by Dr. Syed Irfan Qadeer(MS) Prof. and Head Department of Anatomy, Sardar Patel Dental College, Lucknow
Text of Anatomy of maxilla and mandible
1. Anatomy of Maxilla and Mandible By:- Dr. Syed Irfan Qadeer Prof. And Head, Department of Anatomy Sardar Patel Dental College, Lucknow.
2. Maxilla It is the second largest bone of the face It forms the upper jaw with the fellow of the opposite side It also contributes to the formation of 1. Floor of the nose and the orbit 2. Roof of the mouth 3. Lateral wall of the nose 4. Pterigopalatine and infratemporal fossae 5. Pterigomaxillary and infraorbital fissures 3. Anatomy of the maxilla The anatomy of the maxilla has two main parts: 1. Body(pyramidal shape) Anterior surface Posterior surface Orbital surface Nasal surface 2. Processes Zygomatic Frontal Alveolar Palatine 4. Anterior Surface: Incisive Fossa: Depressor septi nasi Orbicularis oris Canine fossa: Levator anguli oris Infraorbital foramen (above canine fossa) Infraorbital nerves and vessels Above sharp border between anterior and orbital surface: Levator labi superioris Nasal notch: Dilator Naris Ant Nasal Spine 5. Posterior Surface It is directed backwards and laterally It forms anterior wall of the infratemporal fossa Anterior and posterior surfaces are seperated by ridge which leads to the socket of 1st molar tooth Near the centre of posterior surface 2 to 3 openings of dental canal for posterior superior alveolar vessels and nerves At the lower end there is a raised maxillary tubrosity which is rough in the upper part of its medial end for tubercle of the palatine bone which has the attachment of superficial fibres of themedial pterigoid muscles Above this smooth surface which forms the boundry of the ptrigopalatine fossa is grooved for the maxillary nerve, this groove is contineous with the infra orbital groove 6. Orbital surface Smooth and triangular Medial border Notch: lacrimal notch Behind this it articulates with the Lacrimal Orbital plate of ethmoid Orbital process of palatine Posterior border: Smooth, rounded and it forms greater part of infraorbital fissure in middle infraorbital groove Anterior border: forms orbital margin ,infraorbital groove and canal; a little lateral to this is canalis sinuosus which passes in the anterior wall of the maxillary sinus and reaches in the nasal cavity and opens in the side of the nasal septum in front of incisive canal A little lateral to the lacrimal groove there is attachment of inferior oblique muscle of eveball 7. Nasal Surface In its upper posterior part there is a large maxillary hiatus which leads into the maxillary sinus In articulated skull this hiatus is completed by ethmoid and lacrimal bones Behind this there is a rough impression for the perpendicular plate of palatine bone Infront of maxillary hiatus there is a lacrimal groove More anteriorly concal crest for articulation with inferior nasal concha 8. Maxillary Sinus Large pyramidal cavity with its apex directed laterally towards the zygomatic process Base is towards the lateral wall of the nose In articulated skull it is reduced by Above Uncinate process of ethmoid Desending part of lacrimal bone Below: inferior nasal concha Behind: perpendicular plate of palatine It opens into the middle meatus of the nose usually by two openings one of which is closed by mucous membrane in living state Occasionally there are projections in the maxillary sinus from roof to anterior wall 9. Processes Zygomatic: it is rough and pyramidal Front:it is contineous with the anterior surface of body Behind(concave):in continuity of the posterior surface Above: articulates with zygomatic bone Below(arched border) which anterior and posterior surface of the body 10. Frontal Process: Lateral Surface: Vertical ridge (Lacrimal crest) Groove for the lacrimal sac Medial surface: It is rough and uneven and articulates with the ethmoid and also closes the anterior ethmoidal sinus below ethmoidal crest Upper end: Articulates with the frontal bone Anterior border with the nasal bone Posterior border with the lacrimal bone 11. Alveolar processes: It has thick arched border behind and contains sockets to receive roots of teeth which vary in size and depth Canine deepest Molar widest and subdivided into 3 minor sockets by septae Incisors and premolars single Occasionally incisors are divided into 2 sockes 12. Palatine Process: Thick strong horizontal Inferior surface is concave and presents numerous foramina for passage of nutrient vessels and contains depressions for lodgement of glands Groove for grater palatine Vessels and nerves Incisive fossa leads into the incisive canal Sometimes anterior and posterior incisive foramen for long sphenopalatine nerve which communicates with the greater palatine nerve Upper surface: forms the floor of the nasal cavity Lateral Border fuses with rest of the bone Posterior border fuses with the horizontal plate of the palatine 13. Muscles attached to maxilla 14. Muscles of face 15. Arterial supply 16. Maxillary Artery 17. Veinous drainage 18. Nerve Supply 19. Lymphatics 20. Age changes in Maxilla 21. Mandible Largest and strongest bone of the face Curved horizontal body; convex forwards It has two rami which project upward from posterior end of the body The body is horse shoe shaped 22. External Surface Faint ridge: symphisis menti Mental protuberance in the triangular area below sympisis menti Mental tubercle on each side of mental protruberance Mental foramen between premolar teeth Oblique line 23. Internal Surface Myelohyoid line Sub mandibular fossa Sub lingual fossa Genial tubercle Myelohyoid groove 24. Borders Upper boder: Sockets for the mandibular teeth are present Lower border(Base) presents a digastric fossa Ramus Lateral Surface Medial Surface Mandibular foramen canal Lingula- mylohyoid groove Inferior border is continuous with the angle of mandible Upper Border: Mandibular Notch 25. Arterial Supply of Maxilla and Mandible 26. Nerve supply of Mandible 27. Veinous drainage of Mandible 28. Processes: Condylar Coronoid Mandibular canal 29. Age changes in mandible 30. Applied Anatomy Muscle injuries: Its cause and effects Incisivus labii Superioris: During the exposure of the bone of premaxilla between the canines ,a mucoperiosteal flap reflection may detach the muscle and if the muscle gets damaged the the drooping of the septum and ala of the nose may occur 31. Mylohyoid muscle Surgical manupulation of the floor of the mouth may result in edematous swelling of the sublingual space (above the mylohyoid muscle )and submandibular space(below the mylohyoid muscle) Cellulitis of this sublingual space in quiet common however excessive bilateral cellulitis of the sublingual spaces may push the tongue backwards and compress the pharynx and may result in airway obstruction 32. Genoiglossus muscle During the elevationof the lingual mucosa before making an impression for a subperiosteal implant a portion of the muscle may be reflected from te genial tubercle, however if the muscle is completly detached from the tubercle it may lead to retrusion of the tongue and airway obstruction 33. Medial pterigoid The medial pterigoid muscle binds the pterigomandibular space medially ,during surgical procedures involving the area of pterigomandibular space infection may occour and may be dangerous due to its closed proximity to the pharyngeal space Surgical exposure of the tissue posterior to the maxillary tubrosity may also involve the medial pterigoid muscle as a part of the muscle originates from the maxillary tubrosity 34. Lateral pterigoid muscle The lateral pterigoid muscle fibres are placed in an angulated manner and because of this there may be pain in patients with a full arched subperiosteal implant or prosthetic splint 35. Mentalis muscle: Complete reflection of the mentalis muscle for the purpose of extension of a subperiosteal implant may result in a condition known as witchs chin There is failure of the mentalis muscle reattachment following the implantation. An external bandage is applied for four days to help in the reattachment of the muscle 36. Buccinator muscle: Myositis of the detached buccinator muscle in patients with subperiosteal implants may cause swelling and pain at the site of origin of the muscle 37. Nerve injuries Inferior alveolar nerve: The nerve may be damaged easily when making an incision or reflection of the mucosa in its area therefore position of the inferior dental canal in vertical and buccolingual dimension is of great importance during site preprations for implants 38. Lingual nerve The position of the nerve is lateral to the retromolar pad the incision should remain lateral to the pad and the mucosal reflection should be done with a periosteal elevator in constant contact with the bone to prevent injury to the nerve 39. Nerve to mylohyoid: The nerve lies in closed relation to the ramus of mandible hence it is prone to get damaged during surgical intervention 40. Long buccal nerve: When the ramus is accessed for the purpose of a block graft excision great care must be take to protect this nerve from injury 41. Injury to vessels Maxillary vessels: During the surgical orthognathic procedures the major nutrient artery of the maxilla are sometimes damaged, but the blood supply is maintained by anastamosis present in the soft palate 42. Thank You email@example.com