Importance of Teres Minor Muscle Morphometry in Rotator Cuff Injury

Background: Teres minor (TMi) is a small rotator cuff muscle which forms the boundary of the quadrangular space. The hypertrophy of TMi may result in compression of the neurovascular structures present in space such as axillary nerve and posterior circumflex humeral vessels. Thus, the compression in this space may lead to neurogenic radicular pain, paresthesia, tenderness, and vascular symptoms such as ischemia and cyanosis of rotator cuff. Several cases of rotator cuff injuries have been observed where TMi comes out as the chief muscle for external rotation in case of tears of the supraspinatus and infraspinatus. In case of arthroplasty of shoulder joints, the TMi muscle function is an important prognostic factor. The present study is carried out to understand the morphometry of TMi with respect to its length, width, and thickness during muscle repair and tendon transfer surgeries. Materials and Methods: The present study utilized 40 adult embalmed cadavers. The length of TMi was measured from its origin to insertion. The length of the tendon was measured using a measuring tape. The width of the muscle is measured from the upper, middle, and lower parts using a measuring tape, and the thickness is measured with a Vernier caliper. Results: The length, width, and thickness of the TMi muscle were measured at 11.35 ± 1.2 mm, 1.5 ± 0.34 mm, and 0.72 ± 0.23 mm, respectively. This measurement can be used to confirm hypertrophy and atrophy of the TMi muscle in case of rotator cuff injury in adults. The length of the tendon was 3 ± 0.79 mm. The right and left TMi muscle morphometry was noted same on both sides. Conclusion: The morphometry of TMi might play an important role in understanding of neurovascular compression in the quadrangular space, arthroplasty of shoulder joints, and tendon tear injuries of rotator cuff.