Sternocleidomastoid Region: The “No Man’s Land” in Neck

Sternocleidomastoid muscle is an important structure of the neck. This rhomboid shaped muscle lies obliquely in the neck, extending from manubrium sterni, and medial third of the clavicle antero-inferiorly to the mastoid process and occipital bone postero-superiorly. The muscle superficially crosses various vital structures in the neck such as trachea, oesophagus, common carotid artery, internal jugular vein, vagus nerve, symphathetic chain and jugular group of lymph nodes. It is supplied by the occipital and superior thyroid arteries and receives its nerve supply from 11th cranial (Spinal root of accessory) and 2nd & 3rd cervical (Proprioceptive and motor) nerves. Sternocleidomastoid muscle separates the two triangles in each half of the neck [1] (Figure 1). The Anterior Triangle is described as being bounded by mid line anteriorly, anterior border of sternocleidomastoid posteriorly and the lower border of mandible superiorly. The Posterior triangle is described as bounded by posterior border of sternocleidomastoid, anterior border of trapezius and middle third of clavicle inferiorly.