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  Indian J Med Microbiol
 

Figure 3: Intradural exposure of clivus and foramen magnum area. (a) Nasal, sphenoid, and clival stages of dissection have been completed. Bone from posterior clinoid to foramen magnum and anterior arch of C1 and dens has been removed exposing clival dura and transverse ligament. Petrous apex has also been drilled exposing the laceral segment of internal carotid artery. Some parts of lateral dura have been opened exposing cranial nerves. Paraclival internal carotid artery is seen on both sides. Vidian nerve is visible on both sides extending from inferolateral aspect of laceral segment of internal carotid artery to sphenopalatine ganglion. Both side eustachian tubes are visible in the inferior part of exposure. (b) Clival dura showing VI nerve passing into cavernous sinus on both sides. On the left side, dorsal clival artery branch of cavernous internal carotid artery can be seen extending along clival dura and giving blood supply to VI nerve. (c) Clival dura is opened leaving behind the layer of arachnoid. Vertebrobasilar junction is visible with the origin of anterior spinal artery. Anterior inferior cerebellar artery is seen arising from basilar artery and passing toward internal acoustic meatus. Cranial nerves from V to XII can be seen arising from brainstem. (d) Close-up view of the origin of cranial nerves. Both VI nerves have medial origin from pontomedullary junction with more angular inclining course. V nerve has more lateral origin and course. VII and VIII nerves can be seen passing into internal acoustic meatus with the loop of anterior inferior cerebellar artery. (e) Close-up view of cervicomedullary junction showing intradural entry of vertebral artery and origin of anterior spinal artery. Rootlets of XII nerve can be seen arising in relation to vertebral artery. Ventral rootlets of the first cervical nerve can be seen arising from the upper cervical cord just in front of dentate ligament. (f) Dissection of jugular foramen and hypoglossal canal. In the upper part, internal acoustic meatus is visible with anterior inferior cerebellar artery. Jugular foramen is opened and venous injection is removed showing IX nerve passing superiorly in a separate subcanal. X and XI cranial nerves can be seen traveling together just below IX nerve. XII nerve can be seen extending from brainstem through hypoglossal canal. AICA, anterior inferior cerebellar artery; ASA, anterior spinal artery; BA, basilar artery; FL, foramen lacerum; VA, vertebral artery; VN, vidian nerve

Figure 3: Intradural exposure of clivus and foramen magnum area. (a) Nasal, sphenoid, and clival stages of dissection have been completed. Bone from posterior clinoid to foramen magnum and anterior arch of C1 and dens has been removed exposing clival dura and transverse ligament. Petrous apex has also been drilled exposing the laceral segment of internal carotid artery. Some parts of lateral dura have been opened exposing cranial nerves. Paraclival internal carotid artery is seen on both sides. Vidian nerve is visible on both sides extending from inferolateral aspect of laceral segment of internal carotid artery to sphenopalatine ganglion. Both side eustachian tubes are visible in the inferior part of exposure. (b) Clival dura showing VI nerve passing into cavernous sinus on both sides. On the left side, dorsal clival artery branch of cavernous internal carotid artery can be seen extending along clival dura and giving blood supply to VI nerve. (c) Clival dura is opened leaving behind the layer of arachnoid. Vertebrobasilar junction is visible with the origin of anterior spinal artery. Anterior inferior cerebellar artery is seen arising from basilar artery and passing toward internal acoustic meatus. Cranial nerves from V to XII can be seen arising from brainstem. (d) Close-up view of the origin of cranial nerves. Both VI nerves have medial origin from pontomedullary junction with more angular inclining course. V nerve has more lateral origin and course. VII and VIII nerves can be seen passing into internal acoustic meatus with the loop of anterior inferior cerebellar artery. (e) Close-up view of cervicomedullary junction showing intradural entry of vertebral artery and origin of anterior spinal artery. Rootlets of XII nerve can be seen arising in relation to vertebral artery. Ventral rootlets of the first cervical nerve can be seen arising from the upper cervical cord just in front of dentate ligament. (f) Dissection of jugular foramen and hypoglossal canal. In the upper part, internal acoustic meatus is visible with anterior inferior cerebellar artery. Jugular foramen is opened and venous injection is removed showing IX nerve passing superiorly in a separate subcanal. X and XI cranial nerves can be seen traveling together just below IX nerve. XII nerve can be seen extending from brainstem through hypoglossal canal. AICA, anterior inferior cerebellar artery; ASA, anterior spinal artery; BA, basilar artery; FL, foramen lacerum; VA, vertebral artery; VN, vidian nerve