Level V contains the lymph nodes of the posterior triangle.

This would leave no posterior triangle.

The occipital triangle, the larger division of the posterior triangle, is bounded, in front, by the Sternocleidomastoideus; behind, by the Trapezius; below, by the Omohyoideus.

The triangular space in front of this muscle is called the anterior triangle of the neck; and that behind it, the posterior triangle of the neck.

They can be caused by stretching, diseases, and wounds to the lateral cervical region (posterior triangle) of the neck or the axilla.

The posterior triangle (or lateral cervical region) is a region of the neck.

The posterior triangle is crossed, about 2.5 cm above the clavicle, by the inferior belly of the omohyoid muscle, which divides the space into two triangles:

The external jugular vein's superficial location within the posterior triangle also makes it vulnerable to injury.

Posterior to it is the posterior triangle.

The inferior belly of the omohyoid divides the posterior triangle of the neck into an upper or occipital triangle and a lower or subclavian triangle.