Lateral triangular space
The lateral triangular space is a space connecting the axilla to the posterior compartment of the arm. It is also called the triangular interval or lower triangular space 1. It should not be confused with the similarly named medial (upper) triangular space.
It is a downwards pointing triangle with a base superiorly and apex inferiorly.
- long head of triceps brachii muscle (medial margin)
- teres major muscle (inferior margin)
- humerus (lateral margin)