The long, thick, fusiform psoas major lies lateral to the lumbar vertebrae. Psoas is a Greek word meaning “muscle of the loin.” (Butchers refer to the psoas of animals as the tenderloin.) The psoas major passes inferolaterally, deep to the inguinal ligament to reach the lesser trochanter of the femur. The lumbar plexus of nerves is embedded in the posterior part of the psoas major, anterior to the lumbar transverse processes.