A thorough anatomical knowledge of the normal conformation and variations of the brachial plexus, its branches and the vessels with which they are related is of paramount importance for anatomists, surgeons, anesthesiologists and radiologists. During routine anatomical dissection of the left axilla and supraclavicular region of a 69 year-old male preserved corpse, the medial root of the median nerve was found to receive a supplementary branch from the medial aspect of the terminal portion of the lateral cord. This anastomotic branch crossed in a narrow space between the axillary artery and the deep brachial artery that originated unusually proximally from the third portion of the axillary artery. To our knowledge, the association of this type of origin of the median nerve with a deep brachial artery deriving from the axillary artery has not been cited in recent medical literature. This particular disposition of the origin of the median nerve could help explain why, in some cases, injury of the lateral cord or upstream to the lateral cord may lead to the unexpected presentation of weakness of forearm flexors and thenar muscles.