SCALP and temporal fascia in the cranio-orbito-zygomatic approach: highlighting the interfascial dissection plane

Cranio-orbito-zygomatic approach (COZA) requires adequate SCALP, fascia and muscle retraction to access the zygomatic arch, malar eminence (ME) and inferior orbital fissure (IOF), which endanger the facial nerve branches. Performing skull base reconstruction also demands a layer-by-layer understanding of the SCALP and fasciae. We aimed to examine the relationship between the SCALP layers, temporal fascia (TF) and facial nerve branches from a surgical viewpoint and highlight the optimal dissection plane during the COZA.

The SCALP and temporal fascia layers were examined using COZA on 10 formalin-fixed cadavers (20 sides). Stepwise dissections analyzed the relationships between SCALP layers, temporoparietal fascia, TF and facial nerve branches. In addition, facial dissections were conducted to examine the relationships between the facial nerve branches and the associated fasciae.

The temporoparietal fascia was continuous with the galea superomedial to superior temporal line. Facial nerve branches coursed between the galea and the TF. The TF divided into superficial and deep layers; superficial layer continuous with the pericranium and extending anteriorly toward periorbita. Following the superficial layer of the TF inferiorly provided a natural interfascial surgical plane for exposure of the ME. Deep layer of the TF further divided into medial and lateral laminae with an interfascial fat pad between them. The lateral and medial laminae attached to the lateral and medial surfaces of the zygomatic arch, respectively, and merged at the superior margin.

Recognizing the interfascial plane between the superficial and deep layers of the TF and the deep interfascial fat pad, may improve surgical orientation and facilitate tissue retraction during exposure of the lateral orbital wall and ME in the COZA.