1. 1. CRANIAL NERVES PART 1
2. 2. CONTENTS Introduction. Organization of Nervous System. Related Terminologies. Cranial Nerves. Detailed study of V. Trigeminal nerve VII. Facial nerve IX. Glossopharyngeal nerve X. Vagus nerve XII. Hypoglossal nerve References.
3. 3. INTRODUCTION The nervous system is the most important organization which controls and integrates the different bodily functions and likewise maintains a stability of the internal environment despite extreme changes in the external environment. This system is absolutely necessary for the reception , storage and release of different sensory and motor informations for regulating or initiating a particular behaviour of the individual. It is a very complicated system; structures and organs are specialised for different specific purposes.
4. 4. NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM BRAIN SPINAL CORD SOMATIC AUTONOMOUS CRANIAL NERVES 12 PAIRS SYMPATHETI C PARASYMPATHETI C SPINAL NERVES 31 PAIRS ORGANIZATION OF THE NERVOUS SYSTEM
5. 5. RELATED TERMINOLOGIES NEURON: It is the structural and functional unit of the nervous system and consists of a nerve cell body with all its processes.
6. 6. NUCLEUS: A mass of grey matter, composed of nerve cells, in any part of the brain or spinal cord. GANGLION: It is a group of nerve cell bodies situated outside the brain and spinal cord. Cranial nerve nuclei as projected on to the dorsal aspect of the brain stem.
7. 7. TRACT: A bundle or group of nerve fibers in the brain or spinal cord. NERVE: A bundle of neuronal processes outside the central nervous system. PLEXUS: A network or interjoining of nerves.
8. 8. VISCERAL NERVES: Nerves which supply (or bring information from) the different viscera, the organs within the body cavity. These nerves are better known as autonomic nerves. SOMATIC NERVES: They supply somatic structures (skin and muscles).
9. 9. AFFERENT NERVE: These fibres bring information from the periphery to the CNS. (or ) from one part of the CNS to another part. (e. g. from the spinal cord to the brain). All afferent nerves are sensory. EFFERENT NERVE: Carry commands to the organ supplied. (or) they carry command from one part of the CNS to another part (e.g. from brain to spinal cord). All efferent nerves are motor.
10. 10. GENERAL: Refers to stimuli conducted throughout the entire body, common to both cranial and spinal nerves.Eg: touch, pressure, vibration, pain, thermal sensation and proprioception . SPECIAL: Afferent information is encoded by highly specialized sense organs and transmitted to the brain in certain cranial nerves (I, II, VII, VIII, IX) Ex; olfaction, vision, taste, hearing and vestibular function.
11. 11. Cranial nerves I.Olfactory nerve II.Optic nerve III.Occlumotor nerve IV.Trochlear nerve V.Trigeminal nerve VI.Abducens nerve VII.Facial nerve VIII.Vestibulocochlear nerve IX.Glossopharyngeal nerve X.Vagus nerve XI.Accessory nerve XII.Hypoglossal nerve
12. 12. Classification Sensory cranial nerves I. Olfactory II. Optic VII. Vestibulocochlear Motor cranial nerves III. Occluomotor IV. Trochlear VI. Abducent XI. Accessory XII. Hypoglossal Mixed cranial nerves V. Trigeminal VII. Facial IX. Glossopharyngeal X. Vagus
13. 13. TRIGEMINAL NERVE It is the fifth (V) cranial nerve The largest cranial nerve It is a mixed nerve, contains both sensory & motor fibres. It is attached to the ventral surface of the pons, near its upper border, by a large sensory and a small motor, root---the latter being placed medial and anterior to the former.
14. 14. Sensory and motor root of the trigeminal nerve The two roots then enter the middle cranial fossa.
15. 15. Superior view of the middle cranial fossa showing some of its contents
16. 16. Sensory root of trigeminal nerve The fibres of this root arise from the semilunar (gasserian) ganglion. They enter the brain stem through the side of pons. Semilunar ganglion: neural crest Unipolar neurons Crescent shaped Meckels cavity Peripheral & central processes
17. 17. Peripheral branches V1 ophthalmic V2 maxillary V3 mandibular divisions Central branches (sensory roots) ascending descending branches
18. 18. Motor root of trigeminal nerve consists of fibres that arise in the motor nucleus located in upper pons Pons medial side of semilunar ganglion foramen ovale to join mandibular division immediately below the base of the skull. Motor supply to the muscles of mastication masticator nerve.
19. 19. Nuclei of the trigeminal nerve Sensory nuclei Mesencephalic Primary sensory Spinal Motor nucleus
20. 20. Mesencephalic nucleus Consists of afferent fibres that accompany the fibres of the motor root. Entering the pons from the peripheral distribution of the of the mandibular division of the trigeminal nerve,these fibres ascend to the mesencephalic nucleus of the trigeminal nerve. This nucleus serves as an afferent station that receives proprioceptive impulses from the temporomandibular joint,the periodontal membrane,the maxillary and mandibular teeth, and the hard palate. The mesencephalic nucleus also receives afferent impulses from stretch receptors in the muscles of
21. 21. Primary sensory nucleus Lies in the upper part of the pons. Lateral to the motor nucleus. Mainly concerned in mediation of poprioceptive impulses touch and preassure(from the region to which the trigeminal nerve is distributed).
22. 22. Spinal (bulbospinal) nucleus: Caudal to the sensory nucleus. Forms ventral trigeminothalamic tract. Convey pain & temp from the entire Trigeminal area.
23. 23. Motor nucleus Lies in the upper part of the pons in the dorsal part. It is situated mesial to the main sensory nucleus
24. 24. Functional components General somatic affarent: transmit exteroceptive impulses of touch pain and thermal senses from the skin of the face and forehead, mucous membranes of nasal cavities, oral cavity, nasal sinuses, and floor of the mouth; the teeth; the anterior two thirds of the tongue; and extensive portions of the cranial dura.
25. 25. Proprioceptive impulses (deep preassure and kinesthesis) are conveyed from the teeth, periodontium, hard palate and temporomandibular joint receptors. The nerve also conveys afferent fibers from stretch receptors in the muscles of mastication.
26. 26. Special viceral efferent: fibers innervate the muscles of mastication, the tensor tympani and the tenor veli palatini muscles, anterior belly of digastric.
27. 27. Divisions of the trigeminal nerve Opthalmic V1 Maxillary V2 Mandibular V3
28. 28. Opthalmic division V1 First division of the trigeminal nerve Smallest of the three branches Its fibres are sensory,or afferent, from the scalp, the skin of the forehead, the upper eyelid lining the frontal sinus, the conjunctiva of the eyeball, the lacrimal gland, and the skin of the lateral angle of the eye. It also transmits sensory impulses from the sclera of the eye ball & the lining of the ethmoid cells. Leaves ant. medial part of ganglion cavernous sinus superior orbital fissure orbit In the middle cranial fossa nervus tentori dura communication br. Occlumotor Trochlear Abducent
29. 29. Branche s Lacrimal Frontal Nasocilliary
30. 30. Lacrimal nerve Smallest of the three branches It passes in to the orbit at the lateral angle of the superior orbital fissure. Then courses in an anterolateral direction to reach the lacrimal gland. Structures supplied Lacrimal gland Sensory from the skin of upper eyelid & Lateral part of Eyebrow region. Sensory from the conjunctiva of the lateral part of upper eyelid
31. 31. Frontal nerve Largest of three branches. Direct continuation of the ophthalmic division. It enters the orbit by way of the superior orbital fissure. At about the middle of the orbit the frontal nerve divides in to two branches: supraorbital and supratrochlear nerves. Supraorbital nerve Supratrochlear nerve Largest branch of frontal n. Smallest branch of frontal n. Leave the orbit through supra orbital foramen Passes toward the medial angle of the orbit Sensory from the medial part of the upper eyelid , the skin of the forehead and scalp to the vertex of the skull Sensory from the medial part of the upper eyelid and the lower medial part of the forehead Sensory from the lining of the frontal sinus Sensory from the conjuctivae of the upper eyelid
32. 32. Supra-trochlear : Smaller Supplies: conjunctiva and skin of medial aspect of upper eyelid. Lower and mesial aspects of forehead. Supra-orbital : Larger Supplies : Upper eyelid Skin of the forehead and scalp as far back as lambdoid suture. FRONTAL NERVE Medial branch, supraorbital nerve Supratrochlear nerve Frontal nerve Ophthalmic nerve Lateral branch, supraorbital nerve
33. 33. Nasocilliary nerve It enters the orbit through the superior orbital fissure. Branches In the orbit In the nasal cavity On the face In nasal cavity: Supply mucous membrane lining the cavity. Terminal branches on the face: Sensory to skin of medial part of both eyelids, lacrimal sac, lacrimal caruncle. Also skin over the side of the bridge of the nose.
34. 34. NASOCILLIARY NERVE Enters orbit through Superior orbital fissure Branches Short ciliary nerves : sensory fibres from ciliary ganglion to eyeball Long ciliary nerves : iris and cornea Infratrochlear nerve : skin of both eyelids,adjoining sides of nose,lacrimal sac and caruncle Posterior ethmoidal nerve : ethmoidal and sphenoidal sinuses Anterior ethmoidal nerve : medial and lateral internal nasal branches Infratrochlear nerve Short ciliary nerves Posterior ethmoidal nerve Anterior ethmoidal nerve Nasociliary nerves
35. 35. In the orbit 1. Long root of ciliary ganglion 2. Long ciliary nerves 3. Posterior ethmoid nerve sensory no relay eyeball short ciliary nerves Two to three branches Iris & cornea Post ganglionic fibres From sup. Cervical ganglion. Posterior ethmoid canal Muc mem. Of post.ethmoidal cells Sphenoid sinus
36. 36. 4. Anterior ethmoid nerve Nasociliary continues anteriorly in medial of orbit Supplies mucous membrane of anterior ethmoid cells & frontal sinus. In the upper part of nasal cavity it divides in to two sets of anterior nasal branches External nasal branches Skin over the tip and ala of the nose Internal nasal branches Divide in the upper anterior part of the nasal cavity Medial/ septal Sensory to muc mem of that region Lateral Muc mem of ant ends sup & middle Nasal conchae Ant lat nasal wall
37. 37. Applied anatomy Ciliary ganglion It is topographically related to this nerve but functionally to oculomotor . Autonomic ganglia In case of injury to opthalmic nerve, there is loss of corneal blink reflex
38. 38. Maxillary nerve V2 The maxillary nerve is entirely sensory in function. Trigeminal ganglion Lateral wall of cavernous sinus Leaves skull through foramen rotundum Pterygo-palatine fossa Inferior orbital fissure Orbital cavity Infra orbital foramen
39. 39. Branches Branches given off in the middle cranial fossa Branches in the pterygopalatin e fossa Branches in the infraorbital groove and canal Terminal branches on the face
40. 40. Branches of the maxillary division Middle cranial fossa Middle meningeal nerve Pterygo-palatine fossa 1. Zygomatic nerve zygomaticotemporal zygomaticofacial 2. Pterygo-palatine nerves orbital nasal a. posterior superior lateral nasal branches b. nasopalatine palatine greater palatine middle palatine posterior palatine pharyngeal 3. Posterior superior alveolar GREATER PALATINE POSTERIO R PALATINE NASOPALATINE
41. 41. Infraorbital canal Middle superior alveolar Anterior superior alveolar Face Inferior palbebral External nasal Superior labial 1 PSA branches 2 Infra orbital n. 3 Maxillary nerve 4 Foramen rotundum 5 Greater palatine 6 Nasopalatine
42. 42. Applied anatomy Sphenopalatine ganglion It is topographically related to this nerve but functionally to facial nerve . It is the largest peripheral parasympathetic ganglion Autonomic ganglia In case of injury to opthalmic nerve, there is loss of sneeze reflex
43. 43. Mandibular division V3 Largest of the three divisions of the Vth nerve. Formed by union of large sensory & small motor bundle of fibers. Sensory fibers arise from semilunar ganglion. Motor fibers derived from motor cells located in the medulla oblongata.
44. 44. Course of the mandibular nerve Sensory root : Trigeminal ganglion Motor root : Medulla oblongata Exit cranium through foramen ovale Unite to form the main trunk After 2-3 mm divides to form Anterior and Posterior divisions
45. 45. Branche s Main trunk Anterior trunk Posterior trunk
46. 46. Branches from main trunk a) nervous spinosus: arises outside the skull passes into middle cranial fossa to supply dura & mastoid cells b) nerve to internal Pterygoid muscle: motor Internal pterygoid tensor veli palatini tensor tympani
47. 47. Branches from the anterior trunk Anterior trunk supplies (sensory & motor) skin & mucous membrane of the cheek, buccal gingivae &lower molars.It passes downward & forward where it divides: 1.Branch to external pterygoid muscle 2.Branch to masseter muscle 3.Branches to temporal muscles a. Anterior deep temporal nerve b. Posterior deep temporal nerve 4.Buccal (long buccal) nerve
48. 48. Branches from the posterior trunkmainly sensory with some motor components 1.Auriculotemporal 2.Lingual 3.Inferior alveolar
49. 49. Auriculotemporal nerve Arises by a medial & lateral root. The roots embrace the middle meningeal artery & unite just below the foramen spinosum Deep to Lateral pterygoid between sphenomandibular ligament & neck of condyle. Crosses zyg arch upwards and divides Branches: i. Parotid: sensory, secretory, vasomotor . ii. Articular: post TMJ iii. Auricular: skin of helix & tragus iv. Meatal : skin lining meatus & tympanic membrane v. Terminal: scalp over temporal region
50. 50. Communications of auricotemporal nerve: 1. Two roots of the nerve ,each root receives communicating fibers from the otic ganglion. These fibers are postganglionic parasympathetic secretory fibers that have come from the glossopharyngeal nerve by way of lesser superficial petrosal nerve. They control the secretion of the parotid gland. 2. Communicating branches of postganglionic sympathetic fibres vasomotor to parotid. 3. Communicating branches to facial purely sensory.
51. 51. Lingual nerve - Medial to Lateral Pterygoid muscle descends lies between medial pterygoid & ramus of mandible in pterygo mand space. - Contributes sensory fibers to the mucous membrane of the floor of mouth & gingiva on lingual surface of mandible. Also to bicuspids & 1st molars.
52. 52. Communications of the lingual nerve: As the lingual nerve passes medial to the lateral pterygoid muscle it is joined by corda tympani nerve, which conveys secretory fibres from the facial nerve. These parasympathetic fibers control the submandibular &
53. 53. Inferior alveolar nerve largest of the branches of the post div of mandibular nerve. Medial to ramus, in the pterygomandibular space, it enters the mand. Foramen It is distributed throughout the body of mandible In the canal apical fibres to dental pulp, also to periodontal membrane. At the mental foramen mental nerve, incisive nerve
54. 54. At mental foramen, div into 2 branches Mental nerve : leaves the mental foramen, supplies skin of the chin, lower lip & mm of lower lip. sensory Incisive nerve: fine incisive plexus to supply cuspids & incisors Before entering mandibular foramen, gives off mylohyoid branch Dwn & frwd in mylohyoid groove. Motor fibres: mylohyoid, ant belly of digastric. Sensory:mandibular incisors
55. 55. Autonomic ganglia associated with mandibular branch Submandibular ganglion: peripheral parasympathetic ganglion. Topographically related to lingual nerve, but functionally related to corda tympani branch of facial. Otic ganglion: peripheral parasympathetic ganglion. Topographically intimately related to mandibular nerve, but functionally to glossopharyngeal nerve.
56. 56. Applied anatomy Trigeminal neuralgia/Tic Douloureux characterised by extremely severe lancinating pain that occurs in paroxysms, limited to one or more branches of Trigeminal n. Etiology: Idiopathic Vascular compression Progressive degeneration Intra-cranial tumor Peripheral nerve injury
57. 57. Clinical features: - Older adults, Female predilection - Right side affected more - Intense shooting stabbing pain - Electric shock-like - Unilateral - Maxillary > Mandibular > Ophthalmic - Trigger zone
58. 58. Treatment of trigemial neuralgia Carbamazepine 100mg thrice daily, titrated over 1-5 weeks till remission. 1.Peripheral nerve- a. cryosurgery b. peripheral neurotomy 2.Gasserian ganglion- a.Thermocoagulation b. Glycerol injection 3.Brain stem- Microvascular decompression of nerve root
59. 59. Freys syndrome: damage to auriculotemporal nerve & subsequent reinnervation of sweat glands. C/F: Flushing & sweating on the invovled side of the face Treatment: severing the nerve Sensory distribution of trigeminal nerve explains why headache is a common symptom in invovlement of - the nose (common cold, boils ) - the PNS ( sinusitis ) -teeth & gums ( infections & inflamns ) -eyes ( refractive errors, glaucoma ) -meninges (meningitis )
60. 60. Posterior superior alveolar nerve block Complication s- Hematoma This is produced by inserting the needle far too posteriorly in to the pterygoid plexus of veins 1 maxillary nerve 2 posterior superior alveolar branches
61. 61. CRANIAL NERVES PART 2
62. 62. CONTENTS Introduction. Organization of Nervous System. Related Terminologies. Cranial Nerves. Detailed study of V. Trigeminal nerve VII. Facial nerve IX. Glossopharyngeal nerve X. Vagus nerve XII. Hypoglossal nerve References.
63. 63. FACIAL NERVE It is the seventh cranial nerve (VII) It is the nerve of the second branchial arch It is both motor and sensory
64. 64. Nuclei of the facial nerve Motor nucleus Superior salivatory nucleus Lacrimatory nucleus Nucleus of tractus solitarius
65. 65. Central connections Motor nucleus Upper part of face : Cortico-nuclear fibres from motor cortex of both sides. Lower part of face: Cortico-nuclear fibres from opposite cerebral hemisphere.
66. 66. Functional components Special visceral efferent muscles of 2nd branchial arch General visceral efferent secretomotor Special visceral afferent taste sensation from anterior 2/3rd of tongue and palate General somatic afferent part of skin of the ear
67. 67. Course The course of the facial nerve can be divided in to Intracranial Extracranial
68. 68. Intracranial course
69. 69. Structures in the left internal accoustic meatus
70. 70. Extracranial course Superficial to styloid process Pierces surface of parotid gland Runs forward Temporo-facial and Cervico-facial trunks Divides into 5
71. 71. Branches In the facial canal 1. Greater petrosal nerve 2. Nerve to stapedius 3. Chorda tympani At the stylomastoid foramen 1. Posterior Auricular 2. Digastric (posterior belly) 3. Stylohyoid Terminal branches within the parotid gland 1. Temporal 2. Zygomatic 3. Buccal 4. Marginal mandibular 5. Cervical Communicating branches with adjacent cranial and spinal nerves
72. 72. Applied anatomy Supra nuclear paralysis Infranuclear paralysis
73. 73. Infranuclear paralysis Lesion 1outside the stylomastoid foramen Lesion 2 in the facial canal and involving the corda tympani nerve Lesion 3 higher in the facial canal and involving the stapedius muscle Lesion 4 involving the geniculate ganglion Lesion 5 in the internal auditory meatus Lesion 6 at the emergence of facial nerve
74. 74. Bells Palsy Definition: Bells palsy is defined as an idiopathic paresis or paralysis of the facial nerve of sudden onset(unilateral lower motor neuron paralysis of sudden onset, not related to any other disease elsewhere in the body). Etiology Symptoms
75. 75. Treatment Physiotherapy Steroids - prednisolone 1mg/kg body wt for 10-14 days with a gradual tapering Proper care of the eye Antivirals Chronic sequeale Hyperkinesia Hypokinesia
76. 76. GLOSSOPHARYNGEAL NERVE IX Cranial nerve Mixed Nerve of third branchial arch Ganglia Detached part of inferior No branchesSuperior Larger Inferior
77. 77. Nuclei of the Glossopharyngeal nerve Nucleus ambiguus Inferior salivatory nucleus Nucleus of tractus solitarius
78. 78. Functional components
79. 79. SVE GVE AFFEREN T
80. 80. Course - Intracranial 3-4 rootlets Medulla oblongata Root trunk Presents 2 ganglia Jugular foramen
81. 81. Course - Extracranial Internal jugular vein and Internal carotid artery Internal and External carotid arteries Side of the pharynx Submandibular region Lingual Branches Tonsillar Branches
82. 82. Branches Tympanic Carotid Pharyngeal Muscular Tonsillar Lingual
83. 83. Applied Anatomy Glossopharyngeal neuralgia Rare Paroxysmal pain Trigger zone May be associated with vagal symptoms Etiology : Tumours and vascular abnormalities Treatment : Carbamazepine Surgical section of nerve Percutaneous radiofrequency thermocoagulation Microvascular decompression
84. 84. VAGUS NERVE X cranial nerve Extensive (vague) course 3 parts- Cervical Thoracic Abdominal Cervical part presents 2 ganglia Inferior Superior
85. 85. Nuclei of the vagus nerve Neucleus ambiguus Dorsal nucleus of vagus Nucleus of solitary tract Spinal nucleus of trigeminal nerve
86. 86. Functional components
87. 87. Course Medulla oblongata Jugular foramen Carotid Sheath Root of the neck Right/Left Vagus
88. 88. Branches JUGULAR FORAMEN Meningeal Auricular NECK Pharyngeal branches Superior laryngeal Branches to carotid body Cardiac branches Right recurrent laryngeal THORAX Cardiac Left recurrent laryngeal Pulmonary Oesophageal ABDOMEN Gastric Coelic Hepatic
89. 89. Applied Anatomy 1. Clinical testing 2. Paralysis of the vagus nerve 3. Irritation of the auricular branch of the vagus 4. Stimulation of the auricular branch 5. Irritation of the recurrent laryngeal nerve 6. Communication with facial nerve
90. 90. Hypoglossal Nerve XII cranial nerve Motor Supplies all muscles of the tongue, except palatoglossus muscle
91. 91. Nuclei & Functional components Hypoglossal nucleus: elongated nucleus Functional components: General somatic efferent
92. 92. 10- 15 rootlets through medulla oblongata Two bundles Pierce dura mater Lower part of the canal single nerve trunk Hypoglossal canal Between internal jugular vein and internal carotid artery It decends between internal jugular vein & internal carotid artery in front of the vagus deep to the parotid gland ,the styloid process, post. belly of diagastric,stylohyoid, and posterior auricular & occipital arteries Course
93. 93. At the lower border of post. Belly of diagastric it curves forwards, hooks round the lower sternomastoid branch Of occipital artery crosses IC & EC arteries & the loop of the lingual artery & enters submandibular region Rests on hyoglossus muscle Deep to mylohyiod muscle Pierces genioglossus Substance of the tongue
94. 94. Branches Meningeal Descendin g Thyrohyoid Muscular
95. 95. Applied Anatomy Clinical testing---by asking the patient to protrude his tongue. Lesion produces paralysis of the tongue of that side. Inranuclear lesion gradual atrophy of paralyzed half of the tongue. Supranuclear lesion paralysis without wasting.
96. 96. A clinicians complete knowledge of the anatomy of the cranial nerves and its applied aspect is necessary for providing treatment and preventing complications in routine clinical practice.
97. 97. References 1) Human anatomy BD Chaurasia. Vol 3, 3rd edition. 2) Grays anatomy 39th edition. 3) Handbook Of Local Anaesthesia, Malamed 5th edition. 4) Burkets Oral medicine-10th edition. 5) Lee Mc Gregors synopsis of surgical anatomy 12th edition. 6) Monheims local anesthesia & pain control in dental practice.7th edition. 7) Human physiology Chatterjee 10th edition. 8) Correlative neuroanatomy and functional neurology Chusid 16th edition. 9) Stedmans medical dictionary 21st edition. 10) Textbook of OMFS Neelima Malik 1st edition. 11) Textbook of human neuroanatomy Inderbir Sing 6th edition. 12) Cranial nerves functional anatomy Stanley Monkhouse. 13) Electronic media.