Lachman Nirusha, Acland Robert D, Rosse Cornelius
Department of Human Biology, Tecnikon Natal, Durban, South Africa.
Clin Anat. 2002 Jan;15(1):4-10. doi: 10.1002/ca.1084.
The accessory nerve is conventionally described as having a cranial and spinal root. According to standard descriptions the cranial root (or part) is formed by rootlets that emerge from the medulla between the olive and the inferior cerebellar peduncle. These rootlets are considered to join the spinal root, travel with it briefly, then separate within the jugular foramen to become part of the vagus nerve. In 15 fresh specimens we exposed the posterior cranial fossa with a coronal cut through the foramen magnum and explored the course of each posterior medullary rootlet (PMR) arising from within the retro-olivary groove. We chose the caudal end of the olive as the landmark for the caudal end of the medulla. In all specimens every PMR that did not contribute to the glossopharyngeal nerve joined the vagus nerve at the jugular foramen. The distance between the caudal limit of the olive and the origin of the most caudal PMR that contributed to the vagus nerve ranged from 1-21 mm (mean = 8.8 mm). All rootlets that joined the accessory nerve arose caudal to the olive. The distance from the caudal limit of the olive and the most rostral accessory rootlet ranged from 1-15 mm (mean = 5.4 mm). We were unable to demonstrate any connection between the accessory and vagus nerves within the jugular foramen. Our findings indicate that the accessory nerve has no cranial root; it consists only of the structure hitherto referred to as its spinal root.
副神经传统上被描述为有一个颅根和一个脊根。根据标准描述，颅根（或部分）由从延髓橄榄体和小脑下脚之间发出的根丝形成。这些根丝被认为与脊根相连，短暂地与之同行，然后在颈静脉孔内分开，成为迷走神经的一部分。在15个新鲜标本中，我们通过冠状切开枕骨大孔暴露后颅窝，探查从橄榄后沟内发出的每一根延髓后根丝（PMR）的走行。我们选择橄榄体的尾端作为延髓尾端的标志。在所有标本中，每一根不参与构成舌咽神经的PMR都在颈静脉孔处与迷走神经相连。橄榄体尾端与最尾侧参与构成迷走神经的PMR起始点之间的距离为1 - 21毫米（平均 = 8.8毫米）。所有与副神经相连的根丝都起源于橄榄体尾侧。橄榄体尾端与最头侧的副神经根丝之间的距离为1 - 15毫米（平均 = 5.4毫米）。我们未能证实颈静脉孔内副神经与迷走神经之间存在任何联系。我们的研究结果表明，副神经没有颅根；它仅由迄今被称为其脊根的结构组成。
