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. 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. 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. 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. 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. 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. 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. 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. 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.
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. 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. Sensory and motor root of the trigeminal nerve The two
roots then enter the middle cranial fossa.
15. Superior view of the middle cranial fossa showing some of
its contents
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
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. Nuclei of the trigeminal nerve Sensory nuclei Mesencephalic
Primary sensory Spinal Motor nucleus
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. 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. Spinal (bulbospinal) nucleus: Caudal to the sensory
nucleus. Forms ventral trigeminothalamic tract. Convey pain &
temp from the entire Trigeminal area.
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. 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. 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. Special viceral efferent: fibers innervate the muscles of
mastication, the tensor tympani and the tenor veli palatini
muscles, anterior belly of digastric.
27. Divisions of the trigeminal nerve Opthalmic V1 Maxillary V2
Mandibular V3
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. Branche s Lacrimal Frontal Nasocilliary
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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Branche s Main trunk Anterior trunk Posterior trunk
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. 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. Branches from the posterior trunkmainly sensory with some
motor components 1.Auriculotemporal 2.Lingual 3.Inferior
alveolar
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. 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. 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. 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. 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. 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. 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. 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. Clinical features: - Older adults, Female predilection -
Right side affected more - Intense shooting stabbing pain -
Electric shock-like - Unilateral - Maxillary > Mandibular >
Ophthalmic - Trigger zone
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. 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. 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. CRANIAL NERVES PART 2
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. 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. Nuclei of the facial nerve Motor nucleus Superior
salivatory nucleus Lacrimatory nucleus Nucleus of tractus
solitarius
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. 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. Course The course of the facial nerve can be divided in to
Intracranial Extracranial
68. Intracranial course
69. Structures in the left internal accoustic meatus
70. Extracranial course Superficial to styloid process Pierces
surface of parotid gland Runs forward Temporo-facial and
Cervico-facial trunks Divides into 5
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. Applied anatomy Supra nuclear paralysis Infranuclear
paralysis
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. 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. 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. GLOSSOPHARYNGEAL NERVE IX Cranial nerve Mixed Nerve of
third branchial arch Ganglia Detached part of inferior No
branchesSuperior Larger Inferior
77. Nuclei of the Glossopharyngeal nerve Nucleus ambiguus
Inferior salivatory nucleus Nucleus of tractus solitarius
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
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. VAGUS NERVE X cranial nerve Extensive (vague) course 3
parts- Cervical Thoracic Abdominal Cervical part presents 2 ganglia
Inferior Superior
85. Nuclei of the vagus nerve Neucleus ambiguus Dorsal nucleus
of vagus Nucleus of solitary tract Spinal nucleus of trigeminal
nerve
86. Functional components
87. Course Medulla oblongata Jugular foramen Carotid Sheath
Root of the neck Right/Left Vagus
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. 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. Hypoglossal Nerve XII cranial nerve Motor Supplies all
muscles of the tongue, except palatoglossus muscle
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. 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. Branches Meningeal Descendin g Thyrohyoid Muscular
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. 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. 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.