What Is Inside the Sinus Tarsi? Mechanoreceptor Distribution, Typing and Clinical Relevance—A Histological and Immunohistochemical Synthesis

The sinus tarsi, a small osseoligamentous recess of the subtalar joint, contains multiple soft-tissue structures with a complex sensory network. However, the detailed neural architecture and clinical significance of its innervation remain incompletely defined. The aim of this study was to conduct a comprehensive review of histological and immunohistochemical studies on the neural structures of the sinus tarsi. Histological staining and validated immunohistochemical markers (S100, p75, PGP9.5, neurofilament, myelin basic protein) were the methods used in these studies to analyze human sinus tarsi tissue. Across all investigations, free nerve endings predominated, while Ruffini, Pacinian and Golgi-like corpuscles were variably identified, mainly near ligament insertions. The sinus tarsi exhibits a dense and heterogeneous neural network that likely contributes to both pain perception and sensorimotor control. Further standardized and quantitative research is warranted to clarify the neurofunctional role of this region.