Ultrasound Scan of the Occipital and Upper Cervical Region

The sonoanatomical knowledge of the upper cervical and occipital region is critical for the identification of structures involved in the pathophysiology of cervicogenic headache and neck pain. We propose a systematic caudo-cranial ultrasound scan using a paramedial transverse view. The first relevant structure to identify is the Obliquus Capitis Inferior Muscle (OCIM) that in turn will allow us to locate the Great Occipital Nerve (GON), the C1-C2 joint, the C2 dorsal root ganglion, medial to the joint, and the Vertebral Artery, lateral to the joint. Sonogram 1 demonstrates the great occipital nerve (GON) between the seminspinalis capitus muscle (SMCEM) and obliquus Capitis Inferior Muscle (OCIM) and the C1-C2 joint. Aligning the transducer obliquely along the long axis of the OCIM, may allow for better visualization of the muscle. With a cranial displacement of the probe, one can identify the posterior arch of C1 and the vertebral artery as it transverses from lateral to medial crossing the medial posterior aspect of the atlanto-occipital joint (sonograms 2 and 3). Finally, with more cranial scan, one can identify the occipital bone and the occipital artery near the distal branches of the greater occipital nerve and third occipital nerve more medially (Sonogram 4). With continued cranial scanning the GON will be more superficial as it pierces the trapezius aponeurosis.