Blood Vessels of Head and Neck

The neck is considered to be quadrangular. This shape is the basis to study various components of the neck and their relations. The boundaries of the quadrangular shape include the mandible, upper border of the clavicle, midline of the neck, and anterior margin of the trapezius. The quadrangular shape is divided into an anterior and posterior triangle by the sternocleidomastoid muscle (SCM). The anterior and posterior triangles are the 2 primary subdivisions and are delineated by easily recognized anatomic structures. Each triangle houses muscles, nerves, vasculature, lymphatics, and adipose tissue.

Blood supply to the brain can be divided into an anterior and a posterior circulation, which interconnect to form the circle of Willis. The anterior circulation is derived from the internal carotid arteries and consists mainly of the anterior and middle cerebral arteries. The posterior circulation is derived from the vertebral arteries and consists primarily of the cerebellar and posterior cerebral arteries. The primary venous drainage of the brain occurs via the internal jugular vein.