The midline interlaminar ligament (MIL) is a recently identified anatomical structure situated between the right and left ligamenta flava (LFs) within the vertebral canal. It was initially described in the lumbar spine, but subsequent research has confirmed its presence across cervical and thoracic levels, albeit with markedly lower prevalence. This review synthesizes findings from two key studies to provide a comprehensive account of the MIL’s anatomical features, biomechanical properties, and potential clinical significance. The ligament appears consistently in the lumbar spine, where it is probably involved in spinal stabilization, particularly in extension. Histologically, the MIL is less elastic than the LF but has a higher concentration of nerve fibers, suggesting possible proprioceptive and nociceptive functions. While its exact physiological role remains to be clarified, the identification of the MIL opens new avenues for understanding spinal mechanics, low back pain, and the anatomical considerations relevant to lumbar puncture and epidural anesthesia.