Proximal Attachment
It arises by tendinous slips from the transverse processes of C1 and C2 and the posterior tubercles of the transverse processes of C3 and C4 behind the attachment of scalenus medius.

Distal Attachment
It passes infero-laterally to attach to the medial border of the scapula between the superior angle and the triangular smooth area at the base of the scapular spine.  The lower part of the scapular attachment is enclosed by rhomboideus minor.