Local Anesthesia and Extractions for Dental Students: Simple Notes and Guidelines E-Book
Wamiq Fareed
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- Herausgeber: Bentham Science Publishers
- Kategorie: Fachliteratur
- Sprache: Englisch
This textbook presents basic principles of local anesthesia and exodontia for undergraduate dental program students and dental surgeons in training. Readers will understand key concepts and points that prepare them for daily oral and maxillofacial surgery
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Local Anesthesia and
Extractions for Dental Students:
Simple Notes and Guidelines
Editor
BENTHAM SCIENCE PUBLISHERS LTD.
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FOREWORD
I am pleased to write this foreword of this new book on local anesthesia and exodontia.
The Oral and Maxillofacial Surgery has an extensive body of literature; the dental extraction is one of the essential dentoalveolar procedures and the dentist should be well oriented to it scientifically and technically.
I found this book an excellent and impressive work which has been written in a concise and precise manner. The concept of local dental anesthesia and dental extraction is focused in book.
On reading this book, I have felt, it is not only recommended for undergraduates. It is also highly suitable for postgraduate trainees in their residency program, such as those in the level of Saudi Board of Oral and Maxillofacial Surgery program. It may help in a rapid revision of the management of simple and complicated dental extraction during the pre-exam period.
I dedicate this book to undergraduates and postgraduates trainees with the hope that it fulfills their need in understanding the concepts of dental extraction.
PREFACE
The target of this book is the undergraduate dental students to give them the basic concept and outline of the principle of local anesthesia and exodontia in brief short notes form that is easy to understand, remember and to implement clinically.
The local anesthesia and exodontia is the fundamental part of Oral Surgey that should be known well by all dentists, since it is one of the daily surgical procedures in dentistry.
This book is suitable as well for the oral & maxillofacial surgery trainees who are looking for a concise rapid revision of management of simple, complex dental extraction and management of medically compromised patients.
I dedicate this book to my students everywhere, my parent and family. I would like to express sincere thanks to my wife for continuous support, encouraging and help.
Acknowledgments
I would like to acknowledge Dr. Fadi Jarab and Dr. Wamig Fareed for their contribution in this work (Chapter 3 and part 2 in chapter 4 written by Fad Jarab and Chapter 6 by Wamiq Fareed).
The figures of this book has been drawn by: Dr. Omar Mohammad Dad. I would like to acknowledge him for his help in producing the figures of this book, his help was valuable and appreciated.
This book has been revised by: Dr. Ghaith Gazal, and Dr. Albaraa B. Alolayan. I would like to acknowledge them for their contribution in this work.
With appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using some of their illustration in chapter one (The Outline of the Trigeminal Nerve Anatomy).
Conflict on Interest
The authors confirm that this article content has no conflict of interest.
Part I: The local Anesthesia in Dentistry
The Outline of the Trigeminal Nerve Anatomy
Esam Ahmad Z OmarFadi JarabWamiq Musheer FareedAbstract
The primary sensory nerve of the Oro-facial area is the trigeminal nerve. Understanding the anatomy of this nerve is essential for the dental practitioner to understand the pain mechanism and dental pain pathway. Most of the anatomy books discuss the details of the anatomical relation of Trigeminal nerve instead of an understanding of neural fibers carry by the nerve. This chapter discusses the anatomy, the neural fibers of each branch and the neural connection (nuclei) of the nerve.
The Trigeminal nerve is mixed Cranial nerve comprises principally of neurons for sensation. It enters the trigeminal ganglion after travelling parallel to the pons surface and exiting the brain. The trigeminal ganglion makes up the spinal nerve by acting as the dorsal root ganglion.
The trigeminal ganglion divides into three major branches, innervating different bone, teeth and facial dermatome. Every branch follows a different path and site to exit the cranium.
The Opthalmic nerve, the primary V1 branch, exits via the superior orbital fissure of the cranium, reaching the orbit to innervate the skin existing above the forehead and eye as well as the globe of the eye.
The Maxillary nerve makes the second V2 division, leaving via the foramen rotundum, into the pterygopalatine fossa, an area located posterior to the orbit. Thereafter, it again enters the inferior orbital fissure, making its way to the infraorbital foramen on the face, innervating the skin of the nose and cheek and below the eye.
The Mandibular nerve, the V3 third division, also has a motor component leave with the nerve and joining it at the foramen ovale (the motor root).
The different trigeminal nerve nuclei: Fig. (1.1)
The sensory nucleus is primarily for touch and temperature, present in the pons.The spinal nucleus is responsible primarily for temperature and pain, and is a sensory nucleus.The sensory nucleus is ventromedial to motor nucleus.The mesencephalic nucleus is the proprioceptive nucleus for all muscles of mastication.
Fig. (1.1)) Trigeminal nerve nuclei (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).Nerves supplying parasympathetic fibers in head and neck area:
Glossopharyngeal nerve (otic ganglion)Facial nerve (pterygopalatine ganglion, submandibular ganglion)Oculomotor nerve (ciliary ganglion)The trigeminal nerve receives the parasympathetic and the special sensation (taste) from the following:
The nervus intermedius, or "nerve of Wrisberg" is the intermediate nerve of the facial nerve (cranial nerve VII) situated among the vestibulocochlear nerve (cranial nerve VIII) and the motor of the facial nerve.
The nucleus of nervus intermedius:
Tractus solitaries (Taste nucleus): It contains the sensory taste (from tractus solitarius) which leaves the pons as nervus intermedius as a branch of facial. It gives branch to: Chorda tympani nerve travelling towards the submandibular ganglion.Greater petrosal nerve travelling towards the pterygopalatine ganglion.The superior salivary nucleus: parasympathetic secretory-motor fibers to: Submandibular, sublingual salivary gland to sublingual ganglion through the chorda tympaniAnd to the minor salivary nucleus of nose and palate through the greater petrosal nerve which joins --- the ptrygo-palatine ganglion. It is made of parasympathetic fibers coming from the superior salivary nucleus and the tractus solitarius’ sensory taste and exiting alongside the facial nerve in the facial canal, joining it’s motor root at the geniculate ganglion. Parasympathetic axons originate from the superior salivatory nucleus. No synapse is present when these fibers pass the geniculate ganglion. Some of these preganglionic parasympathetic filaments, as they leave the geniculate ganglion, move within the greater petrosal nerve. This way they form a synapse with the pterygopalatine ganglion. These postganglionic neurons provide the lacrimal gland with parasympathetic innervation t through their axons.The function of the tractus solitarius (solitary tract):
Solitary tract are structures in the brainstem that receive and carry taste sensation from the visceral sensation from vagus, glossopharyngeal nerve (IX) and facial nerve through it,s fibres to trigeminal nerve (VII). Taste from the anterior part of the tongue, more specifically two third (2/3rd) area, through the facial nerve fibers given to the mandibular branch of the trigeminal nerve by chorda tympani The fibers of the facial nerve when leave the geniculate ganglion at the middle ear, they combine with the mandibular nerve at about one centimeter below the base of the skull by the chorda tympani. The posterior 1/3rd general and taste sensation through the glossopharyngeal nerve.Chemoreceptors in the carotid (by means of IX) and aortic body (through X).Stretch receptors from the aorta and carotid supply routes called blood vessel baroreceptors.Petrosal nerve (Fig. 1.2) (a nerve going through the temporal bone, specifically the petrous part):
Deep petrosal nerveLesser petrosal nerve (also called the lesser superficial petrosal nerve)Greater petrosal nerve (also called as the greater superficial petrosal nerve)External superficial petrosal nerveFig. (1.2)) Petrosal nerve (Acknowledgments: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).Deep Petrosal Nerve
Originating from the carotid plexus, the petrosus profundus or deep petrosal nerve travels within a canal positioned lateral to the internal carotid artery, known as the carotid canal.
It contains postganglionic sympathetic filaments supplied by the superior cervical ganglion.
As it passes through the cartilaginous substance of the foramen lacerum, it frames the nerve of the pterygoid canal (Vidian nerve) by combining with the greater petrosal nerve. At that point, without synapsing, it travels through the pterygopalatine ganglion and later joins the postganglionic parasympathetic filaments in supplying the lacrimal gland and nasal cavity.
The parasympathatic part of the large petrosal nerve, known as the greater superficial petrosal nerve rises from the geniculate ganglion of the facial nerve (it’s nucleus in tractus solitarius); travelling via the hiatus of the facial canal, entering the cranium, and continues underneath the dura mater present in the anterior temporal petrous bone’s groove. Afterwards it emerges into the foramen lacerum filling cartilaginous substance and forms the Vidian nerve, the nerve of the pterygoid channel, after attaching with the deep petrosal nerve (sympathetic part).
Nucleus of greater petrosal nerve (Fig. 1.3):
Nervus intermedius: leave the cranial cavity via the facial nerve Tast sensationSuperior salivary nucleus: leave the cranial cavity via facial nerve Salivation: for the minor the salivary glands at the nose, plate.Vidian Nerve
Vidian nerve consists of:
Deep petrosal nerve (sympathetic root)And greater petrosal nerve (parasympathetic root)The nerve present in the pterygoid canal is known as Vidian nerve. It comes to be after the combining of two nerves in the foramen lacerum the deep petrosal nerve, which forms the sympathetic root, and the greater petrosal nerve, which forms the parasympathetic root. These are united by a little rising otic ganglion branch called the sphenoidal branch. Finally, on reaching the pterygopalatine fossa, it combines with the pterygopalatine ganglion.
Fig. (1.3)) Nucleus of greater petrosal nerve (Acknowledgments: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).Lesser Petrosal Nerve (Fig. 1.4)
Nucleus of the lesser petrosal:
Nervus intermedius: leave the cranial cavity via the facial nerve Tast sensationInferior salivary nucleus: leave the cranial cavity via glossopharyngeal nerve (CN IX) via Jac1bson's nerve Salivation: for the parotid gland.The lesser petrosal nerve (Fig. 1.4) conveys parasympathetic (secretory) filaments from both the tympanic plexus (from glossopharyngeal nerve (CN IX) by means of Jacobson's nerve – through the facial nerve from the nervus intermedius and the inferior salivary nucleus and to the parotid gland by means of the otic ganglion. It starts at the geniculate ganglion, advancing through its own particular canal again into the middle cranial fossa, between the two dura mater layers, joining the otic ganglion by leaving the skull through foramen ovale.
Fig. (1.4)) Lesser petrosal nerve (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).The external superficial petrosal nerve is a sympathetic branch, a part of the middle meningeal artery.
Chorda Tympani Nerve
Chorda tympani nerve contains filaments from two two brain stem nuclei.
Superior salivatory nucleiThe nucleus of tractus solitarius: Are taste neurons responsible for a taste sensation. Subsequent to synapsing in this nucleus auxiliary axons ascend in the lateral lemniscus to relay in the thalamus. This pathway then goes to the essential gustatory cortex through the posterior limb of internal capsule.A sensory branch of facial nerve (Nervus intermedius of Wrisberg) joins the facial nerve here. It passes on individual sensory filaments from taste buds present in the anterior 2/3 of the tongue and delicate sense of taste. It additionally contains secretomotor filaments to salivary tissues present the floor of the mouth. Nerves intermedius exits the mind stem disciple to the vestibulocochlear nerve. At the level of inside sound-related meatus, it leaves this nerve, converging with the facial nerve.
Chorda tympani nerve (Fig. 1.5): exits the facial nerve before it leaves the stylomastoid foramen. It is the facial nerve’s biggest branch in its intrabody compartment (intrapetrous - inside the temporal bone’s petrous part). It emerges beneath the nerve to stapedius. It navigates anterosuperiorly through the posterior canaliculus typically combined with a posterior tympanic branch of the stylomastoid artery.
Fig. (1.5)) Chorda tympani nerve (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).Chorda Tympani Nerve Function
It causes the sensation of taste from the anterior part of the tongue, specifically two third (2/3) areaSupplies secretomotor to the salivary organs (minor and major salivary glands) present in the mouth’s floorConveys sensation (general sensation) from the anterior 2/3 area of tongue which includes pain and temperatureSupplies secretomotor fibers to the submandibular and sublingual salivary glandsSupplies the tongue with efferent vasodilator fibers.The Ophthalmic nerve is primarily a sensory nerve (Fig. 1.6). It is responsible for supplying:
The corneaIrisCiliary bodyConjunctivaThe lacrimal glandThe nasal cavity mucous membraneThe skin over eyelids, eyebrow,The skin over Forehead,And The skin over the noseFig. (1.6)) The Ophthalmic nerve is primarily a sensory nerve (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).It is the smallest trigeminal nerve branch, emerging from the ganglion’s upper part known as the semilunar ganglion. It is a 2.5 cm long leveled band, travelling beneath the oculomotor and trochlear nerves, along the cavernous’ lateral wall. Thereafter it enters the superior orbital fissure making its way to the orbit
- It produces three divisions:
Nasociliary,Frontal,and Lacrimal.The ophthalmic nerve combines with sympathetic filaments of the cavernous that communicate with the abducent, oculomotor, and trochlear nerves.
The smallest branch of the ophthalmic nerve is the lacrimal nerve. In some cases this nerve gets a fiber from the trochlear nerve, however mostly it is obtained from the branch running through the ophthalmic to the trochlear nerve. It forwards towards a separate dura mater tube, entering the orbit through the Rectus lateralis. When here it travels besides the upper surface of the Rectus lateralis, along the lacrimal artery course, and afterwards joins the maxillary nerve’s zygomatic branch.
Thereby, it reaches the lacrimal glands and emits a few fibers, which are responsible in supplying the organ and the conjunctiva.
At last, it punctures the orbital septum, and joins with the facial nerve fibers and supplies the skin of the upper eyelid.
Occasionally, the zygomaticotemporal branch from maxillary takes the place of the lacrimal nerve when it is missing. At instances when only the last branch is missing, it is substituted by a continuation of the lacrimal.
The Frontal Nerve
This reaches the orbital cavity via the superior orbital fissure (largest branch of the ophthalmic) and keeps running between the Levator palpebrae superiors and the periosteum. As it reached halfway through the base and apex of the orbit it differentiates into, supratrochlear and supraorbital branches.
The smaller branch is the supratrochlear nerve (n. supratrochlear), which goes over the superior oblique muscle. This branch produces descending fibers which connect with the nasociliary nerve’s infratrochlear branch of. Thereafter it leaves the orbit through the supraorbital foramen, on the forehead, it ascends beneath the corrugator and frontalis, and pierce these muscles after dividing into branches; it supplies the conjunctiva, upper eyelid skin and the forehead skin near the middle line.
The upper eyelid is supplied by palpebral fibers by the supraorbital nerve (n. supraorbital) which moves between the supraorbital foramen. It then travels to the temple, ending in two divisions, a lateral and medial, supplying the scalp, going till the lambdoidal suture. Initially they are present underneath the Frontalis, with the medial branch passing through the muscle, and the lateral branch through the galea aponeurotica. The pericranium is supplied by little twigs of both branches.
The orbital cavity also has the Nasociliary Nerve (n. nasociliaris; nasal nerve), entering between the lateral rectus muscle’s two heads and positioned among the inferior and superior rami of the third cranial nerve. Crossing the optic nerve, it slants underneath the Obliquus and Rectus superior, present at the orbital cavity’s medial wall. Thereafter it reaches the anterior ethmoidal foramen, and, travelling to the skull, crosses the lateral edge of the frontal surface of cribriform plate at a groove and the bone of ethmoid. Following its path, it passes through an opening along the edge of the crista galli, finally entering the nasal cavity. It then divides into nasal branches supplying the front part of the septum and mucous membrane of the lateral wall. At the end it forms the external nasal branch, between the lateral nasal cartilage and the lower border of the nasal bone, travelling underneath the Nasalis muscle, thereby supplying the peak of the nose and skin of the ala.
The nasociliary nerve differentiates into accompanying branches, vascularization: the lengthy foundation of the ethmoidal nerves, the ciliary ganglion and the long ciliary.
The radix longa gangili ciliaris which is the long base of the ciliary ganglion originates between the two Rectus lateralis from the nasociliary. It progresses on the optic nerve’s lateral side, reaching the postero-superior point of the ciliary ganglion. Occasionally a fiber joins it from the prevalent trochlear nerve ramus or the cavernous plexus of the sympathetic.
The ciliares longi or more commonly called the long ciliary nerves are less in number and begin at the nasociliary, which passes the optic nerve. Travelling alongside the ciliary nerves, short in size, of the ciliary ganglion, they enter the posterior of the sclera, passing through it and the choroid, reach the cornea and iris. These long ciliary nerves also possess sympathetic fibers connecting the superior cervical ganglion with the Dilator pupilae muscle.
Before the nasociliary enters the anterior ethmoidal foramen, it gives rise to the infratrochlear nerve (infratrochlearis). It travels along the Rectus medialis upper surface and is united with a fiber from the supratrochlear nerve when close to the pulley of the Obliquus superior. It then reaches the medial angle of the eye, to supply the eyelids skin, lacrimal sac, conjunctiva, caruncula lacrimalis and nose’s side.
The ethmoidal cells are provided by the ethmoidal branches. The branch present posteriorly supplies a few fibers to the sphenoidal sinus and exits the orbital cavity via the posterior ethmoidal foramen.
The Ciliary Ganglion (Fig. 1.7), known as the lenticular or ophthalmic ganglion. The ciliary is basically a sympathetic ganglion that is small, of gray-reddish and pin sized. It is present within adipose tissues lying among the Rectus lateralis muscle and optic nerve, arranged at the back of the orbit. It generally lies on the ophthalmic artery’s lateral surface. It has three roots which reach its posterior surface. The nasociliary gives rise to the sensory root. The parasympathetic motor is connected with the nucleus of oculomotor in the brainstem, the Presynaptic parasympathetic fibers derive from the Edinger-Westphal nucleus. Axons from the nucleus of Edinger-Westphal and the nucleus of oculomotor run together in the brainstem and form the oculomotor nerve. Thereafter the motor root reaches the Obliquus inferior after it originates from the branch of the oculomotor nerve. The motor root contains efferent strands of sympathetic nature (preganglionic filaments) emerging from the nucleus of the oculomotor nerve in the brain (mid-brain) to the ciliary ganglion where a synapse is formed with filaments of neurons.
Fig. (1.7)) The Ciliary Ganglion (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).The postganglionic travels to the:
Sphincter muscle of the pupilAnd Ciliary muscle.The cavernous plexus of the sympathetic gives rise to the sympathetic root which is mostly joined with the long root.
The short ciliary nerves form its branches, which are sensitive in nature and originate from the forepart of the ganglion. They are around six to ten, divided in two groups depending upon their superior and inferior angles. The larger is the lower bundle. They travel ahead with the ciliary arteries in a wave-like course, one present above the optic nerve while the other underneath it. They are also united with the nasociliary long ciliary nerves. They reach the back of the eye glob and enter the sclera, forwarding in delicate depressions on the internal surface. These are further divided into the:
Iris,Ciliary muscle,And Cornea.Maxillary Nerve
Second division of the trigeminal nerve. The maxillary nerve (Fig. 1.8) emerges from the middle part of the trigeminal ganglion, moves along the sphenoid bone, passing the Lateral wall of the cavernous sinus, and leaves the cranium to the upper part of the pterygopalatine fossa. It then curves laterally at the infratemporal fossa through the pterygomaxillary fissure. It descends the fossa, moving forward into the infraorbital nerve through inferior orbital fissure.The Maxillary nerve branches in the ptrygo-palatine fossa.Near its origin gives meningeal branches.Two ganglionic branches arise in the pterygopalatine fossa which join the sphenopalatine ganglion.Gives off the posterior superior alveolar nerve and the zygomatic nerve while the maxillary nerve is present in the infratemporal fossa.The maxillary nerve continues as the infra-orbital nerve.The infra-orbital nerve is the maxillary nerve’s continuation as it reaches the inferior orbital fissure. It proceeds to the roof of maxillary antrum which is the floor of the orbit. It passes first at the infraorbital groove, and is present alongside the infra-orbital branch of the maxillary artery as well as its fellow vein. Then it reaches the infra-orbital canal and finally emerges below the infraorbital rim, through the infra-orbital foramen, into the face. Here it is under cover of the levator labii superiors and orbicularis oculi, and divided into the palpebral, nasal and labial branches.
Fig. (1.8)) The pterygopalatine ganglion (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).The Pterygopalatine Ganglion (Fig. 1.8) (nasal ganglion, sphenopalatine ganglion)
The head and heck contain four parasympathetic ganglia:
The pterygopalatine ganglion,The submandibular ganglion,The otic ganglion,and Ciliary ganglion.The pterygopalatine is found in sphenopalatine fossa near the sphenopalatine foramen. It is a parasympathetic ganglion. It is heart-shaped, gray to reddish in color, and crosses the pterygopalatine with the maxillary nerve.
The sphenopalatine ganglion (pterygopalatine ganglion) supplies:
The Paranasal sinuses,The lacrimal gland,The nasal cavity and nasopharynx mucosa and it,s minor salivary glands,The gingiva of the maxilla,The hard palate mucous membrane and minor salivary glands,It continues anteriorly as nasopalatine nerve,Branches of Maxillary nerve.According to origin it may divide into four branches:
In the pterygopalatine fossaOn the faceIn the infraorbital canaland In the cranium.In the pterygopalatine fossa: Sphenopalatine.Zygomatic.Posterior superior alveolar.In the Infraorbital Canal: Anterior superior alveolar.Middle superior alveolar in 28% of cadavers.On the Face: External nasal.Inferior palpebral.Superior labial.In the cranium: Middle meningeal. The middle meningeal nerve: after it originates from the semilunar ganglion, it originates from the maxillary nerve; it is running with the middle meningeal artery and provides for the dura mater. The Zygomatic nerve: emerges from the pterygopalatine fossa’s maxillary nerve and reaches the orbital cavity via the inferior orbital fissure, and distributes into the following:Zygomaticofacialand Zygomaticotemporal. The zygomaticotemporal branch: is divided around the skin present at the side of the forehead. The zygomaticofacial branch: reaches the face via the zygomatic bone foramen. It gives supply to the skin of the cheek by perforating the orbicularis oculi.The pterygopalatine Branches (Sphenopalatine): two branches exist which reach the pterygopalatine (sphenopalatine) ganglion (sensory roots).The superior posterior alveolar : passes in the infraorbital groove before it arises from the maxillary nerve. Usually two exist in number. They enter the mucosa and send branches to the maxillary sinus mucosa, gums, adjacent parts of the mucous layer of the cheek and all molar teeth except the first molar’s mesiobuccal root.The middle superior alveolar nerve (only has been reported in 28% of cadavers): emerges from the infraorbital canal, and provides supply to two premolar teeth after passing through the maxillary antrum’s lateral wall.The anterior superior alveolar branch: originates just before the nerve exits the infraorbital foramen; it slips in a channel in the maxillary sinus’ front wall and branches to supply the canines and incisors and the 1st and 2nd premolar in 72% of cadavers.The Inferior orbital nerve as it emerges from the face’s infraorbital foramen:
Inferior palpebralThe Superior LabialThe External NasalThe Pterygopalatine Ganglion (Fig. 1.9)
Roots:
The nervus intermedius which is a part of the facial nerve gives rise to its parasympathetic root via the greater petrosal nerve (it’s nuclei are: Tractus Solitarus for taste sensation and Superior Salivary Nucleus as secretory motor). Afterwards it forms the vidian nerve by joining the sympathetic root which is the deep petrosal nerve. The vedian nerve is a combination of the deep petrosal nerve (sympathetic) and the greater petrosal nerve (parasympathetic).
Sensory root is originated as two sensory branches from the maxillary nerve. The sensory root carries some of the taste fibers from the nervus intermedius to the palates both hard and soft.
Branches of the pterygopalatine ganglion:
Lesser palatine nerveGreater palatine nervePosterior superior lateral nasal branchNasopalatine nervePharyngeal branch of the maxillary nerveFig. (1.9)) The pterygopalatine ganglion (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).Regional anatomy of maxillary nerve:
Lateral nasal wall supplied with: Posterior superior lateral nasal nerve – maxillary nerveGreater palatine nerve – maxillary nerveNasopalatine nerve – maxillary nerveAnterior ethmoidal nerveHard palate Greater palatine nerveSoft palate Lesser palatine nerveAnterior maxillary teeth Anterior superior alveolar nerveMaxillary premolars teeth Middle superior alveolar nervePosterior teeth except for the mesiobuccal root of 1st molar Posterior superior alveolar nerveThe mandibular nerve (inferior maxillary nerve): provides for the:
The skin of the temporal and auricular areas,Gums and teeth of the mandible,The lower part of the face,The lower lip,The anterior mucosa two-thirds of the tongue,The muscles of mastication.Of the three trigeminal divisions, it is the largest. It consists of two roots:
Large sensory root emerges from the lower surface of the trigeminal ganglion,Small motor root emerges from the motor nucleus of the trigeminal. It travels underneath the ganglion, joining the sensory root, just after few millimetres from the exit (the foramen ovale) below the skull base (Fig. 1.10).Fig. (1.10)) The mandibular nerve (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).Branches: At nerve is further divided at the base of the skull, giving off:
Nervus spinosus (Recurrent branch)The nerve to the medial pterygoid,And after that branched into anterior and posterior trunks. Nervus spinosus (Recurrent branch): enter the cranium via the foramen oval to the foramen spinosum beside the middle meningeal artery. It moves along the main meningeal artery divisions and the dura mater is supplied. It forms posterior and anterior branches which the posterior branch supplies as well the mastoid cells mucous lining.The medial pterygoid Nerve (pterygoideus internus).The deep muscle surface is invaded by the nerve to the medial pterygoid muscle. In addition it also sends one or two filaments towards the otic ganglion.
Then the mandibular nerve branches into:
Anterior division andPosterior divisionThe Anterior Division
This division receives almost all of the trigeminal motor root fibers and is the smaller of the two divisions of the mandibular nerve. It further supplies:
The masticatory muscles (muscles of mastication)The mucous membrane and skin of the cheek.It is divided into:
Nerve of lateral pterygoid muscle (motor)The masseteric (motor),Deep temporal (motor),Long buccal nerve (sensory).The Masseteric Nerve passes the mandibular notch along with the masseteric artery, reaching the Masseter’s deep surface; it gives fibers to the temporomandibular joint.
The Deep Temporal Nerves enter the Temporalis’ deep surface after turning upward over the lateral pterygoid muscle’s upper head.
The long buccal nerve goes through the pterygoid muscle, between its two heads. It descends underneath or through the lower part of the Temporalis; branches on the surface of the Buccinator after rising from under the anterior surface of the Masseter. The buccal nerve supplies the buccal mucous membrane lining of the mouth and the skin over the Buccinator muscle.
The nerve of lateral pterygoid muscle: This nerve frequently arises in conjunction with the long buccal nerve.
The Posterior Division
The larger division on the mandibular nerve is the posterior division. It is basically sensory, yet gets a couple of the motor root fibers. It branches into:
Lingual,Auriculotemporal,Inferior alveolar nerves.The Auriculotemporalis, commonly known as Auriculotemporal Nerve, originates from two roots, present among the middle meningeal course and rises to the foramin oval. It reaches the neck’s medial side of the mandible after running in reverse underneath the lateral pterygoid muscle. Afterwards, it rotates upward along with the superficial temporal artery, located between the mandibular condyle and mandibular auricula, beneath the front of the parotid gland. Passing this gland, it rises above the zygomatic arch, and terminates with superficial temporal branches.
The otic ganglion (Fig. 1.11) is a small parasympathetic ganglion located in the infratemporal fossa medially to the surface of the mandibular nerve and below the foramen ovale.
Fig. (1.11)) The otic ganglion (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).It receives the fibers that are pre-ganglionic of the glossopharyngeal nerve and innervates the parotid gland for salivation.The parasympathetic pre-ganglionic nucleus of the otic ganglion located at the inferior salivary nucleus.
Pre-ganglionic fibers leave the glossopharyngeal nerve with the tympanic branch and then the lesser petrosal and the tympanic plexus nerve pass to join the otic ganglion, the fibers synapse, and the postganglionic fibers are given to joining auriculotemporal nerve, which supplies the parotid gland. They produce vasodilator and secretomotor effects.
It divides into the following branches:
Temporal regionParotidThe external acoustic meatusAnterior auricular.The Lingual Nerve, known as the lingualis, reaches:
The mucosa of the anterior two-third areas of the tongue. It passes initially below the lateral pterygoid muscle in the front and medial to the inferior alveolar nerve, it forms an acute angle to join the chorda tympani. The nerve then travels among the ramus of the mandible and medial pterygoid muscle, crossing obliquely over the superior Constrictor muscle present at the tongue’s side and the styloglossus. Moving ahead it moves between the areas between the submandibular glands’s deep part and the Hyoglossus, finally reaching through the submandibular gland duct, towards the tongue’s tip, present beneath the mucous membrane.Its branches reach to provide supply to:
The submandibular gland,The sublingual gland,The gums,The mucous membrane of the mouth,And the anterior two-thirds tongue’s mucous membrane.The largest division of the posterior part of mandibular nerve is the inferior alveolar nerve. It moves down towards the inferior alveolar artery, initially underneath the lateral pterygoid muscle, and later within the sphenomandibular ligament and the mandibular ramus, reaching the mandibular foramen. Thereafter it moves to the mandibular canal, positioned under the teeth, towards the mental foramen, separating into two terminal divisions, mental and incisive.
Mylohyoid nerve emerges from the inferior alveolar as it reaches the mandibular foramen. It innervates the Digastric muscle’s anterior belly and mylohyoid after passing through the medial surface of the ramus of the mandible, and entering the lower surface of the mylohyoid.
The dental branches known as the inferior alveolar nerve provide for the molar and premolar teeth. The incisive branch of the inferior alveolar nerve supplies the incisor teeth and canine.
The mental nerve leaves the mandibular canal through the mental foramen which located in most instances between the 1st and 2nd premolars, and supply:
The lower lip’s mucous membrane and skin,The skin of the chin.Fig. (1.12)) Submandibular Ganglion (Acknowledgment: with appreciation and thanks to Instant Anatomy. 10 Summerfield Cambridge, CB3 9HE, UK. http://www.instantanatomy.net, for their permission for using this illustration).Submandibular Ganglion (Fig. 1.12): The submandibular ganglion is fusiform and small in size. It is located on the submandibular gland’s medial surface, the hyoglossus, present close to the mylohyoid’s posterior border. The anterior and posterior parts of the ganglion are connected with two fibers to the lingual nerve. At the posterior end, it joins the chorda tympani nerve’s branch, passing through the lingual sheath. Such are the preganglionic efferent sympathetic filaments of the facial nerve and the superior salivatory nucleus.
Roots of submandibular ganglion:
Nervus intermedius: leave the cranial cavity via the facial nerve Taste sensationSuperior salivary nucleus: leave the cranial cavity via facial nerveSalivation: for the minor the salivary glands at the nose, plateIts branches supply:
The mucous membrane of the mouthThe sublingual gland,Submandibular glandThe anterior two-thirds tongue’s mucous membrane,And the gums.Summary for sensory dental innervations (Fig. 1.13):
Fig. (1.13)) Summary for sensory dental innervations. The middle superior alveolar nerve is present in 28% of anatomically dissected cadavers, in the remaining 72% this nerve can not be recognized and the premolars are mostly supplied by posterior superior alveolar nerve.Bibliography
[1]Sinnatamby CS, Last RJ. Last’s anatomy: regional and applied 2006.[2]Gray H, Clemente CD. Anatomy of the human body 1985.[3]Instant AnatomyLearn human anatomy online Available at: https://www.instantanatomy.co.uk/Physiology of Pain
Esam Ahmad Z OmarFadi JarabWamiq Musheer FareedAbstract
In this chapter, the mechanism of pain, pain pathway from Oro-facial area and the physiological principle of pain have been discussed in detail. In order to understand the mode of action of local anesthesia, it is essential to understand the pain physiology. This chapter contains the essential details of pain physiology that may be needed for an understanding of the mechanism of local anesthesia. The endogenous analgesic system is an important modulator part for pain intensity and a major contributor to pain gate theory, all that has been discussed in a concise and precise way to give the complex information in a simple way to understand and remember.
Part 1 - Action Potential
Action Potential
An impulse of electrical nature comprising of self-spreading series of depolarization and repolarization, transmitted over the plasma membrane of neurons, as the nerve impulse is transmitted passes over the plasma membrane of the neural and muscular cells when it is contracting.
The Resting Membrane Potential
When the neuron is not actively sending signals, it is referred as being at a state of 'Rest Membrane Potential.' The cell membrane of neurons possesses a pump of protein nature that is known as the sodium-potassium pump (Na+ K+ ATPase). The cell membrane at rest utilizes active transport by using ATP energy to pump three sodium ions out of the neuron (3 Na+) and two potassium ions (2 K+) into the cell (Table 2.1 shows the concentration of different essential ions around the cell membrane of the neuron).
Graded Potentials
Graded potentials (or receptor potentials) are temporary hyperpolarization or depolarization within a specific area of the plasma membrane that is able to produce changes causing local flow of current in response to stimuli that reduces separation.
The receptor potential’s magnitude is an indication of and directly related to the intensity of the stimulus. When the strength of the stimulus is high, it causes greater molecule channels to open and thereby a greater voltage change, whether it is depolarization or hyperpolarization. As a result, the current travels farther (Table 2.2).
Definitions
Threshold is the amount of stimulus at the level of the receptors (Graded potentials or receptor potentials) needed to start the action potential.
If the stimulus strength is high enough to cause depolarization crossing a basic critical level then the layer keeps on depolarizing alone, and does not depend on the stimulus. The threshold edge is roughly 20mV less negative as compared to the resting membrane potential. When threshold edge is achieved (-55mV), depolarization occurs automatically.
Depolarization takes place as the membrane potential reaches a less negative figure (the threshold point), shifting towards zero, making the neuron more excitable. It occurs through the activation of the voltage-gated Na+ channels, allowing the influx of Na+ ions into the neuron.
Repolarization is the point at which a cell layer's charge comes back to negative after depolarization. This occurs when the Na+ channel gates become inactive and closed. At the same time, the K+ channel gates become active and open, causing movement of K+ outside the neuron.
Hyperpolarization happens when the layering potential turns out to be more negative, moving far from zero, and below the rest membrane potential.
After-hyperpolarization occurs by increasing Potassium (K+) ion permeability. The neuron’s membrane potential is far from the point of threshold causing the cell to undergo a relative refractory period (RRP). The neuron needs an extraordinary stimulus to create an activity (action potential). These activities (depolarization and hyperpolarization signs) are transient. The neuron’s membrane potential returns back to its resting state, once the stimulus is removed.
Action Potentials
Electrical signals travelling long distances are called action potentials (Fig. 2.1). These signs move along the entire neuronal membrane. In graded potentials the greatness of the sign disseminates, however, the size of the activity potential is kept up all through the length of the axon. Furthermore, action potentials are not stimulus dependent as the graded potentials. The magnitude of action potentials always remains constant.
Action potentials of similar magnitudes exist. A supra-threshold activator (stimuli), one that is bigger than the expected value and requires depolarizing the plasma membrane essentially to threshold, does not form greater action potentials, rather, it increases recurrence (frequency) of action potential production and generation.
Fig. (2.1)) Steps of action potential.
