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Platysma muscle

The platysma muscle is a thin, superficial sheet of muscle located in the anterior aspect of the neck. It is part of the superficial musculoaponeurotic system and plays a crucial role in facial expression, particularly in conveying tension or stress. The platysma lies within the subcutaneous tissue and is easily identified due to its superficial location. Its thin, broad structure extends from the upper chest and shoulder region, ascending upward to the lower face, and is often visible when tensed. Understanding the anatomy and imaging characteristics of the platysma is vital in clinical practice, particularly for radiologists, surgeons, and those specializing in head and neck anatomy.

Synonyms

  • Platysma myoides

  • Subcutaneous muscle of the neck

Function

  • Tenses the skin of the neck

  • Depresses the lower jaw and the corners of the mouth

  • Assists in facial expressions such as frowning or expressions of tension

  • Protects underlying neurovascular structures

Origin

  • Fascia covering the superior parts of the pectoralis major and deltoid muscles (in the upper thoracic and shoulder regions)

Insertion

  • Inferior border of the mandible

  • Skin and subcutaneous tissue of the lower face and angle of the mouth

Nerve Supply

  • Cervical branch of the facial nerve (cranial nerve VII)

Artery Supply

  • Submental branch of the facial artery

  • Suprascapular artery (minor contribution)

Vein Supply

  • Facial vein

  • External jugular vein (via subcutaneous venous network)

MRI Appearance

  • T1-weighted images: Platysma muscle appears as a thin, hypointense (dark) structure relative to surrounding subcutaneous fat

  • T2-weighted images: Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology.

  • STIR (Short Tau Inversion Recovery): Muscle remains hypointense, with surrounding fat being suppressed for clearer delineation

CT Appearance

  • Appears as a thin, soft tissue density immediately deep to the subcutaneous fat layer in the anterior neck

  • Best visualized on axial images with soft tissue window settings

MRI images

Platysma muscle MRI AXIAL IMAGE