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Cervical spinal nerve 2 (C2)

The cervical spinal nerve 2 (C2) is the second pair of cervical nerves originating from the cervical segment of the spinal cord, emerging between the atlas (C1) and axis (C2) vertebrae. It is a mixed nerve, transmitting both sensory and motor fibers, and plays a critical role in the innervation of the head and upper neck. C2 is clinically significant due to its involvement in headaches, cervical spine pathologies, and neuralgias.

Synonyms

  • C2 nerve

  • Second cervical spinal nerve

  • C2 spinal nerve

  • Second cervical nerve

Anatomy and Origin

  • Emerges between the first (atlas, C1) and second (axis, C2) cervical vertebrae

  • Part of the eight cervical nerves (C1–C8)

  • Has dorsal (sensory) and ventral (motor) roots

  • Main branches include the greater occipital nerve (dorsal ramus) and lesser occipital nerve (ventral ramus, via cervical plexus)

Function

  • Motor: Supplies muscles such as rectus capitis posterior major/minor and obliquus capitis inferior (via dorsal ramus)

  • Sensory: Innervates the skin of the posterior scalp up to the vertex (via the greater occipital nerve), and partially the upper neck and auricular region

  • Clinical Relevance: Involved in cervicogenic headaches, occipital neuralgia, and certain types of neck pain

MRI Appearance

  • T1-weighted images:

    • C2 nerve root appears as a small, isointense structure relative to spinal cord, surrounded by hyperintense epidural fat

  • T2-weighted images:

    • C2 nerve root shows isointense signal relative to spinal cord, contrasted by hyperintense CSF in the surrounding subarachnoid space

  • STIR sequence:

    • Suppresses surrounding fat signal, enhancing visualization of nerve pathology (e.g., edema, inflammation); C2 nerve may show increased signal if pathology is present

CT Appearance

  • Not directly visible on standard CT, but nerve root canals (neuroforamina) between C1 and C2 can be identified

MRI images

Cervical spinal nerve 2 (C2) MRI axial t2 image