Triangles of the Neck

Posterior Triangle of the Neck

Boundaries
Trapezius muscle
Sternocleidomastoid
Middle third of tje clavicle

Roof:
Investing layer of deep cervical fascia

Floor:
Splenius
Levator scapulae
Scalenus medius
Scalenus anterior and first digitation of Serratus anterior may contribute to the floor.
At the apex Semispinalis might appear


Contents

Artery
Subclavian artery

Nerves
Trunks of the brachial plexus
Branches of cervical plexus

The above-mentioned contents are covered by prevertebral fascia
Note that a surgoen wont cause injury to these structures if he does not breach the overlying prevertebral fascia.

Accessory nerve (CNXI)

Lymph nodes
Occipital (2 or 3 in number)
Supraclavicular

Muscle
Inferior belly of omohyoid