Department of Anatomy, Tokyo Dental College, Tokyo, Japan.
Department of Neurology, Wonkwang University School of Medicine and Hospital, Institute of Wonkwang Medical Science, 895, Muwang-ro, Iksan-si, Jeollabuk-do, 54538, Republic of Korea.
Surg Radiol Anat. 2020 Jul;42(7):761-770. doi: 10.1007/s00276-020-02443-5. Epub 2020 Feb 28.
A long tortuous course of the abducens nerve (ABN) crossing a highly curved siphon of the internal carotid artery is of interest to neurosurgeons for cavernous sinus surgery. Although a "straight" intracavernous carotid artery in fetuses can change into an adult-like siphon in infants, there is no information on when or how the unique course of ABN is established. Histological observations of 18 near-term fetuses (12 specimens of frontal sections and 6 specimens of sagittal sections) demonstrated the following: (I) the ABN consistently took a straight course crossing the lateral side of an almost straight intracavernous carotid artery; (II) the straight course was maintained when sympathetic nerves joined; (III) few parasellar veins of the developing cavernous sinus separated the ABN from the ophthalmic nerve; and (IV) immediately before the developing tendinous annulus for a common origin of extraocular recti, the ABN bent laterally to avoid a passage of the thick oculomotor nerve. Since the present observations strongly suggested morphologies at birth and in infants, major angulations of the ABN as well as the well-known course independent of the other nerves in the cavernous sinus seemed to be established during childhood. In the human body, the ABN might be a limited example showing a drastic postnatal change in course. Consequently, it might be important to know the unique course of ABN before performing endovascular interventions and skull base surgery for petroclival and cavernous sinus lesions without causing inadvertent neurovascular injuries to neonates or infants.
展神经（ABN）在走行中迂曲较长，跨越颈内动脉虹吸段，这一解剖结构对神经外科医生施行海绵窦手术有重要意义。尽管胎儿的颈内动脉在颅腔段是直的，但在婴儿期可变成类似成人的虹吸段，然而，ABN 独特走行的确立时间和方式尚不清楚。本研究对 18 例近足月胎儿（12 例额状切面标本和 6 例矢状切面标本）进行了组织学观察，结果发现：（I）ABN 始终走行于近乎直的海绵窦内颈内动脉的外侧，呈直线；（II）当交感神经加入后，直线走行得以维持；（III）发育中的海绵窦很少有颅腔旁静脉将 ABN 与动眼神经分开；（IV）在共同起源于眼外肌的腱膜环发育之前，ABN 向外侧弯曲，以避免粗大的动眼神经通过。由于本研究观察到的形态存在于出生时和婴儿期，因此 ABN 的大角度弯曲以及在海绵窦内不依赖于其他神经的已知走行似乎在儿童期就已确立。在人体中，ABN 可能是一个明显的出生后在走行上发生剧烈变化的局限例子。因此，在行涉及岩骨尖和海绵窦病变的血管内介入治疗和颅底手术时，了解 ABN 的独特走行对于避免对新生儿或婴儿造成意外的神经血管损伤可能非常重要。
