The posterior triangle of the neck is on the lateral aspect of the neck in direct continuity with the upper limb (Fig. 8.183). It is bordered: anteriorly by the posterior edge of the sternocleidomastoid muscle, posteriorly by the anterior edge of the trapezius muscle, basally by the middle one-third of the clavicle, and apically by the occipital bone just posterior to the mastoid process where the attachments of the trapezius and sternocleidomastoid come together.