Boundaries:

• Inferior border of the mandible superiorly
• Medial border of the sternocleidomastoid laterally
• Midline of the neck medially

Contents:

• Muscles (platysma, mylohyoid, digastric, infrahyoids)
• Nerves and vessels
• Organs

Subdivisions:

• The submental triangle
• The submandibular triangle
• The carotid triangle
• The muscular triangle.

Boundaries:

• Midline medially
• Hyoid bone inferiorly
• Anterior belly of diagastric laterally.

Contains the submental gland.

Boundaries:

• Midline of the neck medially
• Superior belly of the omohyoid
• Sternocleidomastoid inferiorly

Contains the strap muscles.

Boundaries:

• Anterior belly of the digastric muscle medially
• Posterior belly of the digastric muscle laterally
• Mandible superiorly

Contains submandibular gland, facial artery and facial vein.

Boundaries:

• Digastric muscle superiorly
• Superior belly of the omohyoid medially
• Sternocleidomastoid laterally

Contains the carotid vessels.