Ligamentum flavum. Anatomy of the ligamentum flavum between adjacent laminae. The view is from the epidural space. The two ligamenta flava are completely fused in the midline (Photo taken at the Department of Anatomy, Innsbruck Medical University, Austria. Courtesy of L. Kirchmair, MD, and Prof. B. Moriggl, MD, FIACA)

Ligamentum flavum. Anatomy of the paired ligamentum flavum spanning out between adjacent laminae. The view is from the epidural space. Epidural fat fills the gap between the two ligamenta flava. Note the epidural fat, which is compartmentalized and fills substantial portions of the posterior epidural space (Photo taken at the Department of Anatomy, Innsbruck Medical University, Austria. Courtesy of L. Kirchmair, MD, and Prof. B. Moriggl, MD, FIACA)

Ligamentum flavum. Anatomy of the ligamentum flavum viewed from the epidural side (Photo taken at the Department of Anatomy, Innsbruck Medical University, Austria. Courtesy of L. Kirchmair, MD, and Prof. B. Moriggl, MD, FIACA)

Ligamentum flavum. Anatomy of the ligamentum flavum viewed from the epidural side (Photo taken at the Department of Anatomy, Innsbruck Medical University, Austria. Courtesy of L. Kirchmair, MD, and Prof. B. Moriggl, MD, FIACA)

Ligamentum flavum. Horizontal cross-section at the lumbar level detailing the tissues traversed during epidural or spinal puncture. In the figure can be identified skin, subcutaneous tissue, spinous processes joined by the supraspinous and interspinal ligaments, the lamina vertebrae, the ligamentum flavum (here with a very subtle midline gap), epidural space, and vertebral body. The white line indicates the needle direction for a perfect midline puncture (From Boon et al. [8]; with permission)

Anatomic variations in ligamentum flavum anatomy. The ligamenta flava are seen from the epidural space, featuring complete fusion of the two ligamenta (a), and continuous gaps along the entire height (b) (From Lirk et al. [2]; with permission)