Bones

Lumbar vertebrae (L1-L5)

Intervertebral discs

Discs located between each lumbar vertebra

Muscles

Erector spinae group (iliocostalis, longissimus, spinalis)

Multifidus 

Quadratus lumborum

Ligaments

Anterior longitudinal ligament

Posterior longitudinal ligament

Ligamentum flavum

Joints

Facet Joints

Nerves

Lumbar spinal nerves (L1–L5)