Fig. 3From: Distribution and imaging characteristics of spina bifida occulta in young people with low back pain: a retrospective cross-sectional studya The width of the two sides of the lamina is narrow from the beginning of development, resulting in the failure of fusion with the adjacent lamina below, forming a wide fissure on the surface of the sacrum, as shown in b. c The left lamina narrows gradually with the development process, as shown in dBack to article page