The posterior border of the TPVS. The SCTL runs from the TP above to the rib below and forms a major part of the posterior wall of the thoracic paravertebral space. Note that the SCTL runs obliquely from cranial to caudad and from lateral to medial. The ventral surface of the SCTL is at a similar depth to the ventral surface of the TP. Note the gaps in the SCTL.