The iliocostalis portion of the erector spinae muscle is a long, thin muscle located in the posterior aspect of the thoracic and lumbar regions of the spine. It is one of the main muscles responsible for extending the spine, and is important for activities such as standing, walking, and lifting objects. The iliocostalis portion of the erector spinae muscle originates at the sacrum and the iliac crest, and then inserts at the ribs and the transverse processes of the vertebrae.

In terms of function, the iliocostalis portion of the erector spinae muscle is one of the primary muscles responsible for extending the spine. This movement is important as it helps to maintain an upright posture and keep the spine in a neutral position. The iliocostalis portion of the erector spinae muscle also plays a role in providing stability to the spine, which is important for preventing falls and protecting the spinal cord from injury.

In terms of daily uses, the iliocostalis portion of the erector spinae muscle is active whenever we stand, walk, or perform any other activity that involves extending the spine. It is also used when we lift objects, climb stairs, or perform movements that require stability of the spine, such as standing on one leg or performing single-leg exercises. The iliocostalis portion of the erector spinae muscle is important for activities that require strong spinal extension and activities that involve sudden changes in direction.