The scalene muscles
are a group of three pairs of muscles
in the lateral neck
, namely the scalenus anterior
, scalenus medius
, and scalenus posterior
They are innervated by the spinal nerves C3-C8.
Origin and insertion
They originate from the transverse processes
from the cervical vertebrae
of CII to CVII and insert onto the first and second ribs
. Thus they are called the lateral vertebral muscles
The action of the anterior and middle scalene muscles is to elevate the first rib
and rotate the neck
to the same side; the action of the posterior scalene is to elevate the second rib and tilt the neck to the same side.
They also act as accessory muscles of inspiration, along with the sternocleidomastoids.
The scalene muscles have an important relationship to other structures in the neck. The brachial plexus
and subclavian artery
pass between the anterior and middle scalenes. The subclavian vein
nerve pass anteriorly to the anterior scalene as it crosses over the first rib.
The passing of the brachial plexus and the subclavian artery through the space of the anterior and middle scalene muscles constitute the scalene hiatus (the term "scalene fissure" is also used). The region in which this lies is referred to as the scaleotracheal fossa. It is bound by the clavicle inferior anteriorly, the trachea medially, posteriorly by the trapezius, and anteriorly by the platysma muscle.
The origin of the scalenes is 1st and 2nd ribs
The insertion is the transverse processes of c2-c7.