What are the boundaries of Anterior Triangle of neck?

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Anterior triangle of neck is a large triangular region located on the side on the neck anterior to the sternocleidomastoid muscle. Its apex is directed downwards and base upwards. Its boundaries are:

• Anteriorly: Anterior median line of the neck.
• Posteriorly: Anterior border of sternocleidomastoid muscle.
• Base: Lower border of the mandible and a line extending from the angle of mandible to the mastoid process.
• Apex: Is the meeting point between anterior border of sternocleidomastoid and anterior median line.
• Roof: Investing layer of deep  cervical fascia.

 What are the subdivisions of Anterior Triangle of neck?

The anterior triangle on each side is subdivided into 3 and 1/2 triangles by the anterior and posterior bellies of digastric muscle and superior belly of omohyoid muscle. The subdivisions are as follows:

• Submental triangle (half only, because there is only one submental triangle)
• Digastric (submandibular) triangle
• Carotid triangle
• Muscular triangle

 What are the boundaries and contents of Submental Triangle?

It is a median triangle, therefore it occupies the upper part of both the anterior triangles. It lies below the chin and above the hyoid bone. Its boundaries are:

• On each side are the anterior bellies of digastric muscle.
• Base is formed by the body of hyoid bone.
• Apex is at symphysis menti.
• Floor is formed by mylohyoid muscles of both sides inserting into the median fibrous raphe (extending from symphysis menti to the hyoid bone).
• Roof is formed by investing layer of deep cervical fascia.

Contents of submental triangle are:

• Submental lymph nodes.
• Begining of anterior jugular veins.

The contents are located in the superficial fascia of submental triangle.

 What are the boundaries and contents of Muscular Triangle?

The boundaries of muscular triangle are as follows:

• Anteriorly: Anterior median line of the neck, extending from hyoid bone to the suprasternal notch.
• Posterosuperiorly: Superior belly of the omohyoid. 
• Posteroinferior: Anterior border of sternocleidomastoid.
• Floor is formed by sternothyroid, sternohyoid and thyrohyoid muscles.
• Roof is formed by investing layer of deep cervical fascia. 

Contents: It contains no significant structure, beneath its floor lie thyroid gland, trachea and oesophagus.

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