Which muscle serves as the superior border of the Quadrilateral Space?

• A. Infraspinatus
• B. Teres Major
• C. Teres Minor
• D. Subscapularis

Answer: (C)

The correct answer is Teres Minor, which serves as the superior border of the Quadrilateral Space. This anatomical space is clinically significant because it contains important neurovascular structures, including the axillary nerve and the posterior circumflex humeral artery. The Teres Minor is a small muscle located on the posterior shoulder, and it functions primarily to externally rotate the humerus and assist in shoulder stabilization.

In terms of anatomy, the quadrilateral space is defined by four borders: superiorly by the Teres Minor, inferiorly by the Teres Major, laterally by the humerus, and medially by the long head of the triceps. Understanding these relationships is crucial for diagnosing and treating shoulder pathologies, especially those involving the axillary nerve or vascular supply to the shoulder region.

This visual and functional relationship of the Teres Minor as the superior border is essential for clinicians when assessing shoulder injuries, as it helps in identifying the areas to focus on during examinations or imaging studies.