All of the following forms the boundaries of the lower triangular space of arm, EXCEPT:
Boundaries of lower triangular space of arm are: medially it is bounded by long head of triceps, laterally by medial border of humerus and superiorly by teres major. Radial nerve and profunda brachii vessels are the contents of the lower triangular space. Ref: Human anatomy by B.D Chaurasia, 4th Edition, Vol 1 Page 81
Teres major
Shaft of humerus
Pectoralis major
Long head of triceps