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Stylohyoid muscle

The stylohyoid muscle is a slender, ribbon-like muscle located in the anterior triangle of the neck. It plays a crucial role in the mechanics of swallowing by elevating and retracting the hyoid bone. The muscle extends from the styloid process of the temporal bone to the hyoid bone, running parallel and just above the posterior belly of the digastric muscle. Understanding its anatomy, function, and imaging characteristics is important for clinical evaluation and surgical interventions in the neck region.

Anatomy and Description

  • The stylohyoid muscle is a thin, elongated muscle in the suprahyoid group of neck muscles.

  • It lies superficially in the neck, medial to the angle of the mandible, and is closely associated with the posterior belly of the digastric muscle.

  • It is separated from the pharyngeal constrictor muscles by connective tissue.

Function

  • Elevates and retracts the hyoid bone during swallowing.

  • Helps to elongate the floor of the mouth.

  • Assists in the stabilization of the hyoid bone.

Origin

  • Styloid process of the temporal bone.

Insertion

  • Body of the hyoid bone, at its junction with the greater horn.

  • The muscle typically splits to allow passage of the intermediate tendon of the digastric muscle before attaching to the hyoid bone.

Nerve Supply

  • Innervated by the facial nerve (cranial nerve VII), specifically its cervical branch.

Artery Supply

  • Supplied mainly by the branches of the facial artery.

  • Additional blood supply can come from the lingual artery.

Vein Supply

  • Drains into the common facial vein and, to a lesser extent, the lingual vein.

MRI Appearance

  • T1-weighted images:

    • The muscle appears isointense (intermediate signal intensity) compared to other skeletal muscles.

  • T2-weighted images:

    • Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology.

  • STIR (Short Tau Inversion Recovery):

    • Normal muscle shows low signal.

    • Any edema or pathology within the muscle will appear as high signal intensity on STIR images.

CT Appearance

  • The stylohyoid muscle appears as a soft tissue structure extending from the styloid process to the hyoid bone.

  • It can be visualized as a slender, elongated structure, best appreciated on contrast-enhanced scans.

MRI images

Stylohyoid muscle mri axial image