and progressively widening of the mandible And also in maxilla the resorption is upward upward and inward And making it smaller. So it is the reason why the edgeless patients to have a prognetic appearance Because this is maxilla it is going upward and inward whereas the mandible resorption is happening Which gives a widening of the mandible because of the outward inclination Okay So the slopes of this residual alveolar ridge have thin plate of cortical bone So the slopes of these ridge act at an acute ankle to this occlusion forces Okay, so it can be a secondary stress bearing area Because it is the Area which bears a master category force at an ankle not perpendicular So perpendicularly on the buckle shelf area. So it is known as primary stress bearing area So since the crest of the ridge has cancels bone. It is not favorable as primary stress bearing area So clinical significance as any movable soft tissue overlying the ridge should not be compressed while making impression Okay, now let's move to the Relief areas So they are mental foramen genial tubical Myla hydrige and mandibular thorac So mental foramen it is uh Between the first and second premolar region due to the ridge resorption It may like close to the ridge So it should be relieved and in these areas There are nerve passing It might compress the nerves and It might create a problem in denger varying so Again the parasitia problem that is the numbness of lower lip will be there If it is not properly relieved and the denger keeps on pressing on this nerves So mental foramen should be Relieved the second one is a genial tubical So genio tubical are a pair of dense prominence at the inferior border of the mandible at the lingual midline Which represents muscle attachment of genio gloses and genio hyoid muscle So they only become relevant in the denger when there is excessive resorption of the residual ridge So if you have a adequate bone height, it will not be a problem But if there is a resorption We need to relieve the genio tubical to avoid the action of genio gloses and genio hyoid muscle Now we have the myla hydrige. So myla hydrige will be here It's a bony prominence along the lingual aspect of mandible and soft tissue usually hides the sharpness of this myla hydrige And tidierly this ridge With myla hydrige muscle is close to the inferior surface of mandible posteriorly it often Fleshes with residual ridge So the mucus membrane overlaying the sharp or irregular myla hydrige needs to be relieved because the denger ways might easily traumatize it So we need to relieve myla hydrige in order to avoid the Traumatic effect on this by the denger base And the mandibular torre just like the palatal torre So these bony prominence which are found by actually on the lingual side near the premola region So it should be relieved or it can be surgically removed before taking the impression So That's all about the denger bearing areas in mandible So we finish the entire session and both in maxilland mandible So as our knowledge of anatomical landmarks of denger bearing areas are very essential To get the objective of a proper denger making So Fabrication of any complete ensure with maximum retention stability and support with preservation of underlying structures With a minimum post insertion problem Requires a sound knowledge of all the anatomical landmarks that is the limiting structures supporting structures and relief areas of both maxilland mandible So hope you understood the concept of denger bearing areas in mandible So it was a lengthy session. We had maxilland mandible So on an exam point of view, we may have many questions from this chapter or this session It could be a short note short essay or long essay So hope you understood this i'll come up with a new topic in prosodontics. Thank you