There are multiple possible causes of TOS, majority of which results in anatomic restrictions. These possible causes include trauma to the shoulder girdle and more commonly postural disturbances. Individuals with TOS often sit at a computer or desk for an extended period of time for work or school. They develop rounded shoulders and a forward head carriage which changes the length and tone of certain muscles and the relationship of structures in relation to the neurovascular bundle. The anatomic disturbances that contribute and is of the greatest interest to osteopathy includes hypertonicity of the anterior and middle scalene muscles in the neck, hypertonicity of the pectorialis muscle from the upper extremity to the 3-5th ribs, somatic dysfunctions of the clavicle, upper thoracic region and ribs (especially the first rib) (Ward, 2003).