Nerves OS1 PDF

Welcome to The Oral & Maxillofacial Surgery Department  Oral & Maxillofacial Surgery ◼ OMFS is the specialty of dentistry concerned with the diagnosis, surgical & adjunctive treatment of diseases, injuries & defects involving both the functional & esthetic aspects of the hard...

Welcome to The Oral & Maxillofacial Surgery Department  Oral & Maxillofacial Surgery ◼ OMFS is the specialty of dentistry concerned with the diagnosis, surgical & adjunctive treatment of diseases, injuries & defects involving both the functional & esthetic aspects of the hard & soft tissues of the oral & maxillofacial region ( face, mouth, teeth & jaws) ◼ It is often considered as a Bridge Between Medicine & Dentistry.  Lecture Topics for OSI ◼ Trigeminal & Maxillary Nerves ◼ Mandibular Nerve ◼ Max. Anesthetic techniques ◼ Mand. Anesthetic techniques ◼ Pain Pathways. ◼ Pharmacology of Local Anesthesia. ◼ Complications of Local Anesthesia.  Anatomical Considerations By Dr. Essam M. Ashour BDS 1992, MD 2000, Alexandria University PHD 2007, Cairo University Associate Professor of Oral & Maxillofacial Surgery, Oct. 6 University Head of Oral & Maxillofacial Surgery Unit, Oct. 6 University Hospital The Trigeminal Nerve CN Ⅴ Cranial Olfactory Nerves (I) Optic (II) Oculomotor (III) Trochlear (IV) Trigeminal (V) Abducent (VI) Facial (VII) Vestibulocochlear (VIII) Glossopharyngeal (IX) & Vagus (X) Hypoglossal (XII)  The Trigeminal Nerve (5th) ◼ The largest cranial nerve. ◼ The Trigeminal nerve transmits sensations from the skin of the anterior part of the head, the oral, nasal & paranasal cavities, the teeth and the meninges. ◼ Mixed, mainly sensory with a small motor root. Both roots arise from the pons & M.O The sensory fibers arise from the Trigeminal (Gasserian) ganglion found in the MCF in a a depression called Cavum Trigeminalis ◼ V1 Ophthalmic, V2 Maxillary, V3 Mandibular divisions Distribution of the Trigeminal Nerve Distribution of the Trigeminal Nerve Trigeminal Somatic Sensory Area  THE OPHTHALMIC NERVE ◼ Functions: ◼ The ophthalmic nerve transmits sensory fibres from the: ◼ Eyeball, the skin of the upper face and anterior scalp, the lining of the upper part of the nasal cavity and air cells, and the meninges of the anterior cranial fossa. Origin, course and branches ◼ Originates from trigeminal ganglion in middle cranial fossa then passes anteriorly through lateral wall of cavernous sinus. ◼ Divides into three branches: frontal (largest), nasociliary and lacrimal (smallest) which pass through superior orbital fissure to the orbit.  Frontal nerve ◼ Passes immediately below frontal bone and divides into: 1. Supraorbital (larger, lateral) ▪ Supraorbital nerve in the supraorbital notch (with branch of ophthalmic artery) turns up to supply skin of forehead and scalp (back to vertex). 2. Supratrochlear (medial) nerves. ▪ Supratrochlear n supplies the Frontal sinus & a small area of skin above the nasal bridge.  Nasociliary nerve ◼ It supplies the eyeball, upper part of nasal cavity, and ethmoidal and sphenoidal air cells, anterior nasal skin, and meninges. ◼ Branches: ◼ 1. Long and short cilliary nerves to the eyeball to innervate ocular structures including the cornea. Short ciliary nerves contain parasympathetic impulses from ciliary ganglion. Long and short ciliary nerves also contain sympathetic fibres (Pupillary dilatation & constriction)  Nasociliary nerve 2. Anterior ethmoidal nerve ◼ Gives sensory fibres to meninges of anterior cranial fossa then enters the nasal cavity to supply the upper part of the nasal cavity, and the sphenoid and ethmoidal air sinuses. ◼ Continues as the external nasal nerve which supplies cutaneous sensation to the anterior aspect and tip of nose.  Lacrimal nerve ◼ It supplies the lacrimal gland, and small area of adjacent skin and conjunctiva. ◼ It receives postganglionic parasympathetic secretomotor fibres from the pterygopalatine ganglion conveyed through the zygomatic branch of the Maxillary n to supply the Lacrimal gland. The Maxillary Nerve V2  The Maxillary Nerve V2 ◼ Course : ◼ The Maxillary n is the second division of the Trigeminal nerve. It is a pure sensory nerve. ◼ It is intermediate in size & position.. ◼ Before it leaves the cranial cavity, it runs on the lower part of the lateral wall of the cavernous sinus. The Maxillary Nerve V2  The Maxillary Nerve V2 ◼ It leaves the middle cranial fossa though Foramen Rotundum to enter the pterygopalatine or sphenopalatine fossa where it gives two small sensory roots which suspend the Sphenopalatine ganglion in the pterygopalatine fossa. ◼ Then it passes through the pterygomaxillary fissure to enter the infratemporal fossa for a short distance, after which it enters the Orbital cavity by passing through the inferior orbital fissure where it is called the Infraorbital n which is considered the continuation of the Maxillary nerve. The Maxillary Nerve V2  The Maxillary Nerve V2 ◼ In the orbit, the Infraorbital nerve runs on the floor of the orbit in the infraorbital groove, then inside the infraorbital canal then comes out on the face through the infraorbital foramen where it gives off its terminal branches. ◼ The Infraorbital N is considered the continuation of the Maxillary nerve. The Maxillary Nerve V2 Branches of the Maxillary nerve In the Middle cranial fossa Meningeal branch which supplies sensory fibres to the meninges of the middle cranial fossa. Branches of the Maxillary nerve In the Sphenopalatine Fossa Two sensory roots which suspend the Sphenopalatine ganglion to the maxillary nerve.  Branches of the Maxillary nerve ◼ In the Infratemporal Fossa I. Zygomatic Nerve It enters the orbit by passing through the inferior orbital fissure to run on the lateral wall of the orbit then divides into 2 branches : a. a. Zygomatico-facial N which supplies the skin over the prpminence of the cheek (zygomatic bone) b. b. Zygomatico-temporal N which supplies the skin of the temporal area of the scalp. c. C. It carries postganglionic parasympathetic secretomotor n fibers to join the lacrimal branch of the ophthalmic n to supply secretomotor innervation to the Lacrimal gland. Branches of the Maxillary nerve II. Infraorbital Nerve It enters the orbit by passing through the inferior orbital fissure to run on the floor of the orbit in the infraorbital groove then through the infraorbital canal to come out on the face through the infraorbital foramen. Branches of the Maxillary nerve Branches of the Infraorbital Nerve : 1. Middle Superior Alveolar N It takes origin from the infraorbital n while passing in the infraorbital groove. It supplies the pulps & investing structures & the buccal mucoperiostium of the maxillary premolar teeth & the MB root of the first molar in 28% of the cases. Branches of the Maxillary nerve Branches of the Infraorbital Nerve : 2. Anterior Superior Alveolar N It takes origin from the infraorbital n while passing in the infraorbital canal. It supplies the pulps, investing structures & the buccal mucoperiostium of the maxillary anterior teeth.  Branches of the Maxillary nerve Branches of the Infraorbital Nerve : 3. Terminal branches in the Face These are the end terminal branches of the infraorbital n after passing through the infraorbital foramen to the face. These are: a. Superior Labial for the skin & mucosa of the upper lip. b. Lateral nasal for the skin of the side of the Nose. c. Inferior Palpebral for the skin of the lower eyelid. Branches of the Maxillary nerve ◼ III. Posterior Superior Alveolar Nerve ◼ It takes origin from the Max. n in the infratemporal fossa then enters the posterior or infratemporal surface of the maxilla by passing through the Posterior superior alveolar foramen to supply the pulps, investing structures & buccal mucoperiostium of the maxillary molar teeth.  Superior Dental Plexus ◼ PSA Superior ◼ MSA dental plexus ◼ ASA  The Sphenopalatine Ganglion (Pterygopalatine Ganglion) ◼ It is the largest of the Parasympathetic ganglia in the Head (Sphenopalatine, Submandibular, Otic & Cilliary ganglia) ◼ Although it is anatomically suspended from the Maxillary nerve, it is Functionally related to the Facial nerve. ◼ Each parasympathetic ganglion has 3 roots ; sensory, sympathetic & parasympathetic roots.  Roots of the Sphenopalatine ganglion 1. Sensory root from the maxillary nerve. 2. Sympathetic root is the Deep Petrosal Nerve derived from the superior cervical sympathetic plexus around the Internal carotid artery while passing through the internal carotid canal. 3. Parasympathetic root is the Greater Superficial Petrosal Nerve branch of the Facial Nerve. ◼ The sensory & sympathetic roots pass through the ganglion without relay while only the parasympathetic root relays in the ganglion.  Roots of the Sphenopalatine ganglion ◼ In the foramen Lacerum, the Deep Petrosal & Greater superficial petrosal nerves join each other to form the Vidian Nerve (Nerve of Pterygoid canal) which reaches the sphenopalatine ganglion in the pterygopalatine fossa by passing through the pterygoid canal.  Branches of the Sphenopalatine Ganglion ◼ It should be kept in mind that each branch arising from the ganglion carries the 3 types of nerve fibers i.e sensory, sympathetic & parasympathetic fibers.  Branches of the Sphenopalatine Ganglion 1. Orbital branch sensory to the orbital periostium & carries parasympathetic secretomotor fibers conveyed through the zygomatic branch of the maxillary n to the Lacrimal nerve to supply secretomotor innervation to the Lacrimal gland. 2. Pharyngeal branch to mucous membrane of the Nasopharynx.  Branches of the Sphenopalatine Ganglion 3. Greater Palatine Nerve which passes through the greater palatine canal & comes out on the hard palate through the greater palatine foramen to supply the palatal mucoperiostium of the maxillary premolar & molar teeth. 4. Lesser Palatine Nerves (2or3 nerves) which pass through the greater palatine canal & comes out on the hard palate opposite wisdom tooth to supply the mucosa of the soft palate & the palatine tonsils.  Branches of the Sphenopalatine Ganglion 5. Long Sphenopalatine Nerve (Nasopalatine) It reaches the nasal cavity by passing through the sphenopalatine foramen to supply the mucous membrane of the nasal septum then descends & passes through the nasopalatine canal & foramen to reach & supply the palatal mucoperiostium of the upper anterior teeth(3-3). 6. Short Sphenopalatine Nerve It reaches the nasal cavity by passing through the sphenopalatine foramen to supply the mucous membrane of the upper part of the lateral wall of the nose.  Innervation of Maxillary Teeth ◼ Upper Anteriors ( 1-2-3 ) ◼ Pulp, investing structures & buccal M.P ASA Nerve ◼ Palatal M.P Nasopalatine Nerve  Innervation of Maxillary Teeth ◼ Upper Premolars (4-5) ◼ Pulp, investing structures & buccal M.P MSA Nerve ◼ Palatal M.P Greaterpalatine Nerve  Innervation of Maxillary Teeth ◼ Upper Molars (6-7-8) ◼ Pulp, investing structures & buccal M.P PSA Nerve ◼ Palatal M.P Greater palatine Nerve The Mandibular Nerve V3  The Mandibular Nerve V3 ◼ Course : ◼ The Mandibular Nerve is the largest division of the Trigeminal nerve. ◼ It is a mixed nerve. It is formed of a large sensory root & a much smaller motor root. ◼ The two roots leave the cranial cavity (Middle cranial fossa) through foramen Ovale.  The Mandibular Nerve V3 ◼ Just below the foramen, the 2 roots unit to form the trunk of the mandibular nerve. ◼ The trunk is very short & immediately divides into anterior & posterior divisions. ◼ The anterior division is mainly motor but carries small sensory fibers. ◼ The posterior division is mainly sensory although carries small motor fibers.  Branches from the Trunk 1. Nervus Spinosus It re-enters the cranial cavity by passing through foramen Spinosum to supply sensory fibers to the meninges of the middle cranial fossa. 2. Nerve to Medial Pterygoid It is a motor nerve to the medial pterygoid muscle. In its way to the muscle, it passes through the otic ganglion without relay & divides into two branches which supply the Tensor Palati & Tensor Tympani muscles.  Branches from the Anterior Division 1. Nerve to Lateral Pterygoid 2. Masseteric Nerve 3. Deep Temporal Nerves (2or3) 4. Long Buccal Nerve It is the only sensory nerve of the anterior division. It supplies the skin & mucosa of the cheek & the buccal M.P of the mandibular molars (6,7,8)  Branches from the Posterior Division 1. Auriculotemporal Nerve ◼ It takes origin from the posterior division by 2 roots which embrace the middle meningeal artery & unite behind the artery to form the nerve. ◼ Then it runs posteriorly deep to the neck of the mandible to enter the substance of the parotid gland. The nerve then leaves the gland through its upper end to reach the scalp.  Branches from the Posterior Division ◼ It supplies sensory innervation to the auricle & external auditory meatus of the ear, the temporal area of the scalp, TMJ & sensory & parasympathetic secretomotor innervation to the parotid gland from the otic ganglion. ◼ Branches: a. Auricular branch b. Glandular branch c. External auditory branch d. Articular branch e. Temporal branch  Branches from the Posterior Division 2. Lingual Nerve ◼ It runs downwards & forwards in the pterygomandibular space anterior & medial to the IAN. ◼ It then runs in a close relation to the lower wisdom as it crosses just above the periosteum opp the apical third of the third molar root. ◼ It then runs medially towards the tongue & floor of the mouth where the submandibular ganglion is suspended to it.  Branches from the Posterior Division ◼ It is then related to the submandibular salivary gland duct as the nerve crosses & hooks around the duct from lateral to medial. ◼ The Lingual nerve receives the Chorda Tympani nerve branch of the facial nerve which supplies taste sensations as well as parasympathetic secretomotor innervation to the submandibular, sublingual salivary glands & the minor sal gls of the tongue & floor of the mouth.  Branches from the Posterior Division ◼ The Lingual nerve supplies : 1. General sensations (Pain, temp,pressure & touch) to the lingual M.P of all mandibular teeth from 1 – 8. 2. General sensations to the mucosa of the floor of the mouth. 3. General sensations to the anterior 2/3 of the tongue. 4. The Chorda Tympani carries taste sensations from the anterior 2/3 of the tongue. 5. Postganglionic parasympathetic secretomotor innervation to the submandibular, sublingual & minor salivary glands.  Branches from the Posterior Division 3. Inferior Alveolar Nerve ◼ It passes downwards & forwards in the pterygomandibular space posterior & lateral to the lingual nerve. ◼ It then enters the IAC by passing through the mandibular foramen (IAF) on the medial surface of the ramus of the mandible.  Branches from the Posterior Division ◼ In the IAC, the IAN supplies the pulps & the investing structures of the mandibular molars. ◼ At the mental foramen between the first & second PM, it divides into Mental & Incisive nerves.  Branches from the Posterior Division ◼ The Mental nerve comes out of the mental foramen & passes into the substance of the lower lip & chin. The Mental nerve supplies: a. Buccal MP of the PM & anterior teeth. b. Skin & mucosa of the lower lip. c. Skin of the chin. ◼ The incisive nerve continues in the incisive canal to the midline. It supplies the pulps & investing structures of the lower anterior teeth.  Branches from the Posterior Division 4. Nerve to Mylohyoid ◼ This is the motor nerve of the posterior division of the mandibular nerve. It takes origin from the IAN before it enters the mandibular foramen. ◼ It then runs in mylohyoid groove on the inner surface of the body of the mandible to supply motor fibers to the Mylohyoid & Anterior belly of Digastric muscles. ◼ Sometimes, it carries some sensory fibers from the IAN to supply accessory sensory innervation to the pulps of the lower molars specially the first molar. Innervation of Mandibular Teeth ◼ Lower Anteriors ( 1-2-3 ) ◼ Pulp, investing structures Incisive Nerve ◼ Buccal M.P Mental Nerve ◼ Lingual M.P Lingual Nerve Innervation of Mandibular Teeth ◼ Lower Premolars ( 4-5 ) ◼ Pulp, investing structures IAN ◼ Buccal M.P Mental Nerve ◼ Lingual M.P Lingual Nerve Innervation of Mandibular Teeth ◼ Lower Molars ( 6-7-8 ) ◼ Pulp, investing structures IAN ◼ Buccal M.P Long Buccal Nerve ◼ Lingual M.P Lingual Nerve ◼ Accessory Innervations: 1. Anterior teeth receive accessory sensory innervations to their labial M.P from fibers of the opposite mental n that cross the midline to supply the opp anteriors. 2. Premolars receive accessory sensory innervation to their buccal M.P from the Cutaneous Coli n which is derived from cervical nerves C2 & C3. 3. Molars receive accessory sensory innervation to their pulps from nerve to mylohyoid which is a motor n but can carry some sensory fibers to the pulps of lower molars.  Submandibular Ganglion ◼ This Parasympathetic ganglion lies on the lateral surface of the Hyoglossus muscle between the lingual nerve above & the deep part of the submandibular salivary gland below. ◼ It is suspended to the lingual nerve by 2 nerve filaments. Although the ganglion is anatomically connected to the lingual nerve, it is functionally related to the Chorda Tympani branch of the Facial nerve.  Submandibular Ganglion ◼ Roots: 1. Sensory : From the Lingual nerve. 2. Sympathetic : From the SCS plexus around the Facial or Lingual artery. 3. Parasympathetic : From the Chorda Tympani branch of the Facial nerve. (Taste & Secretomotor)  Submandibular Ganglion ◼ Branches: 1. The ganglion gives direct postganglionic parasympathetic secretomotor fibers to the submandibular gland. 2. The ganglion gives postganglionic parasympathetic secretomotor fibers to the sublingual gland that join the lingual nerve for a short distance to reach the gland. 3. Fibers of the sensory root pass without relay in the ganglion & carry general sensations to the submandibular & sublingual salivary glands. 4. Fibers of the sympathetic root pass without relay in the ganglion & are vasomotor to the blood vessels of both glands. Anatomical Considerations Any QUESTIONS? Don’t ask me about the book Thank You !!