Bagnall K M, Harris P F, Jones P R
J Anat. 1977 Jul;123(Pt 3):777-82.
The present study has shown that the secondary curvature in the cervical spine of the human fetus develops at a much earlier age than has been thought. It may, in fact, develop soon after the embryo first acquires a neck and begins to uncurl. The early appearance of this curvature may be related to the early development of function in the muscles responsible for head extension, this movement being a basic component of the primitive "gasp" reflex. It is further suggested that, although the embryo develops in flexion, the traditional assumption that such flexion is a consequence of fetal musculoskeletal development must be questioned, and the expression "normal fetal flexed position" is probably misleading, since it does not take into account the wide range of movements of which the fetus is capable.
本研究表明，人类胎儿颈椎的继发性弯曲比之前认为的出现得要早得多。事实上，它可能在胚胎首次长出颈部并开始伸直后不久就开始发育了。这种弯曲的早期出现可能与负责头部伸展的肌肉功能的早期发育有关，而这种运动是原始“喘息”反射的基本组成部分。进一步表明，尽管胚胎在屈曲状态下发育，但传统观点认为这种屈曲是胎儿肌肉骨骼发育的结果，这一观点必须受到质疑，而且“正常胎儿屈曲姿势”这种表述可能会产生误导，因为它没有考虑到胎儿能够进行的广泛运动范围。
