 For the next 15 minutes to be talking about hemorrhoin anatomy of the cranial nerves This is a simplified overview showing the cranial nerves from superior to inferior except the first and the twelfth cranial nerves The second cranial nerve as you see Arrises from top of the mid-brain Third cranial nerve, the oculomotor, arises at the junction of the mid-brain and the pons The fourth and the fifth cranial nerves arise from the pons itself The sixth cranial nerve arises from the pontobedillary junction While the seventh and eighth cranial nerves arise from the lateral aspect of the mid-brain Ninth, tenth and twelfth cranial nerves arise close to each other from the mid-brain while the eleventh cranial nerve arises most inferiorly from the cervical spinal cord Students have been finding ingenious ways for remembering the cranial nerves This is one of the ways This is one more So a special point to remember is that the first and the second cranial nerves are not lined by swan cells Therefore, if you see a mass lesion along the first or the second cranial nerves It is not just swanoma. Most commonly it would be a glioma While reporting cranial nerves, it is preferable to use numerical instead of the more common Roman style of numbering to avoid confusion So we need isotropic sequences to visualize the cranial nerves Isotropic sequences can be reconstructed in any plane regardless of the plane of acquisition Cis and phia start intuitive sequences while Vyban, Bravo, whatever, middle sequences Both of these can be obtained free as well as post-con traps Of these cis in Siemens and Fiesta and G are the most important Because of high signal to noise ratio, less CSF law artifacts And mixed T1 and T2 weighting which enables post contrast imaging also Even though it is a T2 weighted sequence Of these two sequences, cis is the one which is more commonly known amongst our neurosurgery colleagues because of the sheer popularity of Siemens machines Cranial nerve segments is an important concept to understand These segments are based on the structures through which each cranial nerve passes Hence each segment has different imaging plane and each segment is best seen on a different sequence The pathologies affecting each segment can also be different based on the structures adjacent to that segment Knowledge of the segments of the cranial nerves helps in exact localization of the pathology And also in surgical planning This is a very important diagram It shows the simplified concept of segmental anatomy of the cranial nerves And it can be applied to all the cranial nerves Going from left to right, assuming outgoing cranial nerves Even though efferent as well as different fibers are present in the cranial nerves The first segment is nuclear segment That is the nucleus from which the cranial nerve arises Second is the part of the cranial nerve which courses through the brain parenchyma itself Both of these segments are not directly visualized on imaging But their location can be determined based on certain landmarks Next comes the cisternal segment This segment is surrounded by CSF Hence it is clearly visualized on T2 weighted images including CIS and CSR Next is the Dural Cave segment Which is the part of the cranial nerve which invigorates into the dura This is also surrounded by CSF and is also well seen on T2 weighted images Next is the interdural segment In which the cranial nerve is about to leave the dura It lies between the meningeal and the perostial surface of the dura matter Most familiar example of this will be the cavernous sinus In which the third, fourth, sixth and branches of the fifth cranial nerve are coursing This segment is surrounded by venous blood Hence it is not easily seen on routine images But it can be well visualized on post-contrast imaging Next is the foraminal segment And as you can guess it is the part which courses through the individual foramins And this segment is surrounded by the bones And apart from the facial nerve for all the other cranial nerves It is a very short segment Then comes the extra foraminal segment Which can be a very long segment Especially in the case of the oculomotor nerve, facial nerve and the vegas nerve It is surrounded by fat, muscles or bones This segment is also well seen on different kinds of sequences depending on the location Now coming to the individual anatomy of the cranial nerves Overview of the first cranial nerve that is the olfactory nerve It consists of the olfactory bulb and the olfactory tract And it lies along the basic frontal region This is a coronal CT scan in the bone window It shows the CSF segment of the olfactory nerve The bony landmark for this is the crista gel Which lies between the right and the left olfactory nerves The groove in which the nerve lies is called the olfactory groove The depth of the groove is important knowledge for the ENT surgeon So there is in this area And there is a separate classification for the depth of this groove Which is known as the keros classification This is the same area on coronal t-truvated imaging Which shows the olfactory bulb surrounded by CSF As well as the basic frontal region Now here two gyri are seen One is the gyrus rectus medial And the olfactory gyrus latrine The crista gel lies between the two nerves This is the overview of the second cranial nerve That is the optic nerve It arises from the optic radiation Or rather it ends in the optic radiation Which represents the parenchymal fascicular segment of this nerve Also along the course of the nerve are the nuclear segments Represented by the medial and lateral geniculate bodies The optic tract, optic chiasm and part of the optic nerve Is in the cisternal segment While the rest of the optic nerve goes through the other segments As we will see ahead This is the axion fadsat t-truvated image Which shows the cisternal interdural foraminal Extra foraminal segments of the optic nerve The optic tract chiasm and the proximal optic nerves Are the cisternal segments The part which just enters the dura But not yet reach the foraminal is the interdural segment The part which enters the optic foraminal is the foraminal segment And the extra foraminal segment is more commonly known as The interorbital segment of the optic nerve This is the cisternal segment of the optic nerve At the level of the cavernous sinus The inferior relations of the optic nerve are seen here Which is mainly the cavernous segment of the internal carotid artery The relationships of the extra foraminal That is the interorbital segment of the optic nerve are seen In this coronal t-vitid image of the right orbit It is normally surrounded by the retrovalver fat Without any fat standing in this area The third, fourth and sixth cranial nerves Supply the extrapular muscles All the muscles are supplied by the third cranial nerve Except for the superior oblique supplied by the fourth And the lateral rectus which is supplied by the sixth cranial nerve This schematic shows the nuclear and the parankanel As well as the cisternal segments of these nerves This is the overview of the keromotor nerve It shows the short nuclear and the parankanel segment Then the fairly long cisternal segment The interdural segment, canalicular segment And the extra foraminal segment This axial T2 and sagittal image shows the Nuclear parankanel and cisternal segments of the ocular motor nerve The cisternal segment of the ocular motor nerve Especially has important relations Which is seen in this coronal t-vitid image Superiorly the posterior cerebral And inferiorly the superior cerebral And closed radiation So aneurysm of these arteries Can affect the ocular motor nerve This is the interdural Or the cavernous segment of the ocular motor nerve Which lies at the superior and the lateral corner Of the cavernous sinus The CSF around this ocular motor nerve Which is called the ocular motor system Can be enlarged behind intracranial hypertension To the fourth trochlear cranial nerve This is one of the thinnest cranial nerves And it's very hard to see unless you have taken 0.5 And 6 or 3 years of sequences It arises from the dorsal aspect of the mid-brain Unlike the other cranial nerves Which is an overview of the fifth cranial nerve Which arises from its nucleus in the pons It has a glycerin ganglion Which lies in the macroscape And it has three branches Hence trigeminal First is the ophthalmic branch Which courses through the superior orbital fissures Second is the maxillary branch Which courses through the foramen rotandum And third is the mind-billard branch Which courses through the foramen ovale This is the coronal image SPAC Showing the system and segment of the fifth cranial nerve Coming anteriorly this is the dural cave segment That is the macroscape segment of the fifth cranial nerve Which is seen immediately inferior to the cavernous sinus And immediately superior to the foramen ovale These represent the locations of the foramen nerve Segments of the fifth cranial nerve That is the foramen rotandum for the maxillary division Which communicates to the teridoperatin fossa And the foramen ovale for the manipular division Which communicates with the infratemporal fossa This is the nuclear and parankinema segments Of the sixth and seventh cranial nerve So there is a paradox here At the level of the fourth ventricle We see a bulging Along the anterior margin of the fourth ventricle Which is called the facial colliculus But infrat The nucleus for the sixth cranial nerve Lies underneath the facial colliculus Instead of the facial nucleus This is an overview of the abductions now This is the nuclear and the Parankinema segment The short cisternal segment The cavernous sinus Or the intradural segment And the extra foramen or the interorbital segment Now the cisternal segment of the sixth cranial nerve Is unique because it ascends Instead of descending through the CSF Which is well seen in the societal image This is also a thing when Will not be seen unless you have taken At least 0.5 mm thin Cisfor fiesta in place In the actual images It is seen immediately After the pons ends And just at the beginning of the medulla Anterior inferior cerebral artery Is seen across its location This demonstrates the cisternal As well as the intradural segments Of the sixth cranial nerve The ascending part surrounded by CSF Is the cisternal segment While the intradural segment Is not well seen on this plane image But it can be seen very well On a post contrast image This is the overview of the seventh cranial nerve Now there are different ways of classifying The segments of the seventh cranial nerve On the left is one of the ways On the right is a simple, simpler way The cisternal segment Is also known as the intracranial segment Canalicular segment is also known as the Segment in the intranural trig canal The labyrinthine and the tympanic segments Represent the foraminal segments They are also known as the intratemporal segment While the descending and the parotid segments Are also known as the extratemporal segments And these represent the extra foraminal segments On the seventh cranial nerve So one should be familiar with all these terms In order to discuss the findings with the EAT segment This is the axial pittress bone CD Showing the dural cave and the foraminal segments Of the seventh cranial nerve The part of the seventh cranial nerve In the intranural trig canal Is actually not the foraminal segment But the dural cave segment Because it is surrounded by a CSF The foraminal segment consists Of the labyrinthine part And the tympanic part Between which lies the turn of the facial nerve Which is known as the Geniculate segment This is again the dural cave of the intranural Pillar segment of the facial nerve Seen on coronal images There is mild hyperenagement of the left-sided facial nerve This is the same patient in axial Now this is an important section Which shows the societal view Of the intranural segment And it shows two nerves Seventh as well as the eighth nerve So four structures are Four diamond structures are seen in this image On the left is anterior And the right is posterior The easy way to remember is that Posteriorly is The vestibular nerve which is the eighth nerve And anteriorly are the seventh and the That is the facial and the cochlear nerve So an easy mnemonic to remember This is seven up and coca-cola So seven is up, that is Facial nerve is superiorly And coca-cola is below Cochlear is below The nine, ten, ten, eleven, thirteen Nerves are grouped together Because of the common origin And they force very close to each other And ultimately force together Through the jugular forearm By scrolling these nerves It is virtually They are indistinguishable From each other And they follow each other Very close succession The nine, ten, ten cranial nerves Both of them will force through the Gloss of arranging forearm And like the ninth and the Ten cranial nerves The twelve cranial nerves Forces fairly inferiorly And as a separate forearm Which is known as the Hypoclasm canal So here we can see In axial city the hypoclasm canal Which as well as in the MRI also we can see it It lies much below The expected location of the Gloss of arranging forearm All of these relationships can be Better seen on the Email stacks which will come Next This is the sedentary T2 stack These are the semicircular canal Cochlear Here are the four structures Which we have seen before In the internal retic canal Seven of that is the Facial nerve anteriorly And superiorly And Copacola That is the cochlea Inferiorly and superior Inferior vestibular nerve posteriorly This is the axial cyst Here is the stack Which most of us are used to Seek And it will show majority Of the cranial nerves So going from Up to bottom This is the Cystral segment of the Third cranial nerve And this subtle line Is the Fourth cranial nerve So this is the cranial and the Michael's cave segment of the Fifth cranial nerve These 10 lines seen at the Quantum illusion will be the Sixth cranial nerve Immediately below the Sixth cranial nerve would be The seventh and the Eighth cranial nerves And the internal retic canal An acoustic sonoma is seen On the right side The seventh and the Eighth cranial nerves There is a landmark Which you can see on either side Which is known as the Cerebrular floculus And it lies between The Seventh and the Eighth And The Ninth and the Ten cranial nerves Inferiorly So in summary Knowing cranial and anatomies Vital in MRI reporting Cranial nerves can be Divided into segments Based on the structures Through which we are passing Each segment has different Amazing and pathologies And segmentary anatomies Helps in locating pathology And planning surgery Sys and fears And the corners Tone of cranial nerve Amazing And this talk is based on The excellent article by Blitz, A.M. Hendoff Thank you very much