The middle scalene (also middle scalene muscle, latin: musculus scalenus medius) is a muscle situated between the anterior and posterior scalene muscles in the lateral part of the neck. It is the largest and longest of the scalene muscles.
The middle scalene originates from the anterior tubercles of the transverse processes of the 2nd to 7th cervical vertebrae (C2 - C7).
The middle scalene inserts onto the upper surface of the first rib between the scalene tubercle and the subclavian groove.
By contracting on both sides the middle scalene flexes the neck forward. By contracting on one side it bends the neck laterally.
The middle scalene is innervated by the anterior rami of the 3rd to 7th cervical spinal nerves (C3 - C7).