Middle Scalene
Original Editor - Wendy Walker
Lead Editors - Wendy Walker, Kim Jackson, Milijana Delevic, Admin, WikiSysop, Wendy Snyders and Evan Thomas
Description[edit | edit source]
Middle scalene or scalenus medius (Latin: musculus scalenus medius), is the largest and longest muscle in the scalene group of lateral neck muscles.[1] Often penetrated by the dorsal scapular[1] and long thoracic nerves[2], it is deeply placed, lying behind sternocleidomastoid[2].
Origin[edit | edit source]
Insertion[edit | edit source]
The tendon inserts onto the superior border of the 1st rib, anterior to the 1st rib's tubercle and posterior to the subclavian groove.[1][2][3].Insertion variations include insertion onto the 2nd rib[4][2].
Nerve Supply[edit | edit source]
Anterior rami of cervical spinal nerves C3 - C8 [1][2][3].
Blood Supply[edit | edit source]
The ascending cervical artery branch of the inferior thyroid artery supplies the middle scalene[2][3][1].
Action and Function[edit | edit source]
The middle scalene work with the anterior scalene to elevate the first rib during respiration[1][3] and are also strong ipsilateral flexors during unilateral contraction[3][1]. The middle scalene are also involved with cervical rotation[3][2].
Clinical significance[edit | edit source]
The interscalene triangle (scalene triangle) is the anatomical triangle formed between the scalenus anterior muscle (anteriorly), the scalenus medius muscle (posteriorly) and the first rib (inferiorly)[1][4]. Structures including the subclavian artery and brachial plexus pass through it[1]. Abnormal anatomy or injury to this region can cause compression of the neurovascular structures leading to thoracic outlet syndrome (TOS)[2][4]. TOS typically leads to paraestheisa, pain and weakness in the ipsilateral upper limb[2]. Please see the page on TOS for more information regarding this syndrome.
References[edit | edit source]
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Kenhub 2022, Kenhub: scalene muscles, viewed 16/12/22,https://www.kenhub.com/en/library/anatomy/scalene-muscles
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Bordoni B, Varacallo M. Anatomy, head and neck, scalenus muscle. StatPearls [Internet]. 2022 Apr 16.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Anatomy.app 2022, Anatomy.app: Middle scalene, viewed 16/12/22,https://anatomy.app/encyclopedia/middle-scalene
- ↑ 4.0 4.1 4.2 4.3 Georgakopoulos B, Lasrado S. Anatomy, Head and Neck, Inter-scalene Triangle. InStatPearls [Internet] 2021 Nov 5. StatPearls Publishing.
