Proximal cervical spinal nerve: MR appearance

An interradicular cleft and a segment of nerve containing fascicles have recently been described in the cervical spinal nerve. This study was performed to determine whether the fascicles and the interradicular cleft have a distinctive appearance on magnetic resonance (MR) images. The proximal spinal nerves and nerve roots of C-4 and C-8 were removed from cadavers, imaged with MR, sectioned, and stained. Cervical neural foramina were imaged with MR and then sectioned. The MR images demonstrated a division of the root sheaths into ventral and dorsal portions, separated by fat within the interradicular cleft and located proximal to the dorsal root ganglion. Distal to the dorsal root ganglion, the proximal portion of the cervical spinal nerve containing multiple fascicles gave the proximal portion of the spinal nerve an inhomogeneous appearance on the MR images. This study suggests an anatomic explanation for the variable appearance of the cervical spinal nerves with MR imaging.