Anteriorly	Anteromedian line of the neck
Posteriorly	Anterior border of the .sternocleidomastoid muscle
Superiorly	Inferior border of mandible
Apex	Jugular notch

Subdivisions

• Digastric triangle (1)
• Carotid triangle (2)
• Muscular triangle (3)
• Submental triangle (4)

Boundaries

Contents

1) Infrahyoid muscles (strap muscles).

•  Sternohyoid

•  Sternothyroid

•  Thyrohyoid

•  Omohyoid* forming part of the boundary.

Note

• These muscles are innervated by ansa cervicalis (c1-c3) except thyrohyoid that is innervated by C1 via Hypoglossal nerve. They depress the hyoid bone and larynx during swallowing and speaking, anchoring it in position
  

2) The anterior jugular veins, run in both sides of the midline. They are joined by the jugular arch at the suprasternal notch.

Identify the structures labelled 4-6