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Semispinalis cervicis muscle

The semispinalis cervicis is a deep intrinsic muscle of the back and neck, forming part of the transversospinalis group. It plays a crucial role in extending and rotating the cervical spine. Located deep to the semispinalis capitis, the muscle spans from the upper thoracic vertebrae to the cervical vertebrae, providing postural support and contributing to neck movement and stability.

Anatomical Points:

Function:

  • Extension of the cervical spine (bilateral contraction)

  • Rotation of the cervical spine to the opposite side (unilateral contraction)

  • Assists in maintaining posture and stabilizing the cervical vertebrae

Origin:

  • Transverse processes of the T1 to T6 vertebrae

Insertion:

  • Spinous processes of the C2 (axis) to C5 vertebrae

Nerve Supply:

  • Dorsal rami of the cervical and upper thoracic spinal nerves (typically C3–T6)

Artery Supply:

  • Deep cervical artery

  • Occipital artery

  • Dorsal branches of the posterior intercostal arteries

Vein Supply:

  • Corresponding veins follow the arterial supply:

    • Deep cervical vein

    • Occipital vein

    • Posterior intercostal veins

Imaging Appearance:

MRI Appearance:

  • T1-weighted:

    • Semispinalis cervicis appears as a muscle with intermediate signal intensity (similar 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):

    • Markedly hyperintense in areas of edema, inflammation, or injury; normal muscle is relatively hypointense

CT Appearance:

  • Appears as a soft tissue structure posterior and lateral to the cervical spinous processes

  • Normal muscle density; clear muscle margins in high-resolution CT

MRI images

Semispinalis cervicis muscle mri axial image