Posterior triangle of the neck

The posterior triangle of the neck forms the posterior compartment of the neck and is separated from the anterior triangle by the sternocleidomastoid muscle. The triangles of the neck are surgically focused, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spaces of the neck).

Boundaries

• anterior: posterior border of sternocleidomastoid
• posterior: anterior border of trapezius
• inferior: middle third of the clavicle
• roof: skin, superficial fascia and the investing layer of deep cervical fascia
• floor: prevertebral fascia overlying splenius capitis, semispinalis capitis, levator scapulae, scalenus medius and scalenus anterior

The inferior belly of the omohyoid that crosses the triangle divides it into an inferior supraclavicular and superior occipital triangles. 

Contents

The posterior triangle contains level 5 lymph node chains. These include spinal accessory and transverse cervical nodes. Depending on the location of the nodes above or below the accessory nerve, they are sub grouped as level 5a (above) or level 5b (below).