Summary
This anatomic study describes the course and intracranial relations of the hypoglossal n. in 32 cadavers. The rootlets of the nerve emerged as a fan-shaped distribution (23.44%) or in two bundles (76.56%) and converged towards the hypoglossal canal in the subarachnoid space before piercing the dura mater. In 76.57% of cases the rootlets pierced the dura mater in two separate apertures, less commonly through the same aperture (21.87%), and in rare cases through three individual apertures, as in one of our cases. The distance between the two apertures varied from 0.6 mm to 8.7 mm. Commonly, the two bundles converged together and left the skull through one foramen in the skull. However, in some cases (28.12%), the hypoglossal canal was divided in two by a small bony spicule. In 23.45% of cases the initial course of the posterior inferior cerebellar a. (PICA) passed between the two bundles of the hypoglossal n. before ascending towards the lateral border of the fourth ventricle.
Résumé
Cette étude anatomique décrit le trajet et les rapports intra-crâniens du n. hypoglosse chez 32 cadavres. Les racines nerveuses émergeaient selon une disposition en éventail (23,44 %) ou en deux fascicules (76,56 %) et convergeaient vers le canal de l'hypoglosse dans l'espace sub-arachnoïdien avant de traverser la dure-mère. Dans 76,57 % des cas, les racines traversaient la dure-mère par deux ouvertures séparées, moins souvent par le même orifice (21,87 %) et dans de rares cas par trois ouvertures séparées (1 cas). La distance séparant les deux ouvertures variait de 0,6 à 8,7 mm. Habituellement, les deux fascicules convergeaient l'un vers l'autre et quittaient le crâne par un seul foramen osseux. Cependant, dans quelques cas (28,12 %), le canal de l'hypoglosse était divisé en deux par un petit spicule osseux. Dans 23,45 % des cas, le trajet initial de l'a. cérébelleuse postérieure et inférieure (PICA) passait entre les deux fascicules du n. hypoglosse avant de monter vers le bord latéral du quatrième ventricule.
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Bhuller, A., Sañudo, J.R., Choi, D. et al. Intracranial course and relations of the hypoglossal nerve. Surg Radiol Anat 20, 109–112 (1998). https://doi.org/10.1007/BF01628913
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DOI: https://doi.org/10.1007/BF01628913