calculated. Three subdivisions of serratus anterior were identified. A new finding was the discovery of two distinctive fascicles attached to the superior and inferior aspects of rib 2.The rib 2 inferior fascicle had the largest PCSA (mean 1.6 cm 2 ) and attached, with the rib 3 fascicle, along the medial border of scapula to form the middle division. The rib 2 superior and rib 1 fascicles attached to the superior angle of scapula (upper division).Fascicles from ribs 4 to 8/9 attached to the inferior angle of scapula (lower division).Mean fascicle angle relative to a vertical midline reference and PCSA for each division were 29 o and 1.3 cm 2 (upper), 90 o and 2.2 cm 2 (middle), and 59 o and 3.0 cm 2 (lower).This novel study demonstrated the presence of morphologically distinct serratus anterior subdivisions. The results of this study will inform the development of optimal techniques for the assessment, treatment and rehabilitation of this architecturally complex muscle in shoulder and neck pain.