Deciphering the Refined Musculature of the Brow Area in Asians by Micro-Computed Tomography.

Background: The brow area is an important aesthetic unit. Accurate anatomical understanding of the brow is important for clinical treatments related to this region. Due to the complexity of the brow area and limitations of methods, there are still some controversies regarding its musculature description.

Objectives: This article aims to reveal the detailed musculature using micro-computed tomography (micro-CT) combined with histological staining.

Methods: Eight fresh cadaver (16 hemifaces) were obtained. Eight hemifaces were processed with phospho-tungstic acid contrast staining for micro-CT scanning and reconstruction. The other corresponding 8 hemifaces were prepared with Masson staining.

Results: The orbicularis oculi muscle (OOM), frontalis muscle (FM), depressor supercilii (DS) and procerus muscle (PM) were situated superficially. The FM terminated and connected with its antagonistic muscles at 2-5 mm above the brow but the fusion line descended in lateral third. The corrugator supercilii muscle (CSM) originated from the periosteum, extending laterally and superficially. During its course, it mainly penetrated the FM. CSM had broad subcutaneous insertion, covering about 77.9% ± 7.5% of the hairy brow. CSM fibers connected to the subcutaneous fiber septa to directly transmit contraction force. The soft tissue on the lateral side of the brow was looser than that on the medial side.

Conclusions: Our study deepens the understanding of the precise anatomy of the brow area and helps guide clinical practice.