The growth and developmental of the myodural bridge and its associated structures in the human fetus

The myodural bridge (MDB) is a dense connective tissue structure between the suboccipital musculature and the spinal dura mater (SDM). However, few reports on the development and maturation of the human MDB. 30 head and neck specimens from human fetuses (F) from 12–40 weeks (W) were made into histological sections. The F12W sections evidenced that the SDM dominated by fibroblasts, attached to the posterior atlantoaxial membrane (PAAM) which completely sealed the atlantoaxial space. In the F13W stage, myofibrils of the suboccipital muscle fibers increased significantly in number. At the F14W stage, a gap was observed at the caudal end of the PAAM. Numerous myodural bridge-like structures were observed blending into the SDM through the gap. At the F15W stage, the MDB fibers originated between the posterior arch of atlas (C1) and the obliquus capitis inferior muscle, and extended forward and downward into the spinal canal through the atlantoaxial gap. Starting at the F21W stage, the MDB fibers were observed to pass through the atlantoaxial interspace and radially attach to the SDM. The present study adds to the knowledge base of developmental morphology research of the human embryonic MDB and provides a developmental morphological basis for its potential functionality.