This paper aims to develop a structural continuum framework that accurately represents the anisotropic elastic properties of arterial layers, particularly the adventitia and intima, by accounting for the dispersion of collagen fiber orientations. The authors introduce a new hyperelastic free-energy function that generalizes previous models by incorporating a scalar structure parameter to characterize the dispersed collagen orientation. This generalization is crucial for capturing the mechanical response of these layers, which differ significantly from the media due to their fiber dispersion. The model is implemented efficiently using finite elements, and numerical examples demonstrate that the dispersion of collagen fiber orientations in the adventitia of human iliac arteries significantly affects its mechanical response. The study highlights the importance of considering the structural organization of arterial tissue in constitutive modeling to better understand and predict the behavior of soft biological tissues under mechanical loading.This paper aims to develop a structural continuum framework that accurately represents the anisotropic elastic properties of arterial layers, particularly the adventitia and intima, by accounting for the dispersion of collagen fiber orientations. The authors introduce a new hyperelastic free-energy function that generalizes previous models by incorporating a scalar structure parameter to characterize the dispersed collagen orientation. This generalization is crucial for capturing the mechanical response of these layers, which differ significantly from the media due to their fiber dispersion. The model is implemented efficiently using finite elements, and numerical examples demonstrate that the dispersion of collagen fiber orientations in the adventitia of human iliac arteries significantly affects its mechanical response. The study highlights the importance of considering the structural organization of arterial tissue in constitutive modeling to better understand and predict the behavior of soft biological tissues under mechanical loading.