The base of each anterior triangle is the inferior margin of the mandible, the anterior margin is the midline of the neck, and the posterior margin is the anterior border of the sternocleidomastoid muscle. The apex of each anterior triangle points inferiorly and is at the suprasternal notch.
The anterior triangles are associated with structures such as the airway and digestive tract, and nerves and vessels that pass between the thorax and head. They are also associated with the thyroid and parathyroid glands.