Thoracic Spine Rule of Threes Mnemonic

The first rule states that the spinous processes for T1-T3 are located at the same level of the corresponding transverse process. For example, if a physician palpates the T3 spinous process, then they are directly in line with the bilateral T3 transverse processes.

The second rule states that the spinous processes for T4-T6 are located at a one half segment below of the corresponding transverse process. For example, if a physician palpates the T5 spinous process, then they are a half segment below the bilateral T5 transverse processes. To locate the T5 transverse process, they should palpate a half segment above and move laterally along the spine.

The third rule states that the spinous processes for T7-T9 are located one full segment below of the corresponding transverse process. For example, if a physician palpates the T8 spinous process, then they are a one segment below the bilateral T8 transverse processes. To locate the T8 transverse process, they should palpate one segment above and move laterally along the spine.

For the final thoracic vertebral spinous processes, we reverse the three rules for each subsequent segment. For T10, we follow Rule 3 (same as T7-T9). For T11, we follow Rule 2 (same as T6-T4). For T12, we follow Rule 1 (same as T1-T3).