The posterior triangle of the neck is created by the clavicle as the base, with the sternocleidomastoid + trapezius coming together to form the apex.
Its roof is the investing layer of deep cervical fascia.
Its floor is the prevertebral fascia covering the scalene muscles.
5 muscles, 4 arteries, 3 nerves and 2 veins.
4 arteries - 1 at the base, 1 at the apex and 2 transverse Arteries going Across.
3 nerves - A - accessory. B - Brachial Plexus. C - Cervical Plexus.