Loin
The portion of the lower back from just below the rib cage to the pelvis.
The loins include the psoas muscles which are very powerful muscles in the lower back.
The term 'loin' is more often encountered now at the meat counter than in medicine.
It is also commonly encountered in the Bible, as in 'Gird up now thy loins like a man.' (Job 38:3).
The word 'loin' came from the Latin 'lumbus' which referred to the present day loin + the genitalia.