Scalenus anterior muscle

The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the anterior scalene, middle scalene, and posterior scalene. They are innervated by the fourth, fifth, and sixth cervical spinal nerves (C4-C6). The anterior and middle scalene muscles lift the first rib and bend the neck to the same side; the posterior scalene lifts the second rib and tilts the neck to the same side. The muscles are named from Ancient Greek σκαληνός (skalenos), meaning 'uneven'. The scalene muscles originate from the transverse processes from the cervical vertebrae of C2 to C7 and insert onto the first and second ribs. The anterior scalene muscle (Latin: scalenus anterior), lies deeply at the side of the neck, behind the sternocleidomastoid muscle. It arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae, and descending, almost vertically, is inserted by a narrow, flat tendon into the scalene tubercle on the inner border of the first rib, and into the ridge on the upper surface of the second rib in front of the subclavian groove. It is supplied by the anterior ramus of cervical nerve 5 and 6. The middle scalene, (Latin: scalenus medius), is the largest and longest of the three scalene muscles. The middle scalene arises from the posterior tubercles of the transverse processes of the lower six cervical vertebrae. It descends along the side of the vertebral column to insert by a broad attachment into the upper surface of the first rib, posterior to the subclavian groove. The brachial plexus and the subclavian artery pass anterior to it. The posterior scalene, (Latin: scalenus posterior) is the smallest and most deeply seated of the scalene muscles. It arises, by two or three separate tendons, from the posterior tubercles of the transverse processes of the lower two or three cervical vertebrae, and is inserted by a thin tendon into the outer surface of the second rib, behind the attachment of the anterior scalene. It is supplied by cervical nerves C6, C7 and C8. It is occasionally blended with the middle scalene.