SPIRAL LINE (SPL) We’ve teamed up with “Anatomy Trains” @anatomytrainsofficial and created a 3D visual of the SPL The Spiral Line (SPL) loops around the body in a double helix, joining each side of the skull across the upper back to the opposite shoulder, and then around the ribs to cross in the front at the level of the navel to the same hip. From the hip, the Spiral Line passes like a 'jump rope' along the anterolateral thigh and shin to the medial longitudinal arch, passing under the foot and