Human major psoas muscle and sacrospinalis muscle in relation to age: a study by computed tomography

The size and density of the major psoas and sacrospinalis muscles in humans were measured in vivo by X-ray computed tomography to determine the relationship of age and sex of these two muscles. Measurements of 44 men and 52 women clarified patterns of development and aging. Differences due to age were significant in the density of both muscles. There existed also a difference between the sexes in the size of the two muscles.