psoas minor (muscle)

pso·as mi·nor (mus·cle)

[TA]
an inconstant muscle, absent in about 40%; origin, bodies of twelfth thoracic and first lumbar vertebrae and disc between them; insertion, iliopubic eminence via iliopectineal arch (iliac fascia); action, assists in flexion of lumbar spine; nerve supply, lumbar plexus.