Submandibular Triangle

Rodrigo Arrangoiz MS, MD, FACS, FSSO
  • The submandibular triangle:
    • Is a subsection of the larger anterior triangle of the neck:
      • Which is defined by the following boundaries:
        • Lateral: 
          • Sternocleidomastoid muscle
        • Superior: 
          • Inferior border of the mandible
        • Medial: 
          • Anterior midline of the neck
  • The submandibular triangle, also known as digastric triangle:
    • Is located superior to the hyoid bone
    • It is bordered:
      • Superiorly by the inferior border of the mandible and the mastoid process
      • Posteriorly by the posterior belly of the diagastric and stylohoid muscles
      • Anteriorly by the anterior belly of digastric muscle
    • The roof of the triangle is formed by the:
      • Skin
      • Superficial cervical fascia
      • The platysma
      • Deep cervical fascia
    • The branches of the facial nerve and transverse cutaneous cervical nerves:
      • Also pass over the roof of the triangle
  • Digastric muscle:
    • The submandibular triangle is largely defined by the digastric muscle:
      • Which is a double-bellied muscle that depresses the mandible:
        • Opens the mouth
    • The anterior belly:
      • Arises from the digastric fossa found in the inner / internal aspect of the anterior mandible
    • The posterior belly:
      • Arises from the mastoid notch of temporal bone
    • Both are joined by a tendinous sheath:
      • Attach to the hyoid bone
  • A major landmark of the submandibular triangle:
    • Is the submandibular gland (innervated by the facial nerve):
      • This salivary gland can be described as having two lobes:
        • Which are divided by the posterior border of the mylohyoid muscle
      • The superificial lobe:
        • Is the larger of the two
        • Located superficial to the inferior surface of the mylohyoid muscle
      • The smaller deep lobe wraps around the posterior border of the mylohyoid
  • Contents of the submandibular triangle:
    • In terms of surgical practice, the submandibular triangle is best visualized as having four layers:
      • These layers start from the skin and continue progressively deeper
    • First layer (roof):
      • As previously mentioned, the roof of the submandibular triangle i.e. the first plane encountered surgically comprises of the skin and the superficial fascia:
        • These enclose the platysma muscle and the subcutaneous fat
        • Also enclosed are the cervical and mandibular branches of the facial nerve (cranial nerve VII)
    • Second layer (submandubilar space):
      • The second surgical plane of the submandibular triangle, the following contents can be found:
        • The submandibular lymph nodes
        • The superficial portion / lobe of the submandibular gland
        • The submental branch of the facial vein:
          • Which accompanies the submental branch of the facial artery
        • The vessels and nerves to mylohyoid muscle:
          • Lie directly along the inferior surface of the same muscle
        • The superficial / investing layer of the deep cervical fascia is also located here
      • Both the facial vein and anterior branch of the retromandibular vein:
        • Cross the triangle anterior, or superficial to the submandibular gland, and unite near to the angle of the mandible:
          • To form the common facial vein:
            • The common facial vein then drains into the internal jugular vein near the greater cornu of the hyoid bone
      • The facial artery (which is the fourth branch of the external carotid artery):
        • Also enters the submandibular triangle by passing beneath the posterior belly of the digastric muscle, as well as the stylohyoid muscle
        • Once it enters the triangle, it also lies deep to the submandibular gland
        • Once the artery has crossed the gland over its posterior aspect, it curls around the inferior border of the mandible, and ascends superomedially across the facial region
      • The inferior tip of the parotid gland can be found within in the posterior region of the digastric triangle
      • Ascending within the substance of the parotid gland is the external carotid artery
    • Third layer (floor):
      • Next is the third surgical layer
      • Once again the structures from superficial to deep are the:
        • Mylohyoid muscle along with its nerve
        • The hyoglossus muscle
        • As well as the middle pharyngeal constrictor muscle:
          • Which lies over the lower part of the superior pharyngeal constrictor, and a subsection of the styloglossus muscle
      • The mylohyoid muscles:
        • Are regarded as the true diaphragm of the floor of the mouth
        • These muscles arise from the mylohyoid line:
          • That is found on the inner surface of the mandible
        • Inserts into the body of the hyoid bone itself
        • The nerve that supplies the mylohyoid:
          • Is a branch of the alveolar division of the mandibular division of the trigeminal nerve (CN V3):
            • Lies on the surface of the inferior aspect of the muscle
        • The superior surface of mylohyoid is in contact with the lingual nerve (division of V3) and hypoglossal nerve (cranial nerve XII)
Mylohyoid Muscle
  • Fourth layer (basement / sublingual space)
    • Finally we have the deepest or fourth surgical plane
    • The structures within this plane, from superficial to deep are:
      • The deep portion of the submandibular gland
      • The duct of the submandibular gland (Wharton’s duct)
      • The lingual nerve (division of V3)
      • The sublingual artery & vein:
        • Which lie superficial to the sublingual gland
    • The submandibular duct is found inferior to the lingual nerve (except where the lingual nerve passes beneath it) as well as superior to the hypoglossal nerve
    • Deeper still we find cranial nerve XII (hypoglossal nerve), as well as the submandibular ganglion
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Published by Rodrigo Arrangoiz MS, MD, FACS, FSSO

My name is Rodrigo Arrangoiz I am a breast surgeon/ thyroid surgeon / parathyroid surgeon / head and neck surgeon / surgical oncologist that works at Center for Advanced Surgical Oncology in Miami, Florida. I was trained as a surgeon at Michigan State University from (2005 to 2010) where I was a chief resident in 2010. My surgical oncology and head and neck training was performed at the Fox Chase Cancer Center in Philadelphia from 2010 to 2012. At the same time I underwent a masters in science (Clinical research for health professionals) at the University of Drexel. Through the International Federation of Head and Neck Societies / Memorial Sloan Kettering Cancer Center I performed a two year head and neck surgery and oncology / endocrine fellowship that ended in 2016. Mi nombre es Rodrigo Arrangoiz, soy cirujano oncólogo / cirujano de tumores de cabeza y cuello / cirujano endocrino que trabaja Center for Advanced Surgical Oncology en Miami, Florida. Fui entrenado como cirujano en Michigan State University (2005 a 2010 ) donde fui jefe de residentes en 2010. Mi formación en oncología quirúrgica y e n tumores de cabeza y cuello se realizó en el Fox Chase Cancer Center en Filadelfia de 2010 a 2012. Al mismo tiempo, me sometí a una maestría en ciencias (investigación clínica para profesionales de la salud) en la Universidad de Drexel. A través de la Federación Internacional de Sociedades de Cabeza y Cuello / Memorial Sloan Kettering Cancer Center realicé una sub especialidad en cirugía de cabeza y cuello / cirugia endocrina de dos años que terminó en 2016.

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