Spina vestibuli, or vestibular spine, is a bony structure, in anatomical terms a 'mesenchymal condensation', which extends from the mediastinum of the heart and covers the leading edge of the primary atrial septum; its origin is outside of the heart. Below the opening of the orifice of the coronary sinus they fuse to form a triangular thickening — the spina vestibuli.
Spina vestibuli, or vestibular spine, is a bony formation, in anatomical terms a 'mesenchymal condensation', which extends from the mediastinum of the heart and covers the leading edge of the primary atrial septum; its origin is outside of the heart. Below the opening of the orifice of the coronary sinus they merge to form a triangular thickening — the spina vestibuli.