According to Miller, Figure 59-52, the paramedian approach to the epidural space is now favored by most anesthesiologists at the midthoracic levels. The needle is inserted 1 cm lateral to the superior tip of the spinous process and then advanced perpendicular to all planes to contact the lamina of the vertebral body immediately below. The needle is “walked” up the lamina at an angle rostrally (45 degrees) and medially (20 degrees) until the rostral edge of the lamina is felt. The needle is advanced over the edge of the lamina, seeking a loss of resistance on entering the epidural space after transversing the ligamentum flavum.
The layers passed through in a paramedian approach are (from superficial to deep) skin, subQ fat, ligamentum flavum, dura mater, sudural space, arachnoid mater, and subarachnoid space.