Innervation of teeth

(Trigeminal nerve) & Innervation of teeth by DR.Mahmoud Ashraf

1. Innervation Of The Teeth Trigeminal Nerve &

2. Cranial Nerves

3. Trigeminal Nerve The fifth (V) cranial nerve &the largest of the twelve cranial nerves. Provide among other functions sensory innervation from teeth, bone, and soft tissues of the oral cavity. It is composed of a small motor root and a considerably larger (tripartite) sensory root.

4. Trigeminal Nerve -Cont’d- The three major branches of the trigeminal nerve The ophthalmic nerve (V 1 ) –Sensory- The maxillary nerve (V 2 ) -Sensory- The mandibular nerve (V 3 ) –Mixed-

5. Trigeminal Nerve -Cont’d- The 3 branches of the sensory root supply : the skin of the entire face. the mucous membrane of the cranial viscera. the mucous membrane of the oral cavity and teeth, except for the pharynx and base of the tongue.

6. Trigeminal Nerve -Cont’d- Motor fibers of the trigeminal nerve supply the following muscles: - Masticatory . Masseter Temporalis Pterygoideus medialis Pterygoideus lateralis - Mylohyoid . -Anterior belly of the digastric . -Tensor tympani. -Tensor veli palatini .

7. Ophthalmic nerve (V1) It is purely sensory and is the smallest of the three divisions. The ophthalmic division (V1) travels anteriorly in the lateral wall of the cavernous sinus to the medial part of the superior orbital fissure, through which it exits the skull into the orbit. branches: nasociliary , frontal , and lacrimal nerves.

8. Ophthalmic nerve (V1) It supplies :- The eyeball Conjunctiva Lacrimal gland Parts of the mucous membrane of the nose and paranasal sinuses. The skin of the forehead upper eyelids, and nose. Note: When the ophthalmic nerve (V1) is paralyzed, the ocular conjunctiva becomes insensitive to touch.

9. Ophthalmic nerve (V1)

10. Maxillary nerve (V2) Intermediate in size between ophthalmic and mandibular divisions. it is purely sensory in function. The maxillary division (V2) travels anteriorly and downward to exit the cranium through the foramen rotundum into the upper portion of the pterygopalatine fossa .

11. Maxillary nerve (V2) As it crosses the pterygopalatine fossa , it gives off branches to the sphenopalatine ganglion , the posterior superior alveolar nerve , and the zygomatic branches . It then angles laterally in a groove on the posterior surface of the maxilla, entering the orbit through the inferior orbital fissure . Within the orbit , it occupies the infraorbital groove and becomes the infraorbital nerve , which courses anteriorly into the infraorbital canal.

12. Maxillary nerve (V2)

13. (V2) branches The maxillary division gives off branches in four regions: within the cranium -> “ middle meningeal nerve ”. in the pterygopalatine fossa . in the infraorbital canal. on the face.

14. Branches from the Pterygopalatine ganglion 1- The orbital branches supply the periosteum of the orbit. 2- The nasal branches - the nasopalatine nerve , which passes across the roof of the nasal cavity downward and forward, It enters incisive canal , through which it passes into oral cavity via the incisive foramen . -provide sensation to the palatal mucosa in the region of the premaxilla (canines through central incisors)

15. Branches from the Pterygopalatine ganglion 3- The palatine branches :- A- The greater (or anterior) palatine nerve. emerging on the hard palate through the greater palatine foramen (which is usually located about 1 cm toward the palatal midline, just distal to the second molar). Or may be located 3 to 4 mm in front of the posterior border of the hard palate. supplying sensory innervation to the palatal soft tissues and bone as far anterior as the first premolar, where it communicates with terminal fibers of the nasopalatine nerve

16. Branches from the Pterygopalatine ganglion 3- The palatine branches :- B- The lesser (middle and posterior) palatine nerves. provides sensory innervation the soft palate.

17. 1 .Posterior superior alveolar branches. 2 . infraorbital nerve. 3 . Maxillary nerve. 4 . foramen rotundum. 5 . greater palatine nerve. 6 . nasopalatine nerve.

18. Branches from the Pterygopalatine ganglion 4- The pharyngeal branch leaves the posterior part of the pterygopalatine ganglion, passes through the pharyngeal canal, and is distributed to the mucous membrane of the nasal part of the pharynx.

19. Branches within the Pterygopalatine Fossa 1- The pterygopalatine nerves ( Ganglionic branches) Are two short trunks that unite in the pterygopalatine ganglion serve as a communication between the pterygopalatine ganglion and the maxillary nerve. Postganglionic secretomotor fibers from the pterygopalatine ganglion pass through these nerves and back along V2 to the zygomatic nerve, through which they are routed to the lacrimal nerve and the lacrimal gland.

20. Branches within the Pterygopalatine Fossa 2-The Zygomatic branch :- Travels anteriorly , entering the orbit through the inferior orbital fissure, where it divides into two nerves. the zygomaticotemporal supplying sensory innervation to the skin on the side of the forehead. the zygomaticofacial supplying the skin on the prominence of the cheek Note: the zygomatic nerve sends a branch that communicates with the lacrimal nerve of the ophthalmic division. This branch carries secretory fibers from the sphenopalatine ganglion to the lacrimal gland.

21. Branches within the Pterygopalatine Fossa 3- The posterior superior alveolar (PSA) (PSA) nerve descends from the main trunk of the maxillary division in the pterygopalatine fossa just before the maxillary division enters the infraorbital canal. they reach the inferior temporal (posterior) surface of the maxilla. When two trunks are present, one remains external to the bone, continuing downward on the posterior surface of the maxilla to provide sensory innervation to the buccal gingiva in the maxillary molar region and adjacent facial mucosal surfaces.

22. Branches within the Pterygopalatine Fossa 3- The posterior superior alveolar (PSA) the other branch enters into the maxilla (along with a branch of the internal maxillary artery) through the PSA canal to travel down the posterior or posterolateral wall of the maxillary sinus, providing sensory innervation to the mucous membrane of the sinus . Continuing downward, this second branch of the PSA nerve provides sensory innervation to the alveoli, periodontal ligaments, and pulpal tissues of the maxillary third, second, and first molars (with the exception [in 28% of patients] of the mesiobuccal root of the first molar).

23. 1. Maxillary Nerve. 2. posterior superior alveolar branches.

24. Branches in the Infraorbital Canal Within the infraorbital canal, the maxillary division (V2) “ infraorbital nerve” gives off two branches of significance in dentistry: The middle superior alveolar nerve. The Anterior superior alveolar nerve.

25. The middle superior alveolar nerve Branches to form a part of the superior dental plexus, composed of the posterior, middle, and anterior superior alveolar nerves. The MSA nerve provides sensory innervation to the two maxillary premolars and, perhaps, to the mesiobuccal root of the first molar and periodontal tissues , buccal soft tissue , and bone in the premolar region . Note : Traditionally it has been stated that the MSA nerve is absent in 30% to 54% of individuals.

26. The Anterior superior alveolar nerve Branch is given off the infraorbital nerve (V2) approximately 6 to 10 mm before the latter exits from the infraorbital foramen. Descending within the anterior wall of the maxillary sinus, it provides pulpal innervation to the central and lateral incisors and the canine , and sensory innervation to the periodontal tissues , buccal bone , and mucous membranes of these teeth. Note : In persons without an MSA nerve, the ASA nerve frequently provides sensory innervation to the premolars and occasionally to the mesiobuccal root of the first molar.

27. 1. Branches of the ASA nerve. 2. superior dental plexus. 3. dental branches. 4. interdental and interradicular branches.

28. Branches on the face The infraorbital nerve emerges through the infraorbital foramen onto the face to divide into its terminal branches: - inferior palpebral nerve : provide sensory supply to the skin of the lower eyelid. External (lateral) nasal nerve: provide sensory innervation to the skin on the lateral aspect of the nose. superior labial nerve : provide sensory innervation to the skin and mucous membranes of the upper lip.

29. Mandibular nerve (V3) The mandibular division (V3) travels almost directly downward to exit the skull, along with the small sensory and large motor root, through the foramen ovale . These two roots then intermingle, forming one nerve trunk that remains undivided for only 2 to 3 mm before it splits into a small anterior and a large posterior division.

30. Mandibular nerve (V3) The mandibular division (V3)branches 1- Trunk. nervus spinosus ( meningeal branch of the mandibular nerve). It reenters the cranium through the foramen spinosum to supply the dura mater and mastoid air cells . medial pterygoid nerve. motor nerve to the medial pterygoid muscle. tensor veli palatini . tensor tympani.

31. Mandibular nerve (V3) The mandibular division (V3)branches 2- Branches from the Anterior Division:- A- buccal nerve (long buccal ) or ( buccinator nerve) sensory innervation to the mucous membrane of the cheek and the buccal mucous membrane of the mandibular molars B- deep temporal nerves. C- Massetric nerve . D- lateral pterygoid nerves. Motor innervation to the muscles of mastication

32. Mandibular nerve (V3) The mandibular division (V3)branches 3- Branches of the Posterior Division. A- Auriculotemporal nerve : sensory, secretory , and vasomotor fibers to the parotid gland ( the secretomotor fibers are from the otic ganglion)

33. Branches of the Posterior Division. B- The lingual nerve : It passes downward medial to the lateral pterygoid muscle and, as it descends, lies between the ramus and the medial pterygoid muscle in the pterygomandibular space. It runs anterior and medial to the inferior alveolar nerve, whose path it parallels.

34. Branches of the Posterior Division. B- The lingual nerve : The lingual nerve is the sensory tract to the anterior two thirds of the tongue . It provides general sensation for this region. whereas the chorda tympani (a branch of the facial nerve) supplies fibers for gustation (taste). provides sensory innervation to the mucous membranes of the floor of the mouth and the gingiva on the lingual of the mandible

35. Branches of the Posterior Division. C- The inferior alveolar nerve : The largest branch of the mandibular division. It descends medial to the lateral pterygoid muscle and lateroposterior to the lingual nerve. enters the mandibular canal at the level of the mandibular foramen between the sphenomandibular ligament and the medial surface of the mandibular ramus .

36. Branches of the Posterior Division. C- The inferior alveolar nerve : travel anteriorly in the mandibular canal as far forward as the mental foramen, where the nerve divides into its terminal branches: the incisive nerve the mental nerve. Note : Double inferior alveolar nerves and mandibular canals were evident in 0.95% of studied cases. (Extremely rare)

37. Branches of the Posterior Division. C- The inferior alveolar nerve : The dental plexus serves the mandibular posterior teeth , entering through their apices and providing pulpal innervation . The incisive nerve remains within the mandibular canal and forms a nerve plexus that innervates the pulpal tissues of the mandibular first premolar, canine, and incisors via the dental branches. The mental nerve exits the canal through the mental foramen and divides into three branches that innervate the skin of the chin and the skin and mucous membrane of the lower lip.

38. Branches of the Posterior Division. D- The mylohyoid nerve Branches from the inferior alveolar nerve before entry of the latter into the mandibular canal. The mylohyoid is a mixed nerve :- 1- being motor to the mylohyoid muscle and the anterior belly of the digastric . 2- contain sensory fibers that supply the skin on the inferior and anterior surfaces of the mental protuberance Note : May provide sensory innervation to the mandibular incisors or the mandibular molars in some persons, usually the mesial root of the mandibular first molar.

39. Innervtion Of Teeth References Handbook of Local Anesthesia , 6 th Edition 2013 by Stanley F. Malamed , DDS. Local Anesthesia for Dental Professionals, 2 nd Edition by Kathy bassett