The cranial nerves

There are 12 pairs of cranial nerves that are individually named and numbered using Roman numerals. Only some cranial nerves are mixed in function, i.e. they carry both sensory and motor fibres; others are purely sensory or motor and some may also carry pre- or post-ganglionic parasympathetic fibres. They pass through foramina in the base of the skull and are the olfactory (through cribriform plate to the nasal cavity), optic (through the optic foramen to the eye), oculomotor (through the cavernous sinus and superior orbital fissure to supply the eye), trochlear (as per oculomotor), trigeminal (three main branches that pass through the superior orbital fissure, foramen rotundum and foramen ovale, respectively), abducens (as per oculomotor), facial (through stylomastoid foramen to supply muscles of facial expression), vestibulocochlear (through the internal acoustic canal to control balance and hearing), glossopharyngeal, vagus, accessory (all pass through the jugular foramen) and hypoglossal (through the hypoglossal canal to control movements of the tongue) nerves.

MORPHOMETRIC AND MORPHOLOGICAL STUDY ON FORAMEN OVALE

Background: Foramen ovalee is an important foramen of the middle cranial fossa. Foramen ovalee is situated in the greater wing of the sphenoid bone, posterior to the foramen rotundum and lateral to the lingula and posterior end of the carotid groove. Through the foramen ovale the mandibular nerve, accessory meningeal artery and lesser petrossal nerve are passing through it. The shape of foramen ovale is ovale in shape as compare to other foramina of the skull, its shape and size is quite variable. Meterials And Methods: A total 250 skulls were used for this study. The skulls were collected with I MBBS student from different medical colleges in south India. Skulls in poor conditions or skulls with partly damaged surroundings of the foramen ovalee were not considered. Maximum length and width of foramen ovalee was measured. Variation in right and left side and sex difference in length and width were calculated, the variations in shape also recorded. Results: The mean value of length of left foramen ovale is 8.5+1.32mm and right was 8.9+1.67mm. In female it was 8.7+1.67mmandmalewas 8.4+1.71mm. Themean value ofwidth of left foramen ovale is 3.7+1.03mmand right was 3.9+0.98mm. In female it was 3.8+0.92mm andmale was 3.7+1.02mm.The shape of foramen ovalewas ovale in 69% of skulls, almond in 29% of skulls and round was 2% of skulls. Conclusion: The present study conclude that there is signicant difference between sizes of right and left side foramen ovale and found that between male and female foramen ovale sizes also not shown any signicance difference. Foramen ovale has practical signicance to both neurosurgical and functional cranial neuroanatomy as it provides transcutaneous approaches to the skull base especially in cases of trigeminal neuralgia, as the Gasserion ganglion can be approached through it.

Spheno-Orbital Meningioma with Cavernous Sinus Extension

We present a case of a 37-year-old female, with progressive left eye proptosis and an extensive ipsilateral en plaque spheno-orbital meningioma, with diffuse involvement of the lateral wall of the cavernous sinus and the orbit.A cranio-orbital zygomatic approach was performed to reach all extension of the lesion. We made an extradural clinoidectomy and an extensive bone removal of the orbit, exposition of the superior and lateral walls of the cavernous sinus, unroofing of the optic canal, superior orbital fissure, foramen rotundum, and foramen ovale. We performed the peeling of the lateral wall of cavernous sinus with total removal and preservation of the cranial nerves anatomy and function.In this video, we illustrate the importance of the first time aggressive removal of such tumors. We also demonstrate the concept that secondary invasion of the cavernous sinus are suitable for removal with cranial nerve preservation.The link to the video can be found at https://youtu.be/GJmkqVa6jSs.

Study of the pterigidal canal (vidian canal) through images of cone beam computer tomography.

Objective: The aim of this study was to evaluate the pterygoid canal (PC) by Cone Beam Computed Tomography (CBCT), establishing its configuration and proximity with anatomical structures. Material and Methods: We evaluated 398 CBCT exams, all from a public University radiology clinic archive. Four parameters were evaluated: single or double PC, distance between PC and the inferior part of the sphenoid sinus (SS), ratio of PC and SS and the distance between the PC and the foramen rotundum. Results: It was observed that most of the PC of the sample presented simple morphology, the most frequent type of relationship between the PC and the SS on both sides was the close contact with the wall. Among the cases that there were some distances between the PC and the inferior wall of the SS, the mean of this distance did not exceed 3.20 mm, being the left side (3.03 mm) slightly closer than the right (3.20 mm). Finally, the distances between the PC and the corresponding Foramen Rotundum are presented with mean values of 5.87 mm for the right side and 6.31 mm for the left side. Conclusion: CBCT examination is of paramount importance for PC identification; once in the studied sample, the mean values found evidence the close relation between the PC and the SS.KeywordsCone beam computed tomography; Endonasal approach; Vidian canal.

Spontaneous cerebrospinal fluid leak via foramen rotundum in a non-obese male presented as pseudo-Chiari malformation type I: a case report and literature review

Spontaneous cerebrospinal fluid (sCSF) leak from the skull base has been previously reported, but there are few reports of sCSF leak from the foramen rotundum due to its rare occurrence. This case report describes a 15-year-old male patient that presented with left side watery rhinorrhoea that had been present since he was 4 years of age and a history of repeated bouts of meningitis of unknown cause. A discharge sample from the nose tested positive for beta-2 transferrin. Preoperative computed tomography (CT) revealed a fistula between the cerebellopontine angle and the left sphenoid sinus. There was also a pseudo-Chiari malformation type I with ectopia of the cerebellar tonsil. Endoscopic transnasal surgery identified a leak from the foramen rotundum that was repaired using autologous material and a contralateral pedicle nasoseptal flap. At 6 months after surgery, the patient reported no recurrence of the CSF leakage. Postoperative CT imaging revealed that the cerebellar tonsil was back in the normal position, indicating that the preoperative Chiari malformation was possibly due to decreased CSF volume. This current case shows that a rare case of sCSF leak from the foramen rotundum can be effectively repaired using the endoscopic transnasal approach.