Subscapular Spaces are quadrangular (1) and triangular (2) intermuscular spaces in the scapular region, that are clearly viewed from behind after reflecting the posterior part of the deltoid. The knowledge of these spaces is necessary during surgery in the shoulder region.

Quadrangular Space

Boundaries

Superior:

  • Teres minor (posteriorly).
  • Subscapularis (anteriorly).
  • Capsule of shoulder joint between the above 2 muscles.

Inferior: Teres major.

Medial: Long head of the triceps.

Lateral: Surgical neck of the humerus.

Structures Going Through This Space

1. Axillary nerve.

2. Posterior circumflex humeral artery and vein.

Upper Triangular Space

Boundaries

  • Superior: Teres minor.
  • Lateral: Long head of triceps.
  • Inferior: Teres major.
  • Structure going through this space: Circumflex scapular artery (this artery interrupts the origin of teres minor to reach the infraspinous fossa).

Lower Triangular Space

Boundaries

  • Medial: Long head of triceps.
  • Lateral: Shaft of humerus.
  • Superior: Teres major.

Structures Going Through This Space

  • 1. Radial nerve.
  • 2. Profunda brachii artery and vein.