Collagen fibre orientation in the human temporal fascia

Animal experiments and computer simulations suggest that the temporal fascia may play an important mechanical role in stabilising the zygomatic arch during mastication and contribute to the normal growth of the zygomatic arch by transferring forces to the bone. Measurements of these forces are difficult to obtain in vivo but collagen fibre orientation can provide useful information, as collagen fibres are aligned with the main force directions in connective tissues. In this study, we aimed to visualise and measure the collagen fibre orientation in the human temporal fascia to learn more about the mechanical forces that act on the fascia and the zygomatic arch.

Temporal fascia samples were extracted from three areas of superficial and deep temporal fascia in human cadaveric specimens. Samples were stained histologically for collagen and imaged with confocal microscopy. Images were analysed using ImageJ software to determine collagen fibre orientation.

We measured a predominantly superoinferior orientation of collagen fibres in both superficial and deep human temporal fascia layers. The 3D visualisation of selected sample areas suggested that the fibres have multiple orientations within each fascia sheet, similar to an interwoven network. In addition, we observed a large variation in the thickness of the fibres within and between the two fascia layers.

The predominant superoinferior orientation of the collagen fibres corroborates the hypothesis that the temporal fascia plays a role in stabilising the zygomatic arch during mastication by counteracting the inferior pull of the masseter muscle. However, the large variation of fibre orientation within the fascia layers suggests that the temporal fascia has to distribute forces in multiple directions.

This study was approved by a Licensed Teacher of Anatomy. No other ethical approval was required. We are grateful to the individuals who facilitated this cadaveric study by their generous body donations.