Kocabiyik Necdet, Tatar Ilkan, Yalcin Bulent, Ozan Hasan
Department of Anatomy, Gulhane Military Medical Academy, Ankara, Turkey.
Clin Anat. 2008 Oct;21(7):691-5. doi: 10.1002/ca.20698.
The pudendal nerve is a considerably large branch of the sacral plexus. There are many articles in the literature concerning the pudendal nerve in adults, but as far as we know, there is none on the branching pattern and variations in pudendal nerve anatomy in fetus. This study investigates the pudendal nerve trunking with respect to the piriformis muscle in 25 formalin-fixed fetuses (50 sides of pelves, 15 females, 10 males), ranging from 20 to 37 weeks of gestation. We investigate pudendal nerve trunking in four types: Type I-a is defined as single-trunk with the inferior rectal nerve branching proximal to the dorsal nerve of penis/clitoris (38%), Type I-b is also single-trunk with the dorsal nerve of penis/clitoris branching proximal to the inferior rectal nerve (24%), Type II is double-trunk with medial trunk as an inferior rectal nerve (34%), and Type III is triple-trunk (4%). We measured the average diameter of the main trunk of pudendal nerve in Type I-a and I-b groups to be 0.98 +/- 0.33 mm. We also measured the average length of the pudendal nerve trunks before the dorsal nerve of penis/clitoris branch to be 7.35 +/- 3.50 mm. There was no significant statistical difference in the average length, diameter, number of trunks, and pudendal nerve variations between male and female and also right and left sides of the pelves. This first and detailed fetal study of pudendal nerve trunking with respect to the piriformis muscle would be useful for educational anatomy dissections and anatomical landmark definitions for relevant clinical procedures.
阴部神经是骶丛的一个相当大的分支。文献中有许多关于成人阴部神经的文章，但据我们所知，尚无关于胎儿阴部神经解剖分支模式和变异的文章。本研究调查了25例福尔马林固定胎儿（50侧骨盆，15例女性，10例男性）中，与梨状肌相关的阴部神经主干情况，胎龄为20至37周。我们将阴部神经主干分为四种类型：I - a型定义为单干型，直肠下神经在阴茎/阴蒂背神经近端分支（38%）；I - b型也是单干型，阴茎/阴蒂背神经在直肠下神经近端分支（24%）；II型为双干型，内侧干为直肠下神经（34%）；III型为三干型（4%）。我们测量I - a型和I - b型组阴部神经主干的平均直径为0.98±0.33毫米。我们还测量了阴茎/阴蒂背神经分支前阴部神经主干的平均长度为7.35±3.50毫米。在平均长度、直径、主干数量以及阴部神经变异方面，男女之间以及骨盆左右两侧之间均无显著统计学差异。这项关于与梨状肌相关的阴部神经主干的首次详细胎儿研究，将有助于教育解剖学 dissection以及相关临床操作的解剖学标志定义。
