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Topic

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Transverse process of atlas

The transverse processes of the atlas (C1) are paired bony projections extending laterally from the lateral masses of the first cervical vertebra. Each transverse process serves as a lever for muscular and ligamentous attachments, including the levator scapulae, rectus capitis lateralis, and intertransversarii muscles, and provides a passageway for the vertebral artery and accompanying venous plexus through the transverse foramen.

The transverse processes are longer and more prominent in the atlas than in other cervical vertebrae, reflecting their critical role in cervical spine motion, stability, and vascular protection. They also articulate with the superior articular facets of the occipital condyles via the atlanto-occipital joint indirectly through muscular and ligamentous support, contributing to head rotation and lateral bending.

Function

  • Acts as a site for muscular and ligamentous attachments, facilitating neck movements

  • Provides a protective bony conduit for the vertebral artery

  • Maintains cervical spine stability and load distribution

  • Serves as a surgical landmark during cervical spine and vertebral artery interventions

Synonyms

  • C1 transverse process

  • Atlas lateral projection

  • Atlas vertebral process

MRI Appearance

T1-weighted images:

  • Transverse processes appear as low signal intensity (hypointense) cortical bone

  • Marrow within the processes is intermediate to high signal, providing contrast for detecting pathology

  • Surrounding soft tissues and muscles are of intermediate signal intensity

T2-weighted images:

  • Cortical bone remains low signal (hypointense)

  • Bone marrow within the transverse process is intermediate to slightly hyperintense

  • Useful for detecting fractures, edema, or bone marrow pathology

STIR (Short Tau Inversion Recovery):

  • Cortical bone remains low signal

  • Edema, inflammation, or bone marrow lesions appear hyperintense, aiding detection of acute trauma or infection

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal transverse processes show no significant enhancement

  • Pathological processes (tumor, infection, vascular malformation) show enhancement, highlighting abnormal bone or surrounding soft tissue

CT Appearance:

  • Transverse processes appear as hyperdense cortical bone projections extending laterally from the lateral masses

  • Trabecular bone within appears slightly lower in density

  • CT clearly shows fractures, congenital anomalies, osteophytes, or lytic lesions

  • Axial and coronal reconstructions delineate transverse foramen, vertebral artery pathway, and adjacent cervical structures

MRI images

Transverse process of atlas