Within the depth-psychology and embodied-cognition corpus, ‘muscle’ functions less as an anatomical curiosity than as a primary medium through which psychological states — threat, anxiety, immobilization, and vitality — are registered and perpetuated in the body. Fogel establishes the most sustained treatment, situating muscle tension within a dynamic system linking emotion, posture, and embodied self-awareness: chronic muscular holding is shown to correlate reliably with anxiety disorders and to co-constitute, rather than merely express, psychological disturbance. Levine extends this into clinical territory, reading muscle flaccidity as the somatic signature of immobilization-system dominance and muscular aliveness as the target of trauma recovery. Damasio frames skeletal muscle as the substrate of body-map updating — the continuous contraction and distension of muscle fibers generating the bodily configurations whose brain-maps underwrite consciousness and selfhood. At the neurobiological stratum, Kandel and Craig examine muscle’s role in signaling: Craig’s lamina I spinobulbar neurons responsive to muscle contraction provide the substrate for the exercise pressor reflex, linking interoceptive homeostatic monitoring to muscular activity. Feinstein’s floatation data demonstrate measurable psychological benefit through environmentally induced muscle-tension reduction. Taken together, these voices establish muscle as an irreducible site where physiology, affect, posture, and self-regulation intersect — a theoretical locus that neither purely somatic nor purely psychological frameworks can adequately address alone.