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Rectus capitis lateralis muscle

The Rectus Capitis Lateralis muscle is a small but significant muscle in the upper cervical region of the neck. It plays an important role in stabilizing and facilitating subtle lateral movements of the head, connecting the transverse process of the atlas (C1 vertebra) to the occipital bone. Its detailed anatomical relationships, vascular and nerve supply, and imaging appearance are crucial for radiologists, neurologists, and clinicians involved in head and neck evaluation.

Synonyms

  • Lateral rectus capitis muscle

  • Lateral head straight muscle (rarely used)

Function

  • Lateral flexion (side bending) of the head at the atlanto-occipital joint

  • Stabilizes the atlanto-occipital joint during head movements

Origin

  • Superior surface of the transverse process of the atlas (C1 vertebra)

Insertion

  • Inferior surface of the jugular process of the occipital bone

Nerve Supply

  • Ventral rami of the first and second cervical spinal nerves (C1, C2)

Artery Supply

  • Ascending pharyngeal artery (branch of the external carotid artery)

  • Muscular branches from the vertebral artery

Vein Supply

  • Drains into the venous plexus surrounding the vertebral artery

  • Connections with the deep cervical vein

MRI Appearance

  • T1-weighted images: The muscle appears as a low to intermediate signal intensity structure, well-defined, located lateral to the atlanto-occipital joint.

  • T2-weighted images: Similar to other skeletal muscles, shows intermediate signal intensity. Pathological conditions may increase signal (e.g., edema, inflammation).

  • STIR sequences: Muscle tissue appears with low to intermediate signal intensity; edema or inflammation within the muscle will appear hyperintense (bright).

CT Appearance

  • The Rectus Capitis Lateralis muscle is seen as a small, soft tissue structure lateral to the lateral mass of the atlas and adjacent to the occipital bone. It is best visualized in thin-section axial and coronal images. Muscle density is similar to other skeletal muscles; fat stranding or atrophy may be noted in pathological conditions.

MRI images

Rectus capitis lateralis muscle mri axial image -img-00000-00000