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Central neural pathways relevant to the trigeminal system: midbrain V nucleii functions and their related other cranial nerve nucleii. VPM - ventral posteromedial nucleus in the thalamus which
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In order to understand the underlying principles of orofacial pain it is important to understand the corresponding anatomy and mechanisms. Paper 1 of this series explains the central nervous and peripheral nervous systems relating to pain. The trigeminal nerve is the ‘great protector’ of the most important region of our body. It is the largest sens...
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... the Italian anatomist and physician 50% of the sensory cerebral cortex area Fallopius (1523–1562) discovered that is dedicated to the processing of orofacial these branches merged as one, that the sensation ( Figure 1), and therefore the 5th cranial nerve was created. In 1732, impact of trigeminal nerve injury may be the Danish anatomist Jacques-Bénigne significantly larger than in other areas of Winslow (1669–1760) ascribed the name the body. 2 ‘nerf trijumeau, referring to the three Damage to this sensory nerve can peripheral branches of this nerve, and the result in numbness (anaesthesia), tingling name ‘trigeminal nerve’ was born meaning altered sensation (paraesthesia), pain or ‘three twins. The trigeminal nerve is the a combination of the three in 50–70% of largest of the cranial nerves and the largest cases. 3 sensory nerve. It is a mixed sensory nerve Pain is common in sensory nerve injuries made up of both sensory and motor axons, and, due to the orofacial region being and it plays a particularly important role in affected, results in significant functional sensations of the face and head regions. problems including: eating, speaking, The unique nature of the kissing, drinking, applying make-up and trigeminal nerve is related to several shaving, in fact just about every social factors: function that we take for granted. 4 The head facial area is made up of The resultant psychological disability a variety of unique tissues such as the of chronic altered sensation or pain meninges, cornea, nasal sinuses, oral includes changes in self-perception, mucosa and tooth pulp, that require reduced quality of life, social disabilities specialized sensory innervations. 2 and handicap. Many patients often There is constant neural activity input find it hard to cope with pain in the related to orofacial function. trigeminal system. 5 April 2015 50% of the sensory cerebral cortex area is dedicated to the processing of orofacial sensation (Figure 1), and therefore the impact of trigeminal nerve injury may be significantly larger than in other areas of the body. 2 Damage to this sensory nerve can result in numbness (anaesthesia), tingling altered sensation (paraesthesia), pain or a combination of the three in 50–70% of cases. 3 Pain is common in sensory nerve injuries and, due to the orofacial region being affected, results in significant functional problems including: eating, speaking, kissing, drinking, applying make-up and shaving, in fact just about every social function that we take for granted. 4 The resultant psychological disability of chronic altered sensation or pain includes changes in self-perception, reduced quality of life, social disabilities and handicap. Many patients often find it hard to cope with pain in the trigeminal system. 5 April 2015 The trigeminal or 5th cranial nerve is divided into three divisions (Figure 2): The ophthalmic division (V1); The maxillary division (V2); and The mandibular division (V3). There are three sensory and one motor nuclei. The sensory nuclei (Figure 3) are arranged in a column which spans from the midbrain through the pons and medulla and into the upper cervical cord. The axons of these nuclei cross to the opposite side, ascending in the spinothalamic tract, to relay in the thalamic nuclei; from there, they end in the cerebral cortex. The sensory nucleus of CN V is connected to other motor nuclei of the pons and medulla. In addition, the descending sensory spinal tract receives somatic sensory fibres from other cranial nerves VII, IX and X. 1. Mesencephalic nucleus: proprioreceptive fibres for muscles of the face, orbit, mastication, tongue. The proprioceptive fibres of V arise from the muscles of mastication and the extra- ocular muscles. They terminate in the mesencephalic nucleus. This nucleus has connections to the motor nucleus of V. 2. The main sensory nucleus: located in the upper pons, lateral to the The trigeminal or 5th cranial nerve motor nucleus, is responsible for touch additionally The it receives trigeminal afferent nerve fibres exits from at the is divided into three divisions (Figure 2): sensation for all three trigeminal divisions. mid both pons the glossopharyngeal into the prepontine nerve cistern and and vagus The ophthalmic division (V1); The main sensory nucleus receives its passes nerve. anteriorly to the Meckel cave where The maxillary division (V2); and afferents (as the sensory root) from the its 4. fibres relay The motor forming nucleus Gasserian is located ganglion. in The mandibular division (V3). semilunar ganglion through the lateral part the upper pons The semilunar and innervates (Gasserian the muscles or There are three sensory and one of the pons ventral surface. Its axons cross trigeminal) of mastication, ganglion as well is as the mylohyoid great sensory motor nuclei. The sensory nuclei (Figure 3) to the other side, ascending to the thalamic ganglion and tensor of palati. CN V. It The contains motor the nucleus sensory is are arranged in a column which spans from nuclei to relay in the postcentral cerebral cell ventromedial bodies of the to the three sensory branches nucleus. of It the midbrain through the pons and medulla cortex. The descending sensory fibres from the lies near trigeminal the lateral nerve angle (the ophthalmic, of the fourth and into the upper cervical cord. The axons the semilunar ganglion course through the mandibular ventricle in the and rostral maxillary part divisions). of the pons. The The of these nuclei cross to the opposite side, pons and medulla in the spinal tract of V to ophthalmic mesencephalic and nucleus maxillary is in nerves the midbrain are purely ascending in the spinothalamic tract, to end in the nuclei of this tract (as far as the sensory. and receives The mandibular proprioceptive nerve fibres has from sensory all relay in the thalamic nuclei; from there, second cervical segment). and muscles motor of functions. mastication. they end in the cerebral cortex. The sensory The sensory nucleus, located The The Gasserian motor nucleus ganglion of V receives lies in nucleus of CN V is connected to other motor in the pons, is quite extensive. It receives a cortical depression fibres on for the voluntary petrous control apex, within of the nuclei of the pons and medulla. In addition, ordinary sensations from the main three a four dural muscles fold called of mastication the Meckel (masseter, cave. The the descending sensory spinal tract receives branches of the trigeminal. The ophthalmic sensory temporalis, roots medial of the pterygoid, three branches lateral of CN somatic sensory fibres from other cranial division is in the lower part of the nucleus, V pterygoid are received and anteriorly. the other four They muscles then pass are nerves VII, IX and X. and the mandibular branch is in the upper from the tensor the posterior veli palatini, aspect the of mylohyoid, the ganglion 1. Mesencephalic nucleus: part. to the the anterior pons. belly The motor of the root digastrics passes and under the proprioreceptive fibres for muscles of The large rostral head is the the tensor ganglion tympani). to join These the fibres sensory are division mostly the face, orbit, mastication, tongue. The main sensory nucleus. The caudal tapered of crossed. the mandibular It also receives nerve input and exits from the the proprioceptive fibres of V arise from the part is the spinal tract, which is continuous skull mesencephalic through foramen and sensory ovale. nuclei. The carotid The muscles of mastication and the extra- with substantia gelatinosa of Rolando in the plexus axons emerge contributes anteriorly sympathetic to the sensory fibres to root the ocular muscles. They terminate in the spinal cord. The spinal tract is the sensory gasserian from the lateral ganglion. surface of the pons. This mesencephalic nucleus. This nucleus has nucleus, primarily for pain and temperature. motor root The joins exracranial the semilunar part ganglion V then connections to the motor nucleus of ...
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... the Italian anatomist and physician 50% of the sensory cerebral cortex area Fallopius (1523–1562) discovered that is dedicated to the processing of orofacial these branches merged as one, that the sensation ( Figure 1), and therefore the 5th cranial nerve was created. In 1732, impact of trigeminal nerve injury may be the Danish anatomist Jacques-Bénigne significantly larger than in other areas of Winslow (1669–1760) ascribed the name the body. 2 ‘nerf trijumeau, referring to the three Damage to this sensory nerve can peripheral branches of this nerve, and the result in numbness (anaesthesia), tingling name ‘trigeminal nerve’ was born meaning altered sensation (paraesthesia), pain or ‘three twins. The trigeminal nerve is the a combination of the three in 50–70% of largest of the cranial nerves and the largest cases. 3 sensory nerve. It is a mixed sensory nerve Pain is common in sensory nerve injuries made up of both sensory and motor axons, and, due to the orofacial region being and it plays a particularly important role in affected, results in significant functional sensations of the face and head regions. problems including: eating, speaking, The unique nature of the kissing, drinking, applying make-up and trigeminal nerve is related to several shaving, in fact just about every social factors: function that we take for granted. 4 The head facial area is made up of The resultant psychological disability a variety of unique tissues such as the of chronic altered sensation or pain meninges, cornea, nasal sinuses, oral includes changes in self-perception, mucosa and tooth pulp, that require reduced quality of life, social disabilities specialized sensory innervations. 2 and handicap. Many patients often There is constant neural activity input find it hard to cope with pain in the related to orofacial function. trigeminal system. 5 April 2015 50% of the sensory cerebral cortex area is dedicated to the processing of orofacial sensation (Figure 1), and therefore the impact of trigeminal nerve injury may be significantly larger than in other areas of the body. 2 Damage to this sensory nerve can result in numbness (anaesthesia), tingling altered sensation (paraesthesia), pain or a combination of the three in 50–70% of cases. 3 Pain is common in sensory nerve injuries and, due to the orofacial region being affected, results in significant functional problems including: eating, speaking, kissing, drinking, applying make-up and shaving, in fact just about every social function that we take for granted. 4 The resultant psychological disability of chronic altered sensation or pain includes changes in self-perception, reduced quality of life, social disabilities and handicap. Many patients often find it hard to cope with pain in the trigeminal system. 5 April 2015 The trigeminal or 5th cranial nerve is divided into three divisions (Figure 2): The ophthalmic division (V1); The maxillary division (V2); and The mandibular division (V3). There are three sensory and one motor nuclei. The sensory nuclei (Figure 3) are arranged in a column which spans from the midbrain through the pons and medulla and into the upper cervical cord. The axons of these nuclei cross to the opposite side, ascending in the spinothalamic tract, to relay in the thalamic nuclei; from there, they end in the cerebral cortex. The sensory nucleus of CN V is connected to other motor nuclei of the pons and medulla. In addition, the descending sensory spinal tract receives somatic sensory fibres from other cranial nerves VII, IX and X. 1. Mesencephalic nucleus: proprioreceptive fibres for muscles of the face, orbit, mastication, tongue. The proprioceptive fibres of V arise from the muscles of mastication and the extra- ocular muscles. They terminate in the mesencephalic nucleus. This nucleus has connections to the motor nucleus of V. 2. The main sensory nucleus: located in the upper pons, lateral to the The trigeminal or 5th cranial nerve motor nucleus, is responsible for touch additionally The it receives trigeminal afferent nerve fibres exits from at the is divided into three divisions (Figure 2): sensation for all three trigeminal divisions. mid both pons the glossopharyngeal into the prepontine nerve cistern and and vagus The ophthalmic division (V1); The main sensory nucleus receives its passes nerve. anteriorly to the Meckel cave where The maxillary division (V2); and afferents (as the sensory root) from the its 4. fibres relay The motor forming nucleus Gasserian is located ganglion. in The mandibular division (V3). semilunar ganglion through the lateral part the upper pons The semilunar and innervates (Gasserian the muscles or There are three sensory and one of the pons ventral surface. Its axons cross trigeminal) of mastication, ganglion as well is as the mylohyoid great sensory motor nuclei. The sensory nuclei (Figure 3) to the other side, ascending to the thalamic ganglion and tensor of palati. CN V. It The contains motor the nucleus sensory is are arranged in a column which spans from nuclei to relay in the postcentral cerebral cell ventromedial bodies of the to the three sensory branches nucleus. of It the midbrain through the pons and medulla cortex. The descending sensory fibres from the lies near trigeminal the lateral nerve angle (the ophthalmic, of the fourth and into the upper cervical cord. The axons the semilunar ganglion course through the mandibular ventricle in the and rostral maxillary part divisions). of the pons. The The of these nuclei cross to the opposite side, pons and medulla in the spinal tract of V to ophthalmic mesencephalic and nucleus maxillary is in nerves the midbrain are purely ascending in the spinothalamic tract, to end in the nuclei of this tract (as far as the sensory. and receives The mandibular proprioceptive nerve fibres has from sensory all relay in the thalamic nuclei; from there, second cervical segment). and muscles motor of functions. mastication. they end in the cerebral cortex. The sensory The sensory nucleus, located The The Gasserian motor nucleus ganglion of V receives lies in nucleus of CN V is connected to other motor in the pons, is quite extensive. It receives a cortical depression fibres on for the voluntary petrous control apex, within of the nuclei of the pons and medulla. In addition, ordinary sensations from the main three a four dural muscles fold called of mastication the Meckel (masseter, cave. The the descending sensory spinal tract receives branches of the trigeminal. The ophthalmic sensory temporalis, roots medial of the pterygoid, three branches lateral of CN somatic sensory fibres from other cranial division is in the lower part of the nucleus, V pterygoid are received and anteriorly. the other four They muscles then pass are nerves VII, IX and X. and the mandibular branch is in the upper from the tensor the posterior veli palatini, aspect the of mylohyoid, the ganglion 1. Mesencephalic nucleus: part. to the the anterior pons. belly The motor of the root digastrics passes and under the proprioreceptive fibres for muscles of The large rostral head is the the tensor ganglion tympani). to join These the fibres sensory are division mostly the face, orbit, mastication, tongue. The main sensory nucleus. The caudal tapered of crossed. the mandibular It also receives nerve input and exits from the the proprioceptive fibres of V arise from the part is the spinal tract, which is continuous skull mesencephalic through foramen and sensory ovale. nuclei. The carotid The muscles of mastication and the extra- with substantia gelatinosa of Rolando in the plexus axons emerge contributes anteriorly sympathetic to the sensory fibres to root the ocular muscles. They terminate in the spinal cord. The spinal tract is the sensory gasserian from the lateral ganglion. surface of the pons. This mesencephalic nucleus. This nucleus has nucleus, primarily for pain and temperature. motor root The joins exracranial the semilunar part ganglion V then connections to the motor nucleus of V. The main sensory nucleus serves mostly for divides together into with three the main sensory branches root. (Figure 2): 2. The main sensory nucleus: discrimination sense. located in the upper pons, lateral to the 3. The spinal nucleus in the lower pons to the upper cervical cord is responsible for pain and temperature; The trigeminal or 5th cranial nerve motor nucleus, is responsible for touch additionally The it receives trigeminal afferent nerve fibres exits from at the is divided into three divisions (Figure 2): sensation for all three trigeminal divisions. mid both pons the glossopharyngeal into the prepontine nerve cistern and and vagus The ophthalmic division (V1); The main sensory nucleus receives its passes nerve. anteriorly to the Meckel cave where The maxillary division (V2); and afferents (as the sensory root) from the its 4. fibres relay The motor forming nucleus Gasserian is located ganglion. in The mandibular division (V3). semilunar ganglion through the lateral part the upper pons The semilunar and innervates (Gasserian the muscles or There are three sensory and one of the pons ventral surface. Its axons cross trigeminal) of mastication, ganglion as well is as the mylohyoid great sensory motor nuclei. The sensory nuclei (Figure 3) to the other side, ascending to the thalamic ganglion and tensor of palati. CN V. It The contains motor the nucleus sensory is are arranged in a column which spans from nuclei to relay in the postcentral cerebral cell ventromedial bodies of the to the three sensory branches nucleus. of It the midbrain through the pons and medulla cortex. The descending sensory fibres from the lies near trigeminal the lateral nerve angle (the ophthalmic, of the fourth and into the upper cervical cord. The axons the semilunar ganglion course through the ...
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... receives its passes nerve. anteriorly to the Meckel cave where The maxillary division (V2); and afferents (as the sensory root) from the its 4. fibres relay The motor forming nucleus Gasserian is located ganglion. in The mandibular division (V3). semilunar ganglion through the lateral part the upper pons The semilunar and innervates (Gasserian the muscles or There are three sensory and one of the pons ventral surface. Its axons cross trigeminal) of mastication, ganglion as well is as the mylohyoid great sensory motor nuclei. The sensory nuclei (Figure 3) to the other side, ascending to the thalamic ganglion and tensor of palati. CN V. It The contains motor the nucleus sensory is are arranged in a column which spans from nuclei to relay in the postcentral cerebral cell ventromedial bodies of the to the three sensory branches nucleus. of It the midbrain through the pons and medulla cortex. The descending sensory fibres from the lies near trigeminal the lateral nerve angle (the ophthalmic, of the fourth and into the upper cervical cord. The axons the semilunar ganglion course through the mandibular ventricle in the and rostral maxillary part divisions). of the pons. The The of these nuclei cross to the opposite side, pons and medulla in the spinal tract of V to ophthalmic mesencephalic and nucleus maxillary is in nerves the midbrain are purely ascending in the spinothalamic tract, to end in the nuclei of this tract (as far as the sensory. and receives The mandibular proprioceptive nerve fibres has from sensory all relay in the thalamic nuclei; from there, second cervical segment). and muscles motor of functions. mastication. they end in the cerebral cortex. The sensory The sensory nucleus, located The The Gasserian motor nucleus ganglion of V receives lies in nucleus of CN V is connected to other motor in the pons, is quite extensive. It receives a cortical depression fibres on for the voluntary petrous control apex, within of the nuclei of the pons and medulla. In addition, ordinary sensations from the main three a four dural muscles fold called of mastication the Meckel (masseter, cave. The the descending sensory spinal tract receives branches of the trigeminal. The ophthalmic sensory temporalis, roots medial of the pterygoid, three branches lateral of CN somatic sensory fibres from other cranial division is in the lower part of the nucleus, V pterygoid are received and anteriorly. the other four They muscles then pass are nerves VII, IX and X. and the mandibular branch is in the upper from the tensor the posterior veli palatini, aspect the of mylohyoid, the ganglion 1. Mesencephalic nucleus: part. to the the anterior pons. belly The motor of the root digastrics passes and under the proprioreceptive fibres for muscles of The large rostral head is the the tensor ganglion tympani). to join These the fibres sensory are division mostly the face, orbit, mastication, tongue. The main sensory nucleus. The caudal tapered of crossed. the mandibular It also receives nerve input and exits from the the proprioceptive fibres of V arise from the part is the spinal tract, which is continuous skull mesencephalic through foramen and sensory ovale. nuclei. The carotid The muscles of mastication and the extra- with substantia gelatinosa of Rolando in the plexus axons emerge contributes anteriorly sympathetic to the sensory fibres to root the ocular muscles. They terminate in the spinal cord. The spinal tract is the sensory gasserian from the lateral ganglion. surface of the pons. This mesencephalic nucleus. This nucleus has nucleus, primarily for pain and temperature. motor root The joins exracranial the semilunar part ganglion V then connections to the motor nucleus of V. The main sensory nucleus serves mostly for divides together into with three the main sensory branches root. (Figure 2): 2. The main sensory nucleus: discrimination sense. located in the upper pons, lateral to the 3. The spinal nucleus in the lower pons to the upper cervical cord is responsible for pain and temperature; The trigeminal or 5th cranial nerve motor nucleus, is responsible for touch additionally The it receives trigeminal afferent nerve fibres exits from at the is divided into three divisions (Figure 2): sensation for all three trigeminal divisions. mid both pons the glossopharyngeal into the prepontine nerve cistern and and vagus The ophthalmic division (V1); The main sensory nucleus receives its passes nerve. anteriorly to the Meckel cave where The maxillary division (V2); and afferents (as the sensory root) from the its 4. fibres relay The motor forming nucleus Gasserian is located ganglion. in The mandibular division (V3). semilunar ganglion through the lateral part the upper pons The semilunar and innervates (Gasserian the muscles or There are three sensory and one of the pons ventral surface. Its axons cross trigeminal) of mastication, ganglion as well is as the mylohyoid great sensory motor nuclei. The sensory nuclei (Figure 3) to the other side, ascending to the thalamic ganglion and tensor of palati. CN V. It The contains motor the nucleus sensory is are arranged in a column which spans from nuclei to relay in the postcentral cerebral cell ventromedial bodies of the to the three sensory branches nucleus. of It the midbrain through the pons and medulla cortex. The descending sensory fibres from the lies near trigeminal the lateral nerve angle (the ophthalmic, of the fourth and into the upper cervical cord. The axons the semilunar ganglion course through the mandibular ventricle in the and rostral maxillary part divisions). of the pons. The The of these nuclei cross to the opposite side, pons and medulla in the spinal tract of V to ophthalmic mesencephalic and nucleus maxillary is in nerves the midbrain are purely ascending in the spinothalamic tract, to end in the nuclei of this tract (as far as the sensory. and receives The mandibular proprioceptive nerve fibres has from sensory all relay in the thalamic nuclei; from there, second cervical segment). and muscles motor of functions. mastication. they end in the cerebral cortex. The sensory The sensory nucleus, located The The Gasserian motor nucleus ganglion of V receives lies in nucleus of CN V is connected to other motor in the pons, is quite extensive. It receives a cortical depression fibres on for the voluntary petrous control apex, within of the nuclei of the pons and medulla. In addition, ordinary sensations from the main three a four dural muscles fold called of mastication the Meckel (masseter, cave. The the descending sensory spinal tract receives branches of the trigeminal. The ophthalmic sensory temporalis, roots medial of the pterygoid, three branches lateral of CN somatic sensory fibres from other cranial division is in the lower part of the nucleus, V pterygoid are received and anteriorly. the other four They muscles then pass are nerves VII, IX and X. and the mandibular branch is in the upper from the tensor the posterior veli palatini, aspect the of mylohyoid, the ganglion 1. Mesencephalic nucleus: part. to the the anterior pons. belly The motor of the root digastrics passes and under the proprioreceptive fibres for muscles of The large rostral head is the the tensor ganglion tympani). to join These the fibres sensory are division mostly the face, orbit, mastication, tongue. The main sensory nucleus. The caudal tapered of crossed. the mandibular It also receives nerve input and exits from the the proprioceptive fibres of V arise from the part is the spinal tract, which is continuous skull mesencephalic through foramen and sensory ovale. nuclei. The carotid The muscles of mastication and the extra- with substantia gelatinosa of Rolando in the plexus axons emerge contributes anteriorly sympathetic to the sensory fibres to root the ocular muscles. They terminate in the spinal cord. The spinal tract is the sensory gasserian from the lateral ganglion. surface of the pons. This mesencephalic nucleus. This nucleus has nucleus, primarily for pain and temperature. motor root The joins exracranial the semilunar part ganglion V then connections to the motor nucleus of V. The main sensory nucleus serves mostly for divides together into with three the main sensory branches root. (Figure 2): 2. The main sensory nucleus: discrimination sense. located in the upper pons, lateral to the 3. The spinal nucleus in the lower pons to the upper cervical cord is responsible for pain and temperature; The trigeminal nerve exits at the mid pons into the prepontine cistern and passes anteriorly to the Meckel cave where its fibres relay forming Gasserian ganglion. The semilunar (Gasserian or trigeminal) ganglion is the great sensory ganglion of CN V. It contains the sensory cell bodies of the three branches of the trigeminal nerve (the ophthalmic, mandibular and maxillary divisions). The ophthalmic and maxillary nerves are purely sensory. The mandibular nerve has sensory and motor functions. The Gasserian ganglion lies in a depression on the petrous apex, within a dural fold called the Meckel cave. The sensory roots of the three branches of CN V are received anteriorly. They then pass from the posterior aspect of the ganglion to the pons. The motor root passes under the ganglion to join the sensory division of the mandibular nerve and exits the skull through foramen ovale. The carotid plexus contributes sympathetic fibres to the gasserian ganglion. The exracranial part V then divides into three main branches (Figure ...
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... latter divides into internal and external nasal branches) and the infratrochlear nerve ( Figure 4a, b). 2. Maxillary division (V2): This passes in the lateral wall of the cavernous sinus then through the foramen rotundum to exit the skull. Then it crosses the pterygopalatine fossa and enters the orbit through the inferior orbital fissure and the infraorbital canal. It emerges through the infraorbital foramen to become the infraorbital nerve. Hence the orbital blow out fracture is associated with a loss of sensation over the maxilla (Figure 4a, b). 3. Mandibular division (V3): This passes through the foramen ovale and gives motor supply to the muscles of mastication and sensory supply to the auriculotemporal region, lower face, mouth and dentition. Pain signals originating in the orofacial region are carried through the trigeminal (Gasserian) ganglion on to the trigeminal spinal tract where they then synapse within the subnucleus caudalis (Figure 3). 6 The subnucleus caudalis (SC), which exhibits functional and morphologic similarities to the spinal cord dorsal horn, relays the signals to the thalamus where they synapse again and move on to higher cortical centres. 6 Nociceptive neurons of the subnucleus caudalis converge from the tooth pulp, temporomandiblular joints and muscles of mastication, oral cavity and facial skin. This access of multiple afferent inputs onto a neuron is known as convergence . Convergence is believed to be one of the reasons responsible for the extensive degree of pain referral seen within the orofacial region. While trigeminal system pain has not been studied nearly as extensively as spinal cord mediated pain, it is believed that the mechanisms of pain modulation and conduction pathways are very similar. 7,8 The central axons of the trigeminal nerve terminate in the trigeminal brainstem complex, which ranges from the midbrain to the medulla where it merges seamlessly with the upper cervical spinal cord. The trigeminal brainstem complex is in fact made up of several separate nuclei, including the principal, spinal, paratrigeminal, mesencephalic and ...
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... signals originating in the orofacial region are carried through the trigeminal (Gasserian) ganglion on to the trigeminal spinal tract where they then synapse within the subnucleus caudalis (Figure 3). 6 The subnucleus caudalis (SC), which exhibits functional and morphologic similarities to the spinal cord dorsal horn, relays the signals to the thalamus where they synapse again and move on to higher cortical centres. ...
Citations
... Posteriorly, the margin remains the line vertex-external auditory meatus-chin. The importance of the trigeminal sensory innervation is very high-approximately 50% of the cortical representation of all sensory inputs from the body comes from the trigeminal system [21]. Trigeminal primary afferents are dendrites of pseudounipolar neurons in trigeminal (semilunar, Gasserian) ganglion and mesencephalic nucleus [22]. ...
(1) Background and Objectives: The aim of this narrative review was to analyze the neuroanatomical and neurophysiological basis of cervicogenic pain in cervico-cranial pain syndromes, focusing particularly on cervico-orofacial syndromes as a background for the proper diagnosis and non-surgical treatment. Relevant literature on the topic from past 120 years has been surveyed. (2) Material and Methods: We surveyed all original papers, reviews, or short communications published in the English, Spanish, Czech or Slovak languages from 1900 to 2020 in major journals. (3) Results: The cervicogenic headache originates from the spinal trigeminal nucleus where axons from the C1–C3 cervical spinal nerves and three branches of the trigeminal nerve converge (trigeminocervical convergence) at the interneurons that mediate cranio-cervical nociceptive interactions. The role of the temporomandibular joint in the broad clinical picture is also important. Despite abundant available experimental and clinical data, cervicogenic orofacial pain may be challenging to diagnose and treat. Crucial non-surgical therapeutic approach is the orthopedic manual therapy focused on correction of body posture, proper alignment of cervical vertebra and restoration of normal function of temporomandibular joint and occlusion. In addition, two novel concepts for the functional synthesis of cervico-cranial interactions are the tricentric concept of mouth sensorimotor control and the concept of a cervicogenic origin of bruxism. (4) Conclusions: Understanding the basis of neuroanatomical and neurophysiological neuromuscular relations enables an effective therapeutic approach based principally on orthopedic manual and dental occlusal treatment.
... In order to comprehend the orthodontic movements that may cause IAN damage, one must grasp the basic anatomical course of the IAN (branch of the mandibular nerve V3). The mylohyoid and lingual nerves branch from the main trunk of the mandibular nerve before it enters the mandibular foramen, thus the tongue, lingual mucosa and lower mental symphysis regions were not affected in the included studies of this review [23]. Figure 4 shows the intraoral dermatomes that IAN innervates including its mental nerve (branch of the IAN) as described by Renton and Egbuniwe [23]. ...
... The mylohyoid and lingual nerves branch from the main trunk of the mandibular nerve before it enters the mandibular foramen, thus the tongue, lingual mucosa and lower mental symphysis regions were not affected in the included studies of this review [23]. Figure 4 shows the intraoral dermatomes that IAN innervates including its mental nerve (branch of the IAN) as described by Renton and Egbuniwe [23]. ...
Background:
Neurosensory impairment is a common complication following inferior alveolar nerve (IAN) damage.
Objective:
To document and report the various causes, diagnosis, and management of IAN damage secondary to orthodontic treatment.
Methods:
An electronic search for studies that reported IAN damage in patients undergoing orthodontic treatment was performed up to July 15, 2020 using MEDLINE, EMBASE, and PubMed databases. Descriptive analyses and linear regression model were performed.
Results:
A total of 15 case reports were identified including 16 patients with an overall mean age of 23.3. All the included studies reported temporary sensory alterations which manifested as anesthesia (19%, n = 3), paresthesia (75%, n = 12), or combined (6%, n = 1). The majority of cases managed by stopping the orthodontic force (75%, n = 12), followed by appliance adjustments (19%, n = 3), providing a bite plate (13%, n = 2), and/or providing pharmacological management (38%, n = 6). Full recovery median duration reported in all cases following the aforementioned managements was 17.5 days.
Conclusions:
IAN damage secondary to orthodontic treatment is emerging in the literature in recent years. Identifying high risk patients with close proximity to the IAN canal is a must to formulate a proper treatment plan to avoid such complications.
... Lastly, in the third year, they receive 4 hours of "anatomy in diagnostic imaging" (2 hours of lectures and 2 hours of laboratory). From the fourth year, there is no formal anatomy teaching, but the PBL includes additional anatomy learning material such as scientific articles (Renton and Obi, 2015;Kerai and Ganesan, 2018) and book references (Martini et al., 2015;Norton, 2016). Occasionally, CBCT images are used during "diagnostic imaging" and "clinical-pathological conference" sessions in senior years. ...
Learning bone anatomy of the skull is a complex topic involving three‐dimensional information. The impact of the use of human dry skulls and cone beam computed tomography (CBCT) imaging was investigated in the teaching of undergraduate dental students. Sixty‐four first‐year students in the University of Hong Kong were randomly divided into eight groups. Four teaching methods were tested: (1) CBCT followed by standard lecture, (2) CBCT followed by lecture with skulls, (3) standard lecture followed by CBCT, and (4) lecture with skulls followed by CBCT. After each, students were given a multiple‐choice questionnaire to assess their objective learning outcome (20 questions) and a questionnaire for their subjective satisfaction (10 statements). Surveys were assessed with Cronbach's alpha, Kendall's tau‐b, and principal components analysis. Data were analyzed with Student's t‐test and a one‐way ANOVA (significance α = 0.05). Standard lecture followed by CBCT showed the highest learning outcome score (81.6% ± 14.1%), but no significant difference was present among four teaching methods. Cone beam computed tomography followed by lecture with skulls scored the highest overall subjective satisfaction (4.9 ± 0.8 out of 6), but no significant difference was present among teaching methods. Nevertheless, students' perception of learning was positively influenced by the use of skulls (P = 0.018). The timing of administration of the CBCT did not affect students' subjective satisfaction or objective learning outcome. Students perceived to learn more by using skulls, but their objective learning outcomes were not significantly affected. A discrepancy seems to exist between students' perception of learning and their effective performance.
... Dental noxious input passes to the brain via the trigeminal nerve. Trigeminal nociceptive information is conveyed to the trigeminal nucleus caudalis (Vc), as the pivotal site for primarily processing, and relays to second-order neurons (Renton & Egbuniwe 2015, Sessle 2017. ...
Aim:
To assess the effects of central administration of α-pinene alone and in combination with either bicuculline or naloxone, as GABA A and μ opioid receptor antagonists respectively, on capsaicin-induced dental pulp stimulation in rats.
Methodology:
Forty eight adult male Wistar rats aged 2 months (230-270 g) were cannulated via their lateral ventricles for the central administration of the drugs. α-Pinene was injected at 0.1, 0.2 and 0.4 μM. Then, dental pulp stimulation was induced by intradental application of capsaicin solution (100 μg), and nociceptive scores were recorded for up to 40 min. For investigation of the anti-inflammatory effects of α-pinene, expression of COX-2 in the sub nucleolus caudalis (Vc) of rats was determined using immunofluorescence staining. Non-parametric repeated measure Friedman and Kruskal-Wallis tests as well as parametric one-way analysis of variance were used for the statistical analysis.
Results:
α-Pinene at 0.2 μM and 0.4 μM was able to decrease capsaicin-induced nociception. Moreover, there was a significant increase in the expression of COX-2 positive cells in the Vc of capsaicin treated rats (p < 0. 01). This effect was prohibited by α-pinene (0.4μM). Co-administration of bicuculline (1μg/rat) or naloxone (6μg/rat) with α-pinene (0.4μM), however, prevented the inhibitory effects of α-pinene on both capsaicin-induced pulp nociception and COX-2 over-expression.
Conclusions:
α-Pinene exhibited significant curable effects on capsaicin-induced pulpal nociception and inflammation mainly via pharmacological interfacing with GABA-A and μ opioid receptors. This article is protected by copyright. All rights reserved.
... Il constitue un nerf complexe dont le territoire d'élection est très étendu, correspondant au premier arc branchial. Schématiquement, le nerf V innerve le massif crânio-facial en avant d'une ligne oblique allant du vertex en passant par le tragus et le bord inférieur de la mandibule en avant de l'angle (Figs. 6 et 7) [1,9,10,11,12,18,20,21,23,28,29,30,35]. Nous renvoyons le lecteur aux références citées à la fin de cet article pour la description précise du trajet facial [4,14,15,18,21,25,28,29,31]. ...
... Les fibres nociceptives pulpaires, cornéennes, méningées et celles de l'ATM sont essentiellement des fibres de petit diamètre (importance des fibres C). Le schéma conclusif se focalise sur les plexus dentaires supérieurs et inférieurs dont le potentiel nociceptif est universellement reconnu comme étant redoutable [1,12,13,21,28,30,34,35], (Fig. 8). La distribution des différentes branches terminales des nerfs V2 et V3s (racine sensitive du nerf V3) dans la cavité orale intéresse plus particulièrement la pratique odonto-stomatologique [10,14,15,21,30] (Fig. 9). ...
... Le schéma conclusif se focalise sur les plexus dentaires supérieurs et inférieurs dont le potentiel nociceptif est universellement reconnu comme étant redoutable [1,12,13,21,28,30,34,35], (Fig. 8). La distribution des différentes branches terminales des nerfs V2 et V3s (racine sensitive du nerf V3) dans la cavité orale intéresse plus particulièrement la pratique odonto-stomatologique [10,14,15,21,30] (Fig. 9). Une douleur trigéminale doit être traitée cliniquement de façon précoce. ...
... Despite the present findings, the use of questionnaires to aid in the diagnosis of neuropathic pain has been employed in other areas of medicine. 21,22 Based on the difference of the local anatomy and function of the trigeminal somatosensory system, [37][38][39][40][41][42][43] it is reasonable to think that a questionnaire developed to assess spinally mediated neuropathic pain may not be acceptable for pain presenting within the trigeminal innervation territory (face, oral cavity). Therefore, objective measurements of psychometric properties need to be developed to validate or not such a rationale. ...
Objective:
To evaluate the accuracy of a questionnaire modified for the identification of intraoral pain with neuropathic characteristics in a clinical orofacial pain sample population.
Method and materials:
136 participants with at least one of four orofacial pain diagnoses (temporomandibular disorders [TMD, n = 41], acute dental pain [ADP, n = 41], trigeminal neuralgia [TN, n = 19], persistent dentoalveolar pain disorder [PDAP, n = 14]) and a group of pain-free controls (n = 21) completed the modified S-LANSS, a previously adapted version of the original questionnaire devised to detected patients suffering from intraoral pain with neuropathic characteristics. Psychometric properties (sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV]) were calculated in two analyses with two different thresholds: (1) Detection of pain with neuropathic characteristics: PDAP + TN were considered positive, and TMD + ADP + controls were considered negative per gold standard (expert opinion). (2) Detection of PDAP: PDAP was considered positive and TMD + ADP were considered negative per gold standard. For both analyses, target values for adequate sensitivity and specificity were defined as ≥ 80%.
Results:
For detection of orofacial pain with neuropathic characteristics (PDAP + TN), the modified S-LANSS presented with the most optimistic threshold sensitivity of 52% (95% confidence interval [CI], 34-69), specificity of 70% (95% CI, 60-79), PPV of 35% (95% CI, 22-51), and NPV of 82% (95% CI, 72-89). For detection of PDAP only, with the most optimistic threshold sensitivity was 64% (95% CI, 35-87), specificity 63% (95% CI, 52-74), PPV 23% (95% CI, 11-39) and NPV 91% (95% CI, 81-97).
Conclusion:
Based on a priori defined criteria, the modified S-LANSS did not show adequate accuracy to detect intraoral pain with neuropathic characteristics in a clinical orofacial pain sample.
... While the motor cortex and central pattern generators regulate cyclic and purposeful muscle contractions, complex reflex patterns within the brainstem and spinal cord exchange information between different parts of the system; and depend on a vast amount of sensory information from the joint capsules, retrodiscal tissues, tongue, periodontal, pharyngeal and laryngeal tissues, and associated muscles, ligaments and fascia (Renton and Egbuniwe, 2015;Yin et al., 2007). Reflex systems assimilate this and initiate muscle contractions in a way that supplements supra-spinal control, but their ability to respond to unexpected changes within the system is incomplete as even the fastest monosynaptic reflex experiences a time-delay (Brown and Loeb, 2000;Turvey and Fonseca, 2014). ...
The temporo-mandibular joint is a characteristic feature of mammalian development, and essential to mastication and speech, yet it causes more problems than any other joint in the body and remains the least understood. While it is generally accepted that the normal joint is loaded under compression, the problems and controversies surrounding this view remain unresolved and the disparity in opinion over its treatment continues. Although difficulties in the acquisition of reliable information have undoubtedly contributed to this situation, it is now considered that deficits in neural control and shortcomings in the underlying biomechanical theory and analysis have also played a part, and that a re-assessment from a different perspective could resolve these.
... The masticatory apparatus is thus a kinematically and mechanically indeterminate system, with the complex architecture of these muscles contributing to the great variation in motor activity and adaptability to changing functional demands (Grünheid et al., 2009;Hiraba et al., 2000;Murray et al., 2001). While higher centres within the brain initiate and regulate purposeful movements, they are dependent on a huge amount of sensory information from the TMJ, tongue, periodontal, pharyngeal and laryngeal tissues, and associated muscles, ligaments and fascia, which means that the number of factors involved in even the simplest of movements soon becomes enormous (Renton and Egbuniwe, 2015;Turvey and Fonseca, 2014;Yin et al., 2007) and that any meaningful analysis must substantially reduce them to a manageable level (Koolstra, 2003;Pileicikiene and Surna, 2004); and there has lain the problem. ...
The temporo-mandibular joint causes more problems than any other in the body and is the least understood with the high incidence of associated symptomatology remaining a major cause for concern. This lack of knowledge is partly due to the difficulties in acquiring information as it is not easy to access and practical and ethical constraints have ensured the almost complete absence of reliable in vivo data on joint loading and muscle forces. Whilst the issue of joint compression was debated throughout much of the twentieth-century, it is now considered that short-comings in the underlying biomechanical theory and analysis have contributed to this uncertainty and stifled progress, and that a reassessment of mandibular motion from a different perspective could resolve this.
Background
Although the essential components of pain pathways have been identified, a thorough comprehension of the interactions necessary for creating focused treatments is still lacking. Such include more standardised methods for measuring pain in clinical and preclinical studies and more representative study populations.
Objective
This review describes the essential neuroanatomy and neurophysiology of pain nociception and its relation with currently available neuroimaging methods focused on health professionals responsible for treating pain.
Methods
Conduct a PubMed search of pain pathways using pain-related search terms, selecting the most relevant and updated information.
Results
Current reviews of pain highlight the importance of their study in different areas from the cellular level, pain types, neuronal plasticity, ascending, descending, and integration pathways to their clinical evaluation and neuroimaging. Advanced neuroimaging techniques such as fMRI, PET, and MEG are used to better understand the neural mechanisms underlying pain processing and identify potential targets for pain therapy.
Conclusion
The study of pain pathways and neuroimaging methods allows physicians to evaluate and facilitate decision-making related to the pathologies that cause chronic pain. Some identifiable issues include a better understanding of the relationship between pain and mental health, developing more effective interventions for chronic pain's psychological and emotional aspects, and better integrating data from different neuroimaging modalities for the clinical efficacy of new pain therapies.
This study examined the effects of delivery mode on the response to inflammatory pulpal pain and pain-induced changes in cognitive performance in adult rats. Experiments were done on rats born by vaginal or caesarean section (C-section) delivery. Dental pulp was irritated by intradental capsaicin (100 µg) application and then nociceptive scores were recorded for 40 min. Spatial and passive avoidance learning and memory were assessed using Morris Water Maze (MWM) and shuttle box tools, respectively. Additionally, in vivo recording of field excitatory postsynaptic potential (fEPSP) in the CA1 of the hippocampus, was used to verify synaptic plasticity. Capsaicin produced more significant nociceptive behaviour in vaginally delivered rats compared to C-section (P<0.01). C-section delivered rats show better performance in both MWM and shuttle box tests. Likewise, C-section rats had greater fEPSP slopes compared to the vaginally delivered group (P<0.05). Capsaicin impairs cognitive performance in rats born by each delivery route. However, capsaicin effects were more significant in rats delivered vaginally than by C-section. Overall, C-section delivered rats show lower sensitivity to capsaicin-evoked pulpal nociception and better cognitive performance than vaginally delivered rats. These effects are in part mediated by reduced neuroinflammation and enhanced neuronal synaptic plasticity following C-section delivery.
