Morphogenesis and functional aspects of the muscular layer of the middle deep cervical fascia in humans.

Abstract

Background: In recent years, the fasciae of the human body have received significant attention because of their crucial role in the transmission of muscle force. However, studies on the development of the fasciae, particularly the cervical fascia, remain scarce.

Purpose: This study was performed to examine the development of the fascia of the infrahyoid strap muscles, also known as the middle layer of the deep cervical fascia (MDCF), in 17 human embryos aged 6-8 weeks and 20 human foetuses aged 9-14 weeks.

Methods: Histological examination of serial sections was performed using conventional light microscopy.

Results: Three stages in the development of the MDCF were identified: the initial, formation, and maturation stages. In the initial stage (week 6 of development, Carnegie stages 18-19), the mesenchymal primordium of the epimysium of the infrahyoid muscles was observed and found to be continuous with the mesenchymal primordium of the MDCF. The infrahyoid muscles already exhibited intramuscular fibres, the primordium of the perimysium, and the endomysium. In the formation stage (weeks 7-8 of development, Carnegie stages 20-23), fibroblast-like cells and collagen fibres appeared in the primordium of the muscle epimysium and in the MDCF. Intramuscular fibres had become very evident. In the maturation stage (from week 9 of development onward), further development and organisation of the fascial structures occurred.

Conclusion: Our results suggest that the MDCF of the neck develops in parallel with the mechanical activity of this region. The relationship between the MDCF and the lymphatic and venous structures of this region suggests that the MDCF may facilitate venous and lymphatic circulation.