Scalene Muscles

The scalene muscles are comprised of the scalenus anterior, the scalenus medius, and the scalenus posterior.

Scalenus Anterior

Origin: Anterior tubercles of the  transverse processes of (C3-C6)
Insertion: Scalene tubercle and cranial crest of first rib
Action: Flexion of the cervical spine, Lateral flexion of the cervical spine,
Innervation: Ventral rami of (C3-C8)
Blood Supply: Branches of the cervical artery

Primary Actions of the Scalenus Anterior:

1. Flexion of the cervical spine when acting bilaterally

  Agonists:

  • Longus Colli
  • Scalenus Medius

  Antagonists:

  • Longissimus Cervicis
  • Iliocostalis Cervicis
  • Spinalis Cervicis
  • Splenius Cervicis
  • Semispinalis Cervicis

2. Lateral Flexion of the cervical spine when acting unilaterally

  Agonists:

  • Scalenus Medius
  • Scalenus Posterior
  • Iliocostalis cervicis
  • Splenius Cervicis,
  • Semispinalis Cervicis

  Antagonists:

  • Scalenus Anterior,
  • Scalenus Posterior
  • Iliocostalis Cervicis
  • Splenius Cervicis
  • Semispinalis Cervicis on opposite side

Secondary Actions of the Scalenus Anterior:

1. Assists with contralateral rotation of the cervical spine when acting unilaterally

  Agonists:

  • Semispinalis Cervicis
  • Multifidus,

  Antagonists: Same muscles opposite side

  • Semispinalis Cervicis
  • Multifidus

2. Assists with forced inspiration by elevating first rib

  Agonists:

  • Serratus Posterior Superior
  • Levatores Costarum Brevis
  • Levatores Costarum Longi

  Antagonist:

  • Serratus Posterior Inferior
  • Transversus Abdominis
Anterior Scalene

Scalenus Medius

Origin: Posterior tubercles of the transverse processes of (C2-C7)
Insertion: Cranial surface of the first rib
Action: Flexion of the cervical spine, Lateral flexion of cervical spine
Innervation: Ventral rami of (C3-C8)
Blood Supply: Branches of the cervical artery

Primary Actions of the Scalenus Medius:

1. Flexion of the cervical spine when acting bilaterally

  Agonists:

  • Longus Colli
  • Scalenus Anterior

  Antagonists:

  • Longissimus Cervicis
  • Iliocostalis Cervicis
  • Spinalis Cervicis
  • Splenius Cervicis
  • Semispinalis Cervicis

2. Lateral flexion of the cervical spine when acting unilaterally

  Agonists:

  • Scalenus Anterior
  • Scalenus Posterior
  • Iliocostalis Cervicis
  • Splenius Cervicis
  • Semispinalis Cervicis

  Antagonists: Same muscles on opposite side

  • Scalenus Anterior
  • Scalenus Posterior
  • Iliocostalis Cervicis
  • Splenius Cervicis
  • Semispinalis Cervicis

Secondary Actions of the Scalenus Medius:

1. Assists with contralateral rotation of the cervical spine when acting unilaterally

  Agonists:

  • Semispinalis Cervicis
  • Multifidus

  Antagonists: Same muscles on opposite side

  • Semispinalis Cervicis
  • Multifidus

2. Assists with forced inspiration by elevating the first rib

  Agonists:

  • Serratus Posterior Superior
  • Levatores Costarum Breves
  • Levatores Costarum Longi

  Antagonists:

  • Serratus Posterior Inferior
  • Transversus Abdominis
Middle Scalene Muscle

Scalenus Posterior

Origin: By tendons from the posterior tubercles of  the transverse processes of (C4–C6)
Insertion: Outer surface of 2nd rib
Action: Lateral flexion of the neck
Innervation: Ventral rami of (C3-C8)
Blood Supply: Branches of the cervical artery

Primary Actions of the Scalenus Posterior:

1. Lateral flexion of the cervical spine when acting unilaterally

  Agonists:

  • Scalenus Anterior
  • Scalenus Medius
  • Iliocostalis Cervicis
  • Splenius Cervicis,
  • Semispinalis Cervicis

  Antagonists: Same muscles on opposite side

  • Scalenus Anterior
  • Scalenus Medius,
  • Iliocostalis Cervicis
  • Splenius Cervicis
  • Semispinalis Cervicis

Secondary Actions of the Scalenus Posterior:

2. Assists with forced inspiration by elevating the second rib

  Agonists:

  • Serratus Posterior Superior
  • Levatores Costarum Breves,
  • Levatores Costarum Longi

  Antagonists: None

Posterior Scalene Muscle

For pain and symptoms information see: Scalenes Muscles Pain and Symptoms

Advertisement


Leave a Comment