Centre de Recherche en Paléontologie-Paris (CR2P), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, Paris, France.
Mécanismes Adaptatifs et Evolution (Mecadev), Muséum National d'Histoire Naturelle, CNRS, Bâtiment d'Anatomie Comparée, Paris, France.
J Morphol. 2023 Jun;284(6):e21595. doi: 10.1002/jmor.21595.
In contrast to the well-studied articulated vertebrate jaws, the structure and function of cephalopod jaws remains poorly known. Cephalopod jaws are unique as the two jaw elements do not contact one another, are embedded in a muscular mass and connected through a muscle joint. Previous studies have described the anatomy of the buccal mass muscles in cephalopods and have proposed variation in muscle volume depending on beak shape. However, the general structure of the muscles has been suggested to be similar in octopuses, squids, and cuttlefish. Here we provide a quantitative analysis of the variation in the buccal mass of coleoids using traditional dissections, histological sections and contrast-enhanced computed tomography scans. Our results show that the buccal mass is composed of four main homologous muscles present in both decapodiforms and octopodiforms as suggested previously. However, we also report the presence of a muscle uniquely present in octopodiforms (the postero-lateral mandibular muscle). Our three dimensional reconstructions and quantitative analyses of the buccal mass muscles pave the way for future functional analyses allowing to better model jaw closing in coleoids. Finally, our results suggest differences in beak and muscle function that need to be validated using future in vivo functional analyses.
与研究充分的关节脊椎动物颌骨相比，头足类动物颌骨的结构和功能仍知之甚少。头足类动物的颌骨很独特，因为两个颌骨元素彼此不接触，嵌入在肌肉块中，并通过肌肉关节连接。以前的研究描述了头足类动物的颊部肌肉解剖结构，并提出了根据喙形状的肌肉体积变化。然而，有人认为章鱼、鱿鱼和乌贼的肌肉结构大致相似。在这里，我们使用传统解剖、组织切片和对比增强计算机断层扫描对头足类动物的颊部质量进行了定量分析。我们的研究结果表明，颊部质量由四个主要的同源肌肉组成，这些肌肉在十足目和八腕目动物中都有存在，如之前所建议的那样。然而，我们还报告了一种仅存在于八腕目动物中的肌肉（后外侧下颌肌）的存在。我们对头足类动物颊部肌肉的三维重建和定量分析为未来的功能分析铺平了道路，使我们能够更好地对头足类动物的颌骨关闭进行建模。最后，我们的研究结果表明，喙和肌肉功能存在差异，需要使用未来的活体功能分析进行验证。
