From the superior end of the sacrotuberous ligament,our rules require that we keep going in roughly the samedirection, and we have no trouble doing that: the erectorspinae arise from the layers of sacral fascia continuouswith the sacrotuberous ligament The erector spinae span the spinefrom sacrum to occiput, with the expresses of the longis-simus and iliocostalis complex overlying the ever deeperand shorter locals of the spinalis, semispinalis, and mul-tifidus . The deepest layer, the transversospinalisgroup, provides the shortest one-joint locals, which revealthe three basic patterns followed by all the erector muscles. The functional anatomical details of all thesemuscle complexes have been ably covered elsewhere.2–4The most superficial express layers of fascia in thiscomplex tie sacrum to occiput. We should note that eventhough the erectors are part of what is termed the Superfi-cial Back Line, several layers of even more superficial myo-fascia overlie the line here in the form of the serratusposterior muscles, the splenii, the rhomboids, the levatorscapulae, and the superficial shoulder musculature of thetrapezius and latissimus dorsi. These muscles form parts ofthe Spiral, Arm, and Functional Lines, and are addressed inChapters 6, 7, and 8, respectively.