Reappraisal of the morphological and morphometric study of the psoas minor muscle with clinical and developmental insights: cadaveric study

Background: The Psoas Minor (PMi) is the most unstable muscle of the psoas group of the posterior abdominal muscle. This muscle has a fusiform shape and consists of a short fusiform belly continuing distally as a long tendon inserted on the pecten pubis and the iliopectineal arch. The present study was conducted to obtain more detailed information about the muscle and to expand knowledge about its morphology and morphometry. Materials and methods: The posterior abdominal wall of 30 adult cadavers was dissected. Anatomical variabilities in origin, insertion, length, width, and muscle-to-cone ratio were measured when PMi was found. The data collected was interpreted descriptively. Results: PMi was found in 12 cases, ten bilateral and two unilateral. The origin was constant in all cases and, except for three cases, extended into the iliac fascia and the iliopubic eminence. Morphometric analysis revealed that the average length of the proximal muscle belly and distal tendons was 4.52 ± 1.35 cm and 13.05 ± 0.90 cm, respectively. The mean width of the muscle belly was 1.71 ± 0.17 cm, and that of the tendon was 0.47 ± 0.10 cm. On average, the muscle belly occupied the proximal 33.71 ± 6.15% of the total musculotendinous unit. Conclusions: Findings confirm the inconsistency of PMi in the study population. Morphological variations became more evident as the tendon approached the insertion level. The muscle's distal attachment to the iliac fascia may partially control the position, mechanical stability of the underlying iliopsoas and this circumstantial function may be clinically related to iliopsoas inflammation and pathology. However, further studies recommended to determine biomechanical validity and clinical applicability of this vestigial muscle in human.