In front, it is covered by the skin, the superficial fascia, the platysma muscle, the deep cervical fascia, the sternocleidomastoid muscle, and the scalenus anterior muscle. On the right side of the neck, the phrenic nerve is separated from the second part of the artery by the scalenus anterior muscle, while on the left side it crosses the first part of the artery close to the medial edge of the muscle. Behind the artery are the pleura and the scalenus medius muscle. Above the artery is the brachial plexus. Below the artery is the pleura. The subclavian vein lies below and anterior to the artery, separated from it by the scalenus anterior muscle.