2026-06-28T20:38:51Zhttps://docta.ucm.es/rest/oai/request

oai:docta.ucm.es:20.500.14352/1089472024-10-30T15:50:17Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc Takahashi, Sakiko author Ishizuka, Satoshi author Kitamura, Kei author Yang, Tianyi author Abe, Shinichi author Murakami, Gen author Rodríguez Vázquez, José Francisco author 2024-07-02 At the angle of the mouth, spoke-like muscle bundles converge at the "modiolus," which is believed to appear in utero. The aim of this study was to investigate the growth of the modiolus histologically. We studied frontal histological sections of the face from 12 midterm and six near-term fetuses. At midterm, a convergence of the levator anguli oris (LAOM) and depressor anguli oris (DAOM) was frequently present, and another convergence of the LAOM with the platysma (PM) or orbicularis oris (OOM) was also often evident. At near-term, muscle fiber merging or interdigitation was classified into nine combinations, five of which were frequently seen: LAOM-PM, LAOM-DAOM, zygomaticus major (ZMM)-orbicularis oris (OOM), buccinator (BM)-LAOM, and BM-PM. These combinations existed at slightly different depths and/or sites, thus allowing the angle of the mouth to receive multiple muscles. Notably, tissues interposed between the muscle fibers were limited to a thin epimysium at each crossing or interdigitation. Therefore, the LAOM, DAOM, OOM, BM, and PM appear to form a basic configuration at birth, but the development and growth were much delayed than the classical description. The modiolus is not a specific fibromuscular structure but simply represents a cluster of muscle convergence sites. Even at meeting between an elevator and depressor, a specific fibrous structure seems unlikely to connect the epimysium for the muscle convergence. Instead, the central nervous system appears to regulate the activity of related muscles to minimize tension or friction stress at the meeting site. Takahashi, S., Ishizuka, S., Kitamura,K., Yang, T., Abe, S.-i., Murakami, G. et al. (2024) Growthpatterns of facial muscles at the angle of the mouth: Ahistological study using midterm and near-term human fetuses.Journal of Anatomy, 245, 535–550 0021-8782 10.1111/joa.14101 https://hdl.handle.net/20.500.14352/108947 1469-7580 https://doi.org/10.1111/joa.14101 38953435 https://onlinelibrary.wiley.com/doi/10.1111/joa.14101 Growth patterns of facial muscles at the angle of the mouth: A histological study using midterm and near‐term human fetuses