Sacrum if you're asking about the skeletal system
Costovertebral is the medical term meaning pertaining to the spine and ribs.
lumbosacral
It will be called the Lumbar regionLumbar
"Lumbar" refers to the region of the back or spine made up of the lumbar vertebrae. The 1st lumbar vertebra is just under the 12th thoracic vertebra. The easiest way to find this is to find the first vertebral body not connected to a rib. This is L1 (1st lumbar vertebra). There are 5 lumbar vertebrae (L1 through L5). The 5th lumbar vertebra sits on top of the sacrum (where your spine connects with your pelvis).
Lumbar puncture.
I think you are trying to describe a Lumbar Puncture, which is performed in the lower (lumbar) region of the spine.
A "spinal tap" is also known as a "lumbar puncture".Lumbar puncture
Sciatica is the medical term meaning inflammation of the sciatic nerve.sciaticasciatica
Sciatic
A strain is a medical term meaning there has been abnormal stretching on a muscle and its tendons. This generally causes a painful contraction of the muscle in an attempt to protect itself from further damage. A lumbar strain is a strain in the lumbar region of the back, specifically, the region of the back from below the ribcage to where the spine attaches to the pelvis. This is a very common cause of back pain.
It's all part of your spinal cord. The lower sections are the lumbar vertebrae and then finally the sacral vertebrae.
Lumbar Puncture