Background:The proper functioning of the lumbosacral complex requires the integrated activity of all its components. Proper segmental control of the lumbosacral region of the spine and its stabilization are required.Aims: This study aimed to determine the morphometry of the musculofascial structures of the lumbosacral region of the spine in young subjects with no history of lower back pain, and the gender differences in the thickness of these anatomical structures. Material and methods:The study included 20 subjects who underwent ultrasound examinations to estimate the thickness of the musculofascial structures of the lower spine. For the purpose of this study, two zones were distinguished: muscular zone (MZ) and perimuscular zone (PMZ). In the MZ, the thickness of the multifidus muscle (MFM) was measured. In the PMZ, the thickness of the following structures was measured: epimysium of the multifidus muscle (EMFM), loose connective tissue (LCT), and thoracolumbar fascia (TLF). The collected thickness measurements were analyzed as the average values from both sides of the body.Results: Differences in MFM thickness were observed between men and women, while no differences were noted in the other measurements in the PMZ. Conclusions:Resting MFM thickness is greater in men, whereas the resting thicknesses of the TLF, LCT, and EMFM are similar for both genders in the lumbosacral complex.