Question 978
{"accessible":false,"alternatives":[{"id":4902,"text":"CN V"},{"id":4903,"text":"CN VII"},{"id":4904,"text":"CN VIII"},{"id":4905,"text":"CN XI"}],"archived":false,"correctAlternativeId":4904,"explanation":"\u003cp\u003eThe\u0026nbsp;transition zone\u0026nbsp;of a nerve is a roughly 2 mm region where the myelin sheath changes from central to peripheral type.\u0026nbsp; This zone is susceptible to mechanical irritation and is implicated in neurovascular compression syndromes such as\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/trigeminal-neuralgia\"\u003etrigeminal neuralgia\u003c/a\u003e\u0026nbsp;(CN V),\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/hemifacial-spasm\"\u003ehemifacial spasm\u003c/a\u003e\u0026nbsp;(CN VII),\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/missing?article%5Btitle%5D=vestibular%C2%A0paroxysmia\"\u003evestibular\u0026nbsp;\u003c/a\u003e\u003ca href=\"https://radiopaedia.org/articles/missing?article%5Btitle%5D=vestibular%C2%A0paroxysmia\"\u003eparoxysmia\u003c/a\u003e\u0026nbsp;(CN VIII) and\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/glossopharyngeal-neuralgia\"\u003eglossopharyngeal neuralgia\u003c/a\u003e\u0026nbsp;(CN XI).\u0026nbsp;\u0026nbsp;\u003c/p\u003e\u003cp\u003eThe location of the transition zone relative to the\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/missing?article%5Btitle%5D=root+entry+zone\"\u003eroot entry zone\u003c/a\u003e\u0026nbsp;for a cranial nerve can be useful in understanding whether a contacting vessel is likely to cause neuralgia or not.\u0026nbsp; For CN V, VII and IX the transition zones are located very close to the root entry zone (within a few millimetres). CN VIII has a transition zone further along the nerve (around 10 mm).\u0026nbsp;\u003c/p\u003e","id":978,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/1983","nextQuestionPath":"/articles/hemifacial-spasm/questions/976","relatedArticles":[{"id":7174,"title":"Glossopharyngeal neuralgia","link":"/articles/glossopharyngeal-neuralgia?lang=gb"},{"id":33200,"title":"Trigeminal neuralgia","link":"/articles/trigeminal-neuralgia?lang=gb"},{"id":57135,"title":"Transition zone (nerve)","link":"/articles/transition-zone-nerve?lang=gb"}],"alsoUsedIn":[],"stem":"\u003cp\u003eWhich of these cranial nerves has its transition zone located the furthest away from its root entry zone?\u0026nbsp;\u003c/p\u003e","menuLinks":[{"text":"Report problem with question","url":"https://docs.google.com/forms/d/e/1FAIpQLSfO3soWYhOjJ7yErSysyCe5V4A1CqW7WK3rDA7MtAkecMGqNw/viewform?entry.1624461248\u0026entry.553583435=https://radiopaedia.org/questions/978"}],"attemptsPercentages":[{"alternativeId":"4903","percentage":19},{"alternativeId":"4905","percentage":17},{"alternativeId":"4904","percentage":38},{"alternativeId":"4902","percentage":26}],"promptToLogin":false,"questionManager":false,"articleId":"hemifacial-spasm"}