Temporoparietalis Muscle: A Cadaveric Study of 60 Hemisides

The temporoparietalis muscle (TPM) is a thin, fan-shaped muscle continuous with the superficial musculoaponeurotic system and galea aponeurotica. Despite frequent surgical use of the temporoparietal fascia, TPM anatomy and its variability remain incompletely characterized.

Thirty embalmed cadavers (60 hemisides) underwent a standardized, stepwise layered dissection of the lateral scalp to expose the temporoparietal fascia and the plane deep to it. Using an a priori operational definition and prespecified visual criteria, each hemiside was categorized as (1) visibly thick TPM, (2) present but indistinct TPM, or (3) absent TPM. Proportions are reported with Wilson 95% confidence intervals (CIs).

TPM was identified on 37 of 60 sides (61.7%; 95% CI, 49.0-72.9). Visibly thick TPM was present on 10 of 60 sides (16.7%; 95% CI, 9.3-28.0), and present but indistinct TPM was identified on 27 of 60 sides (45.0%; 95% CI, 33.1-57.5). TPM was absent on 23 of 60 sides (38.3%; 95% CI, 27.1-51.0).

TPM is present in approximately three-fifths of hemisides but is conspicuously robust in only one-sixth. Anticipating this variability may help surgeons interpret temporal dissection planes and may refine operative planning in procedures involving the temporoparietal region.