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Longissimus capitis muscle

The Longissimus capitis is a key muscle of the deep layer of the intrinsic back muscles, specifically belonging to the erector spinae group. It runs longitudinally along the cervical and upper thoracic regions, contributing to the extension and lateral flexion of the head and neck. Understanding its anatomy, imaging appearance, and neurovascular supply is essential for clinicians interpreting radiological studies and managing related pathologies.

Synonyms

  • Longissimus dorsi capitis

  • Longissimus atlantis

  • Musculus longissimus capitis (Latin)

Function

  • Extension of the head and neck (bilateral contraction)

  • Lateral flexion and slight rotation of the head to the same side (unilateral contraction)

  • Provides postural support for the head and cervical spine

Origin

  • Transverse processes of T1–T5 (sometimes T3–T6) vertebrae

  • Articular processes of C4–C7 vertebrae

Insertion

  • Posterior margin of the mastoid process of the temporal bone

Nerve Supply

  • Posterior rami of the cervical and upper thoracic spinal nerves (primarily C3–C8)

Artery Supply

  • Branches from the occipital artery

  • Deep cervical artery

  • Muscular branches from the vertebral artery

Vein Supply

  • Occipital vein

  • Deep cervical vein

  • Vertebral venous plexus

MRI Appearance

  • T1-weighted images: Appears as intermediate to low signal intensity relative to fat, similar to other skeletal muscle.

  • T2-weighted images: Typically intermediate signal intensity, with surrounding fat appearing hyperintense.

  • STIR (Short Tau Inversion Recovery): Muscle is suppressed (low signal) except in cases of edema, trauma, or inflammation, which would appear hyperintense.

CT Appearance

  • On CT, the Longissimus capitis muscle shows soft tissue density similar to other skeletal muscles.

  • It is best visualized in axial sections as a paired, elongated muscle lateral to the cervical vertebrae, deep to the splenius capitis.

MRI images

Longissimus capitis muscle MRI AXIAL IMAGE