Publications report observing tortuosity in the posterior intercostal arteries of elderly patients.  Studies also describe the size and course of the collateral intercostal arteries. This information is clinically significant when performing thoracentesis and video-assisted thorascopic surgery (VATS). To the best of our knowledge, no studies have examined arterial tortuosity or described collateral artery origins relative to boney landmarks. The purpose of this study was to define a safe surgical zone for thoracic access using palpable external boney landmarks. Three-hundred forty-eight intercostal spaces (3^rd – 8^th) of 29 male and female embalmed cadavers were dissected from the vertebral body to the mid-axillary line to observe the posterior intercostal artery and its collateral branch. The origins of the collateral intercostal arteries relative to the midline of thoracic spinous processes were measured. Mild to moderate tortuosity (arterial curves covering 25-50% of the intercostal space) was observed in at least one posterior intercostal artery in the majority of cadavers. The origins of the collateral intercostal arteries were variable relative to the midline. Additional collateral intercostal arteries distal to the primary collateral branch were observed, most commonly in the 5^th intercostal space, which is used in VATS and thoracentesis. Tortuosity is common in the third through eighth posterior intercostal arteries, especially in individuals over the age of 60. Given the findings of this study, we recommend that any procedure involving placement of a surgical instrument into these intercostal spaces do so at least 120 mm lateral to the midline of the spinous processes. We also recommend pre-procedure ultrasound (intercostals scan) of the posterior and collateral intercostal arteries when performing non-emergent thoracentesis and video-assisted thorascopic surgery, particularly in patients over 60 years of age.