Macchi V, Porzionato A, Parenti A, De Caro R
Department of Human Anatomy and Physiology, Section of Anatomy, University of Padua, Via A Gabelli 65, 35121 Padua, Italy.
Surg Radiol Anat. 2004 Feb;26(1):60-5. doi: 10.1007/s00276-003-0190-2. Epub 2003 Dec 5.
The course of the posterior inferior cerebellar artery (PICA) was analyzed with reference to its origin and relationships with the medullary and cerebellar surfaces and the adjacent cranial nerves in 40 brains after the injection with acrylic resins of the vertebrobasilar system. In 42.5% of instances, the PICA originated from the lateral medullary segment of the vertebral artery (VA), in 32.5% from its premedullary segment, in 22.5% from the basilar artery (BA), and in 2.5% it was absent. With reference to the level of origin, three patterns of course for the lateral medullary segment of the PICA can be outlined. (1) When it arises from the lateral medullary segment of the VA, it passes below the hypoglossal nerve, and the lateral medullary segment may form a loop with an anterosuperior convexity towards the pontomedullary sulcus (41%), or it may follow a rectilinear course (41%). It passes at the level of the accessory nerve. The tonsillomedullary (TM) segment shows a caudal loop and the telovelotonsillary (TVT) has a cranial loop. (2) When the PICA arises from the BA, it passes above the hypoglossal nerve. The lateral medullary segment forms a loop with lateral convexity (78%) and passes above or through the glossopharyngeal nerve, frequently showing a recurrent course among the roots of the IX, X, or XI cranial nerve. The TM and the TVT segments do not have loops. (3) When the PICA arises from the premedullary segment of the VA, it passes above, below, or through the rootlets of the hypoglossal nerve. In the lateral medullary segment, it follows a rectilinear course (54%) and passes the plane formed by the IX, X, and XI cranial nerves at an intermediate level with respect to the other two patterns. The TM and the TVT segments show caudal and cranial loops. The different origins and courses of the PICA derive from the selection of different branches of the primitive vertebrobasilar plexus during the development of the cerebellum. The existence of an embryologic correlation between the course of the PICA and its level of origin may be useful in the evaluation of its angiographic anatomy.
在对40例经椎动脉-基底动脉系统注入丙烯酸树脂的脑标本进行研究后，分析了小脑后下动脉（PICA）的走行，包括其起源以及与延髓表面、小脑表面和相邻脑神经的关系。在42.5%的情况下，PICA起源于椎动脉（VA）的延髓外侧段，32.5%起源于其延髓前段，22.5%起源于基底动脉（BA），2.5%的情况下该动脉缺如。根据起源水平，可概述PICA延髓外侧段的三种走行模式。（1）当它起源于VA的延髓外侧段时，它走行于舌下神经下方，延髓外侧段可能形成一个向前上凸向脑桥延髓沟的袢（41%），或者它可能走直线（41%）。它在副神经水平走行。扁桃体延髓段（TM）呈尾侧袢，小脑扁桃体静脉段（TVT）有头侧袢。（2）当PICA起源于BA时，它走行于舌下神经上方。延髓外侧段形成一个向外侧凸的袢（78%），并走行于舌咽神经上方或穿过舌咽神经，常在第IX、X或XI对脑神经的根之间呈折返走行。TM段和TVT段没有袢。（3）当PICA起源于VA的延髓前段时，它走行于舌下神经根上方、下方或穿过舌下神经根。在延髓外侧段，它走直线（54%），并在另外两种模式的中间水平穿过由第IX、X和XI对脑神经形成的平面。TM段和TVT段显示尾侧和头侧袢。PICA不同的起源和走行源于小脑发育过程中原始椎动脉-基底动脉丛不同分支的选择。PICA走行与其起源水平之间存在胚胎学关联，这在评估其血管造影解剖结构时可能有用。
