Introduction: In most of cases, the emergency of the nervous roots of the brachial plexus in the posterior cervical triangle occur between the anterior and middle scalene muscles. However, anatomic variations in the brachial plexus are not rare. Methods: In the laboratory of Human Anatomy of the "Faculdade de Ciências Médicas de Minas Gerais" 106 cadavers were dissected. There were dissected the cervical region of all of the cadavers bilaterally. Results: In routinely dissection in the laboratory of human anatomy of the "Faculdade de Ciências Médicas de Minas Gerais" we've found in the left cervical region of a male cadaver the ventral branch of the seventh cervical nerve (C7) perforating the substance of the middle scalene muscle. Conclusion: Professionals that work with this region on the practice must pay attention to this and other variations in the constitution of the brachial plexus in the clinic and surgical procedures to avoid complications.