A LITERARY REVIEW OF STHŪLA TWAK WITH SPECIAL REFERENCE TO ŚHĀRṄGADHARA SAṂHITĀ AND ITS ANATOMICAL CORRELATION

Background: Classical Ayurvedic authors describe Twak as a layered, living interface whose structure is inferred from appearance, sensation, disease location and surgical behaviour. In Śhārṅgadhara Saṃhitā, the seventh layer is named Sthūlā Twak, is measured as two vrīhi, and is identified as a site of Vidradhi. This description resembles Sushruta’s deepest Māṃsadharā layer but is often correlated uncritically with a single modern histological stratum. Objective: To critically examine the textual identity of Sthūlā Twak, compare it with other classical accounts, and propose an anatomically defensible modern correlation. Methods: A structured narrative review integrated primary Sanskrit passages, traditional commentarial interpretations, contemporary Ayurvedic reviews, and modern anatomical, histological and imaging literature. Claims were compared by terminology, sequence, measurement, function and pathology.Results: Śhārṅgadhara retains the seven-layer framework, the two-vrīhi magnitude and the association with deep suppuration, while replacing or simplifying the name Māṃsadharā to Sthūlā. Modern evidence does not support a one-to-one equation between the seven Ayurvedic layers and the five epidermal plus two dermal strata. Epidermal strata are microscopic, site-dependent and partly absent in thin skin; the dermis has no sharply bounded internal plane; and subcutis may or may not be counted as skin proper. The most coherent correlate is therefore a deep cutaneous functional compartment comprising the deep reticular dermis, dermis–hypodermis junction and superficial subcutis, with continuity toward fascia or muscle in advanced suppuration. Conclusion: Sthūlā Twak is best understood as a clinically perceived deep plane rather than an isolated microscopic layer. This interpretation respects the classical disease-based description while avoiding false anatomical precision. Future research should use predefined landmarks, high-frequency ultrasound and histopathology in anatomically matched sites.