Two cord stage in the infraclavicular part of the brachial plexus

Variations of the brachial plexus occurs in the formation of trunks, divisions, and cords; in the origin and/or combination of branches; and in the relationship to the axillary artery and scalene muscles, however the make up of the terminal branches (components of the nerves) is unchanged [1]. The three cords of brachial plexus enter the axilla and are arranged according to their names around the second and third part of axillary artery. But in the first part of axillary artery, the relations are different; the lateral and posterior cords lie lateral to the axillary artery, where as the medial cord lies behind the axillary artery [2]. The three trunks of the brachial plexus incline laterally, and either just above or behind the clavicle each bifurcates into anterior and posterior divisions. The anterior divisions of the upper and middle trunks form a lateral cord that lies lateral to the axillary artery. The anterior division of the lower trunk descends at first behind and then medial to the axillary artery and forms the medial cord, posterior divisions of all three trunks form the posterior cord, which is at first above and then behind the axillary artery [2]. Here a rare variation of two cord stage of the infraclavicular part of the brachial plexus representing anterior and posterior cords situated lateral to the axillary artery is reported. The clinical implications of this finding are discussed. Jamuna M Amudha G