Vertebral Level of the Inferior Angle of the Scapula
The inferior angle of the scapula (IAS) in the upright position most commonly aligns with the T8 spinous process, not T7 as traditionally taught. 1
Evidence-Based Location
The mean spinal level for the IAS is the T8 spinous process (corresponding to the upper T9 vertebral body on anteroposterior radiographs), with a range from T4 to T11. 1
A systematic review and meta-analysis pooling data from 5 studies demonstrated normal distribution with the upright IAS aligning closely with T8 SP on average. 1
Individual radiographic analysis found the left IAS at midway between the T8-9 interspace and upper T9 body (range: lower T7 to upper T10), while the right IAS was slightly lower but still within upper T9 body (range: lower T7 to lower T10). 2
Clinical Variability
Approximately 68% of patients will have their IAS located at T7, T8, or T9, indicating substantial individual variation. 3
The modes for IAS placement across studies were consistently at T8, with T7 and T9 as the next most common locations. 3
Positional Changes
The scapula moves caudad (downward) when patients assume prone positions, contrary to common belief that it moves cephalad. 4
In prone positioning with arms on armrests (the most common clinical posture), the IAS moves approximately one vertebral level caudad, averaging 18.4 mm of downward movement. 4
Only two prone positions caused cephalad movement: arms at side and "chicken-wing" position. 4
Clinical Implications
Health professionals using the traditional T7 landmark rule have likely been targeting spinal levels different from those intended, potentially one level too high. 1
Manual therapists, acupuncturists, anesthesiologists, and surgeons should reconsider their procedures for identifying spinal sites based on this corrected anatomical relationship. 1
Experienced palpators can accurately locate vertebral levels 3 above or below a given landmark, with average errors of only 0.26 levels cephalad and 0.21 levels caudad. 3