Anatomy, Head and Neck, Submental Triangle

The submental triangle, which is also known as the suprahyoid triangle, is part of the anterior triangle of the neck. The submental triangle is an unpaired triangle located between the hyoid bone and the mandible and medial to the anterior bellies of the digastric muscles. The borders of the submental triangle are the right and left anterior bellies of the digastric muscles laterally, with the mylohyoid muscles forming the floor of the submental triangle. The submental triangle contains important structures helping in the diagnosis process; for instance, the size of the submental lymph nodes can serve as a good indicator to determine whether the metastasis is present or not.

The area between the hyoid bone and the mandible gets divided by the anterior belly of the digastric muscle into two triangles, which are the submental triangle and the submandibular triangle. An unpaired submental triangle has its borders by the anterior bellies of the digastric muscles. The submental tringle's apex at the chin and its base is the body of the hyoid bone. The mylohyoid muscles comprise the floor of the submental triangle. The submental triangle contains the submental lymph nodes, the mylohyoid nerve and veins drain into the anterior jugular vein.[1]

The anterior belly of the digastric muscle is attached to the digastric fossa and runs backward and downward to join the posterior belly of the digastric muscle. The joined tendon inserts into the body and the greater cornu of the hyoid bone. The space between the anterior belly of the digastric muscle and the posterior belly of the digastric muscle is the submandibular triangle. The space between the right anterior belly of the digastric muscle and the left anterior belly of the digastric muscle is the submental triangle.

The mylohyoid muscle is above the anterior belly of the digastric muscle. The mylohyoid muscle attaches to the mylohyoid line of the mandible and runs medially and downward to its insertion into the body of the hyoid bone. The right mylohyoid muscle and the left mylohyoid muscle are forming the floor of the submental triangle.

The anterior belly of the digastric muscle starts embryonic development in the fourth week of pregnancy from the first pharyngeal arch.[1]

The mylohyoid muscle begins embryonic development in the fourth week of pregnancy from the first pharyngeal arch.

The submental lymph nodes are between the anterior bellies of the digastric muscle. The submental lymph nodes drain the floor of the mouth and the central area of the lower lip and the apex of the tongue. The submental lymph nodes drain into the submandibular lymph nodes and the deep cervical group which eventually drain into jugular lymph trunk.

The submental artery is the largest artery of the cervical branches of the facial artery. This artery emerges just after the facial artery exits from the submandibular gland. The submental artery delivers vascular supply to the skin of the submental area and the muscles that border the submental triangle — it anastomoses with the inferior alveolar artery and the sublingual artery. The submental artery runs between the mylohyoid muscle and the mandible and runs either deep or superficial relative to the anterior belly of the digastric muscle.[2]

In some cases, there are communications of the mylohyoid nerve and the lingual nerve in the submental triangle. The mylohyoid nerve penetrates the mylohyoid muscle; then it runs parallel to the submental artery and the submental vein. The submental nerve runs beneath the submental artery and the submental vein.[3]