Sometimes the subclavian vein passes with the artery behind the Scalenus anterior.

These structures are entrapped between the cervical rib and scalenus muscle.

The phrenic nerve is then isolated under the scalenus anticus muscle.

It is occasionally blended with the scalenus medius.

Behind the posterior groove is a rough area for the attachment of the Scalenus medius.

It projects outward medially and is the site of insertion for scalenus anterior.

The subclavian vein lies below and in front of the artery, separated from it by the Scalenus anterior.

This is in contrast to the subclavian vein, which travels anterior to the scalenus anterior.

The first portion extends from the origin of the vessel to the medial border of the Scalenus anterior.

Occasionally, it perforates the Scalenus anterior; more rarely it passes in front of that muscle.

It is bounded in front by the scalenus medius and behind by splenius cervicis.

The roots from C5 and C6 pierce the scalenus medius, while the C7 root passes in front of the muscle.

The Scalenus medius, also known as the middle scalene, is the largest and longest of the three scalene muscles in the human neck.

The first part runs upward and backward between the Longus colli and the Scalenus anterior.

Behind, it lies on the lowest trunk of the brachial plexus, which intervenes between it and the Scalenus medius.

Behind the vessel are the pleura and the Scalenus medius; above, the brachial plexus of nerves; below, the pleura.

Scalenus: originates on the cranial and lateral side of the first rib, inserts into the transverse process of the cervical vertebrae (C4-C7).

The second portion of the subclavian artery lies behind the Scalenus anterior; it is very short, and forms the highest part of the arch described by the vessel.

Scalenus anticus syndrome (compression on brachial plexus and/or subclavian artery caused by muscle growth) - diagnosed by using Adson's sign with patient's head turned outward.

The suprascapular artery and transverse cervical artery both head laterally and cross in front of (anterior to) the scalenus anterior muscle and the phrenic nerve.

The Scalenus anterior (scalenus anticus), also known as anterior scalene muscle, lies deeply at the side of the neck, behind the Sternocleidomastoideus.

The costocervical trunk arises from the upper and back part of the subclavian artery, behind the scalenus anterior on the right side, and medial to that muscle on the left side.

The third portion of the subclavian artery runs downward and lateralward from the lateral margin of the Scalenus anterior to the outer border of the first rib, where it becomes the axillary artery.

The thyrocervical trunk is a branch of the subclavian artery arising from the first portion of this vessel, i.e. between the origin of the subclavian artery and the inner border of the scalenus anterior muscle.

The first part of the right subclavian artery arises from the innominate artery, behind the upper part of the right sternoclavicular articulation, and passes upward and lateralward to the medial margin of the Scalenus anterior.