Table 2.

The comparison of anatomical investigations.

			Ivanusic et al.	Adhikary et al.	Sabouri et al.	Yang et al.
Target of the investigation			ESPB	RLB and ESPB	RLB	RLB and ESPB
Method			20 injection in 10 cadavers	3 injection per each block	8 injection in 8 cadavers	10 injection per each block
Cadaver			unembalmed/fresh cadavers
Injection level			T5 vertebral level	T5 vertebral level	T4 vertebral level	T5 vertebral level
Injectate volume			20 ml of mixture
The spread of dye	Anterior	Paravertebral space	none	possible in both blocks	possible (quite variable)	limited spread
		Epidural space				no details
		Intercostal space				no details
	Posterior		The dorsal ramus was frequently stained.	RLB: beneath the transversospinalis muscles ESPB: beneath the erector spinae muscles	The dye spread beneath the paraspinal muscles.	RLB: the surface of the transversospinalis muscle ESPB: the surface of the external intercostal muscle
	Lateral		The dye often spread to the attachments of iliocostalis muscle.	ESPB > RLB RLB: to the edge of the bony lamina ESPB: extending 9 to 10 cm lateral	median lateral spread 2.5cm	RLB < ESPB RLB: limited medially to the intertransverse ligaments ESPB: spread to iliocostalis muscle
	Longitudinal		The majority of the dye spread was cephalad to T6.	ESPB > RLB RLB: 6-9 vertebral levels ESPB: 9-14 vertebral levels	median cephalad spread 3.5cm caudad spread10.7cm	spinal nerve involvement: RLB (2 levels) > ESPB (3.5 levels)

RLB: retrolaminar block and ESPB: erector spinae plane block.