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Subclavius muscle

The subclavius muscle is a small, triangular muscle located beneath the clavicle (collarbone), forming part of the anterior wall of the axilla. Though relatively minor compared to other shoulder muscles, it plays an important role in stabilizing the clavicle during shoulder and arm movements. Clinically, its anatomical and imaging features are relevant in trauma, thoracic outlet syndrome, and clavicular fractures.

Origin:

  • First rib at the junction between the rib and its costal cartilage

Insertion:

  • Inferior surface of the middle third of the clavicle (subclavian groove)

Function:

  • Depresses the clavicle

  • Draws the clavicle anteriorly and inferiorly

  • Stabilizes the clavicle during movements of the shoulder girdle

  • Offers some protection to the underlying neurovascular bundle (subclavian vessels and brachial plexus) in case of clavicular fractures

Nerve Supply:

  • Nerve to subclavius (C5, C6), a small branch of the upper trunk of the brachial plexus

Artery Supply:

  • Clavicular branch of the thoracoacromial artery

  • Sometimes receives small branches from the suprascapular and subclavian arteries

Vein Supply:

  • Drained by veins accompanying the thoracoacromial artery, which empty into the axillary and subclavian veins

MRI Appearance:

  • T1-weighted:
    The subclavius muscle appears as an intermediate-to-low signal intensity structure (isointense to other skeletal muscles) beneath the clavicle.

  • T2-weighted:
    Normally, the subclavius muscle shows low signal intensity similar to other muscles. Edema or injury may appear hyperintense.

  • STIR (Short Tau Inversion Recovery):
    The muscle is usually of low signal unless inflamed or injured, where it demonstrates high (bright) signal intensity due to fluid/edema.

CT Appearance:

  • The subclavius muscle appears as a small, soft tissue density under the clavicle, distinguishable from surrounding fat and neurovascular structures. It is best visualized in axial and coronal planes, especially in trauma or thoracic outlet imaging.

MRI images

Subclavius muscle mri axial image

CT image

Subclavius muscle anatomy CT axial image -img-00000-00000

CT image

Subclavius muscle ct sag

CT image

Subclavius muscle ct

MRI image

Subclavius muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000