[1] At first, it passes downward and laterally across the scalenus anterior and phrenic nerve, being covered by the sternocleidomastoid muscle; it then crosses the subclavian artery and the brachial plexus, running behind and parallel with the clavicle and subclavius muscle and beneath the inferior belly of the omohyoid to the superior border of the scapula.

It travels close to the bone, running through the suprascapular canal underneath the supraspinatus muscle,[4] to which it supplies branches.

It then descends behind the neck of the scapula, through the great scapular notch and under cover of the inferior transverse ligament, to reach the infraspinatous fossa, where it supplies infraspinatus[5] and anastomoses with the scapular circumflex artery and the descending branch (aka dorsal scapular artery) of the transverse cervical artery.

Besides distributing branches to the sternocleidomastoid (which, however, mainly is supplied by the occipital artery and the superior thyroid artery), subclavius (which mainly is supplied by the thoracoacromial artery), and neighboring muscles, it gives off a suprasternal branch, which crosses over the sternal end of the clavicle to the skin of the upper part of the chest; and an acromial branch, which pierces the trapezius and supplies the skin over the acromion, anastomosing with the thoracoacromial artery.

This article incorporates text in the public domain from page 582 of the 20th edition of Gray's Anatomy (1918) ocular group: central retinal