Fig. 10.  Transverse interlaminar view of the lumbar spine and corresponding magnetic resonance imaging scan (T1-weighted). The intrathecal space is a dark hypoechoic band sandwiched between the hyperechoic posterior and anterior complex. The transverse processes and articular processes lie in the same transverse plane and are usually visible. The ligamentum flavum, posterior epidural space, and dura often cannot be distinguished from one another in the transverse view. The midline is indicated by the dark vertical stripe of the interspinous ligament. (Image used with permission from www.usra.ca.)