Aim: The morphological diversity of the brachialis tendon insertion and its connections to the neurovascular systems of the arm. Materials and Methods: The research was carried out on fifty upper limbs taken from preserved human cadavers stored in the Department of Anatomy. An incision was made along the length of the anterior surface of the brachial fascia, beginning at the level of the pectoralis major muscle and ending at the elbow. The limbs were dissected as part of standard procedure in order to study the insertion of the brachialis muscle and its relationship to the neurovascular systems in the arm. Observations were made on the path taken by the median nerve and the brachial artery. Results: The brachialis muscle is inserted into the anterior side of the coronoid process and the tuberosity of the ulna in 48 out of 50 specimens (96%) of the study's participants. Both the median nerve and the brachial artery go superficially via the brachialis muscles, and the interaction between the two structures was normal. In two of the specimens, or 4% of the total, brachialis muscles in the bottom third of the right upper limbs formed a tunnel. It was estimated that the length of the tunnel was about 2.6 centimetres. It was only present in one arm of the corpse, but the other arm, which was the left one, seemed normal. In this particular instance, entrapment of the brachial artery as well as the median was found inside the tunnel formed by the brachialis. Conclusion: As a result, having information about these kinds of uncommon mutations is essential for surgeons in order to prevent providing incorrect diagnoses and treatments.