Neck Triangles: Anterior and Posterior

• The presentation provides an introduction to the neck triangles.
• The presenter is Dr. Ramya Rathan, Assistant Professor of Anatomy.
• The presentation took place on February 27, 2025.

Learning Objectives

• The learning objective is to identify the boundaries of the anterior which includes the carotid, submandibular, submental, muscular and posterior triangles.

General Information

• The neck is the area between the base of the skull, the inferior border of the mandible, and the superior thoracic aperture.
• The anterior portion of the neck contains major visceral structures located between the head and the thorax.
• These structures include the pharynx, larynx, trachea, esophagus, the thyroid, and parathyroid glands.
• The neck is divided into two triangles for descriptive purposes, separated by the sternocleidomastoid muscle.
• The two neck triangles are the anterior and posterior triangles.
• The skin is the most superficial structure covering the neck.

Posterior Triangle: Boundaries

• The anterior boundary: sternocleidomastoid.
• The posterior boundary: trapezius.
• The base: clavicle.
• The apex: where the anterior and posterior borders meet.
• The roof: Skin + Fascia + Platysma + investing layer of deep fascia.
• The omohyoid subdivides the posterior triangle into 2 triangles: the omoclavicular (also called the supraclavicular triangle) and the occipital triangle.

Anterior Triangle: Boundaries

• Anterior boundary: median line.
• Posterior boundary: sternocleidomastoid.
• Base: lower border of the mandible + line from the angle of the mandible to the mastoid process.
• Apex: suprasternal notch.
• Roof includes: Skin + Fascia + Platysma + investing layer as well as the facial nerve and cutaneous nerves.
• The omohyoid and digastric muscles subdivide the anterior triangle into submental, submandibular, carotid, and muscular triangles, using the hyoid as a keystone.
• All triangles within the anterior triangle are paired, except for the submental triangle, which spans both sides of the neck.
• The hyoid bone divides the anterior triangle into two areas: suprahyoid and infrahyoid regions.
• The suprahyoid region contains 4 muscles: mylohyoid, digastric, stylohyoid, and geniohyoid.
• The infrahyoid region contains 4 muscles commonly called strap muscles: omohyoid, sternohyoid, sternothyroid, and thyrohyoid.

Carotid Triangle

• The borders are:
• Anterosuperior border: Posterior belly of digastric and stylohyoid muscle.
• Anterioinferior border: Superior belly of Omohyoid.
• Posterior border: Anterior border of sternocleidomastoid muscle.

Submandibular/Digastric Triangle

• Above: the lower border of the Mandible, line joining the angle of the mandible to the mastoid process is a boundary.
• Below and behind: post belly of digastric and Stylohyoid muscle.
• Below and in front: Digastric muscle-anterior belly.
• Floor: Mylohyoid, Hyoglossus & Middle constrictor.

Muscular Triangle

• In front is a boundary: Median line of the neck from the hyoid bone to the suprasternal notch.
• Behind and above boundary: Superior belly of Omohyoid
• Behind and below boundary: Anterior border of sternocleidomastoid

Submental Triangle

• Borders:
• Apex at the Menti Symphysis.
• At the base: Hyoid bone
• Sides: Digastric- anterior belly
• Floor: Mylohyoid

Dr. Ramya Rathan introduces the neck triangles, focusing on identifying the boundaries of the anterior and posterior triangles, including the carotid, submandibular, submental, and muscular triangles. The neck is divided into anterior and posterior triangles by the sternocleidomastoid muscle.