Thoracic Intervertebral Foramen Block

The investigators hypothesize an alternative way to perform thoracic paravertebral block, by placing the needle tip over and behind the transverse process of vertebra, via the thoracic intervertebral foramen. This anesthetic procedure is called thoracic intervertebral foramen block. The study aims to verify the spread of dye on to the the nervous structures of retropleural space (the ventral rami, the communicating rami, and the sympathetic trunk), and into the thoracic paravertebral space and epidural space. To accomplish this, a prospective cadaveric study was designed.