What forms the inferior border of the Quadrilateral Space?

• A. Teres Minor
• B. Teres Major
• C. Long Head of Triceps
• D. Humeral Shaft

Answer: (B)

The inferior border of the Quadrilateral Space is defined by the Teres Major muscle. This is significant in the context of the shoulder anatomy, particularly as it relates to the potential passage of neurovascular structures.

The Quadrilateral Space is bordered laterally by the surgical neck of the humerus and superiorly by the Teres Minor. The placement of the Teres Major as the inferior boundary provides a critical reference point for understanding the spatial relationships between the structures that traverse this space, such as the axillary nerve and the posterior circumflex humeral artery. This anatomical delineation is crucial during assessments and interventions related to shoulder injuries, surgical approaches, and even for interpreting imaging studies.

Understanding this anatomy helps clinicians locate pathologies, plan surgical interventions safely, and recognize the implications of trauma involving the quadrilateral space, which can affect shoulder function and strength. The role of the Teres Major as the inferior border thus becomes a cornerstone for grasping shoulder mechanics and the potential complications arising from injuries.