Proximal Attachment
Scalenus anterior arises by musculotendinous fascicles from the anterior tubercles of the transverse processes of C3 to C6.  These attachments are separated from those of longus capitis by the ascending cervical branch of the inferior thyroid artery.

Distal Attachment
The fascicles converge as they descend almost vertically to attach by a narrow flat tendon to the scalene tubercle on the inner border of the first rib and a ridge on the upper surface of the rib, anterior to the groove for the subclavian artery.