Division of Otorhinolaryngology, Sendai Municipal Hospital, Sendai, Japan.
J Anat. 2012 Apr;220(4):384-95. doi: 10.1111/j.1469-7580.2012.01478.x. Epub 2012 Feb 21.
In adults, the lateral pterygoid muscle (LPM) is usually divided into the upper and lower heads, between which the buccal nerve passes. Using sagittal or horizontal sections of 14 fetuses and seven embryos (five specimens at approximately 20-25 weeks; five at 14-16 weeks; four at 8 weeks; seven at 6-7 weeks), we examined the topographical relationship between the LPM and the buccal nerve. In large fetuses later than 15 weeks, the upper head of the LPM was clearly discriminated from the lower head. However, the upper head was much smaller than the lower head in the smaller fetuses. Thus, in the latter, the upper head was better described as an 'anterior slip' extending from the lower head or the major muscle mass to the anterior side of the buccal nerve. The postero-anterior nerve course seemed to be determined by a branch to the temporalis muscle (i.e. the anterior deep temporal nerve). At 8 weeks, the buccal nerve passed through the roof of the small, fan-like LPM. At 6-7 weeks, the LPM anlage was embedded between the temporobuccal nerve trunk and the inferior alveolar nerve. Therefore, parts of the LPM were likely to 'leak' out of slits between the origins of the mandibular nerve branches at 7-8 weeks, and seemed to grow in size during weeks 14-20 and extend anterosuperiorly along the infratemporal surface of the prominently developing greater wing of the sphenoid bone. Consequently, the topographical relationship between the LPM and the buccal nerve appeared to 'change' during fetal development due to delayed development of the upper head.
在成年人中，翼外肌（LPM）通常分为上下两部分，其间有颊神经通过。我们使用 14 个胎儿和 7 个胚胎的矢状或水平切片（5 个标本约为 20-25 周；5 个标本约为 14-16 周；4 个标本约为 8 周；7 个标本约为 6-7 周），检查了 LPM 与颊神经之间的局部解剖关系。在大于 15 周的较大胎儿中，LPM 的上部分明显与下部分区分开来。然而，在较小的胎儿中，上部分比下部分小得多。因此，在后一种情况下，上部分最好被描述为从前部延伸到颊神经前侧的下部或主要肌肉群的“前滑”。后前神经的行程似乎由颞肌分支（即前深颞神经）决定。在 8 周时，颊神经穿过小的扇形 LPM 的顶部。在 6-7 周时，LPM 原基嵌入颞颌神经干和下牙槽神经之间。因此，LPM 的部分可能在 7-8 周时从下颌神经分支的起点之间的裂隙“漏出”，并且在 14-20 周期间似乎增大，并沿蝶骨大翼的突出颞下表面向前上延伸。因此，由于上部分发育延迟，LPM 与颊神经之间的局部解剖关系在胎儿发育过程中似乎发生了“变化”。
