Scalenus anterior muscle

Changed by Craig Hacking, 15 Nov 2016

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The scalenus anterior (also known as anterior scalene) is a neck muscle and known as the "key" structure for the thoracic inlet as it is an important anatomical landmark.

Summary

origin: transverse processes of 3^rd to 6^th cervical vertebrae
insertion: inner border of first rib (scalene tubercle)
blood supply: ascending cervical artery
innervation: ventral rami of cervical nerves (C4, C5 and C6) from the cervical plexus and occasionally C3
action
- raises first rib (inspiration)
- adjunct: neck rotation/flexion
note: this muscle is covered by prevertebral fascia

Gross anatomy

Relations

anteriorly
- phrenic nerve, vagus nerve
- ascending cervical artery, transverse cervical artery, suprascapular artery
- internal jugular vein, subclavian vein
- sternocleidomastoid muscle, omohyoid muscle
- clavicle
posteriorly
- second portion of subclavian artery (which is divided in three parts by the muscle)
medially
- common carotid artery, first portion of subclavian artery, vertebral artery and vein
- stellate ganglion
- thoracic duct (left) or right lymphatic duct (right)
laterally
- brachial plexus
- third portion of subclavian artery

~~-insertion: inner border of first rib (scalene tubercle)</li>~~
+insertion: inner border of <a title="First rib" href="/articles/first-rib">first rib </a>(scalene tubercle)</li>
~~-blood supply: ascending cervical artery</li>~~
+blood supply: <a title="Ascending cervical artery" href="/articles/ascending-cervical-artery">ascending cervical artery</a>
+</li>
~~-<li>note: this muscle is covered by prevertebral fascia</li>~~
+<li>note: this muscle is covered by <a title="prevertebral fascia" href="/articles/prevertebral-fascia">prevertebral fascia</a>
+</li>
~~-<li>ascending cervical artery, transverse cervical artery, suprascapular artery</li>~~
+<li>
+<a href="/articles/ascending-cervical-artery">ascending cervical artery</a>, <a href="/articles/transverse-cervical-artery">transverse cervical artery</a>, <a href="/articles/suprascapular-artery">suprascapular artery</a>
+</li>
~~-<li>stellate ganglion</li>~~
+<li><a href="/articles/stellate-ganglion">stellate ganglion</a></li>
~~-<a href="/articles/thoracic-duct">thoracic duct</a> (left) or right lymphatic duct (right)</li>~~
+<a href="/articles/thoracic-duct">thoracic duct</a> (left) or <a href="/articles/right-lymphatic-duct">right lymphatic duct</a> (right)</li>