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Trapezius muscle

The trapezius muscle is a large, superficial, triangular muscle covering the upper back and posterior neck. It plays a crucial role in the movement and stabilization of the scapula and extends from the occipital bone to the lower thoracic vertebrae, laterally attaching to the clavicle and scapula. The trapezius is vital in maintaining posture and facilitating various shoulder and neck movements. Its unique anatomical positioning and function make it a significant muscle in both clinical and imaging assessments.

Anatomy of Trapezius Muscle

Origin:

  • External occipital protuberance

  • Medial third of the superior nuchal line of the occipital bone

  • Nuchal ligament

  • Spinous processes of C7 to T12 vertebrae

Insertion:

  • Lateral third of the clavicle

  • Acromion process of the scapula

  • Spine of the scapula

Function:

  • Elevation of the scapula (upper fibers)

  • Retraction of the scapula (middle fibers)

  • Depression of the scapula (lower fibers)

  • Upward rotation of the scapula

  • Extension, lateral flexion, and rotation of the neck (upper fibers)

Nerve Supply:

  • Motor: Spinal accessory nerve (cranial nerve XI)

  • Sensory: Ventral rami of C3 and C4 (for proprioception and pain)

Artery Supply:

  • Transverse cervical artery (primary supply)

  • Dorsal scapular artery (contributes, especially to lower part)

  • Occipital artery (minor supply to upper part)

Vein Drainage:

  • Transverse cervical vein

  • Dorsal scapular vein

  • Occipital vein (minor drainage)

Imaging Appearance

MRI Appearance:

  • T1-weighted: Trapezius muscle shows intermediate (isointense) signal relative to other skeletal muscles.

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

  • STIR (Short Tau Inversion Recovery): Muscle is of low to intermediate signal; increased signal intensity indicates edema, inflammation, or injury.

CT Appearance:

  • The trapezius muscle is visualized as a well-defined, symmetrical, soft tissue density along the posterior aspect of the neck and upper thorax.

  • Muscle tissue appears homogeneously denser than surrounding fat, without enhancement unless pathology is present.

MRI images

Trapezius muscle MRI AXIAL IMAGE

MRI images

Trapezius muscle

CT images

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CT images

Trapezius muscle anatomy CT axial image -img-00000-00000_00001

MRI images

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MRI images

Trapezius muscle anatomy MRI coronal image -img-00000-00000

MRI images

Trapezius muscle sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT images

Trapezius muscle ct sag

CT images

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