Anterior Scalene
Original Editor - Wendy Walker
Lead Editors - Kim Jackson, Wendy Walker, Chrysolite Jyothi Kommu, Admin, Evan Thomas, Vidya Acharya, WikiSysop and Milijana Delevic
Description
The anterior scalene, AKA scalenus anterior (scalenus anticus; Latin: musculus scalenus anterior) muscle is one of the lateral muscles of the neck, belonging to the scalene group. It is deeply placed, lying behind the Sternocleidomastoid.
It is located between the subclavian vein and the subclavian artery. The roots of the brachial plexus pass posterior to it. The phrenic nerve crosses its anterior surface.[1]
Origin
Anterior tubercles of the transverse processes of cervical vertebrae C3-C6 [2]
Insertion
By a narrow, flat tendon attaches into the scalene tubercle on the inner border of the first rib, and into the ridge on the upper surface of the rib in front of the subclavian groove.
Nerve Supply
Anterior branches of the cervical nerves C5-C7.
Blood Supply
Ascending cervical branch of the inferior thyroid artery.
Action and Function
Anterior scalene can perform individually or in synergistic group with other two scalenes (Middle and Posterior)[3][4]
- Bilateral contraction causes anterior flexion of the neck - flexors
- Ipsilateral contraction of the anterior scalene muscle primarily results in lateral flexion of the neck to the same side, rotation of the neck to the opposite side and elevation of the first rib during forced inspiration.
- Elevate the 1st rib at the sternocostal and costovertebral joints and are accessory muscles of respiration
Clinical Significance
Accessory muscles of respiration-The Scalene muscles help in elevation of the first and second ribs in increasing the intrathoracic volume. To aid in breathing, these muscles act as accessory muscles of respiration in patients with respiratory distress. The important clinical sign is the usage of accessory muscles in respiratory distress[2]
The anterior scalene can be involved in thoracic outlet syndrome. The muscle forms part of the scalene triangle through which the brachial plexus and subclavian artery pass. Hypertrophy[5] or spasm of the anterior scalene can compress these structures, leading to neurological and vascular symptoms in the upper limb.
Referencest
- ↑ Harry WG, Bennett JD, Guha SC. Scalene muscles and the brachial plexus: anatomical variations and their clinical significance. Clinical Anatomy: The Official Journal of the American Association of Clinical Anatomists and the British Association of Clinical Anatomists. 1997;10(4):250-2.
- ↑ 2.0 2.1 Sam Bernes.The Scalene Muscles .Teach Me Anatomy.Accessed 28 April 2020.
- ↑ Kendall, McCreary, Provance: Muscle Testing and Function; Head and Neck Muscles; 4th Edition
- ↑ Muscolino; The Muscle and Bone Palpation Manual; Chapter 12; Palpation of Neck Muscales; Elsevier; 3rd Edition
- ↑ Farina R, Foti PV, Iannace FA, Conti A, Ferlito A, Conti A, Pennisi M, Santonocito S, Basile A. Thoracic outlet syndrome: a rare case with bilateral cervical ribs and bilateral anterior scalene hypertrophy. Journal of Ultrasound. 2021 Sep;24(3):331-6.