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Sternothyroid muscle

The sternothyroid muscle is a slender, vertically oriented muscle located in the anterior neck region. As one of the infrahyoid muscles, it plays a key role in depressing the larynx during swallowing and speech. The sternothyroid is clinically significant in both anatomical dissection and radiological imaging, serving as an important landmark in neck surgeries and imaging studies.

Anatomy of Sternothyroid Muscle

Origin:

  • Posterior surface of the manubrium of the sternum

  • First costal cartilage

Insertion:

  • Oblique line of the thyroid cartilage

Function:

  • Depresses the larynx after it has been elevated during swallowing and vocalization

  • Stabilizes the position of the larynx and thyroid cartilage

Nerve Supply:

  • Ansa cervicalis (C1–C3), a branch of the cervical plexus

Artery Supply:

  • Superior thyroid artery (branch of the external carotid artery)

  • Inferior thyroid artery (branch of the thyrocervical trunk)

Vein Supply:

  • Superior thyroid vein (drains into the internal jugular vein)

  • Inferior thyroid vein (drains into the left brachiocephalic vein)

Imaging Appearance

MRI Appearance:

  • T1-weighted images:

    • The sternothyroid muscle appears as a structure of intermediate (isointense) signal relative to surrounding soft tissue.

  • T2-weighted images:

    • Typically, the muscle has a relatively low signal (hypointense) compared to surrounding fat and glandular tissue.

  • STIR (Short Tau Inversion Recovery):

    • The muscle shows low signal unless there is edema, inflammation, or pathology, which may appear hyperintense.

CT Appearance:

  • The sternothyroid muscle appears as a well-defined, homogenous soft tissue structure with similar attenuation to other neck muscles.

  • It is best visualized on axial images, lying medial and slightly anterior to the sternohyoid muscle and lateral to the thyroid gland.

MRI images

Sternothyroid muscle axial mri image

CT image

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