The upper branch passed along the base of axilla, then left the axilla by passing through lower triangular space and finally joined with posterior cutaneous nerve of arm on each side whereas the lower branch passed along the base of axilla to reach the upper and medial part of arm where they join with medial cutaneous nerve of arm on each side.
The upper branch of 1st intercostobrachial nerve passed along the base of axilla, then left the axilla by passing through lower triangular space and finally joined with posterior cutaneous nerve of arm on each side whereas the lower branch passed along the base of axilla to reach the upper and medial part of arm where they join with medial cutaneous nerve of arm on each side.