Mnemonic

Triangular Interval, Triangular Space and Quadrangular Space

A memory aid for the contents of the three intermuscular spaces at the back of the shoulder.

Expansion

Triangular space holds the circumflex scapular artery; quadrangular space holds the axillary nerve; triangular interval holds the radial nerve

Expansion

  • Triangular space - transmits the circumflex scapular artery
  • Quadrangular space - transmits the axillary nerve and posterior circumflex humeral artery
  • Triangular interval - transmits the radial nerve and the profunda brachii (deep brachial) artery

The long head of triceps is the shared landmark that separates them.