Transverse process view for lumbar neuraxial ultrasound

In the transverse process view, the transverse processes appear as hyperechoic, crescent-shaped reflections with hypoechoic, finger-like acoustic shadows below. The resulting pattern is referred to as the "trident," sign because of its similarity to the mythologic weapon. The psoas muscle is visualized between the transverse processes. For further detail refer to UpToDate content on neuraxial ultrasound for anesthesia.