34th Annual Scientific Meeting proceedings

Objectives:

Ultrasound-guided injection techniques and surgical foraminotomy to treat radiculopathy and intervertebral foraminal stenosis have been published. However, the exact anatomy of the spinal nerves exiting the intervertebral foramen is poorly described. The aims were to describe the gross anatomy and CT-visibility of the spinal nerves and intervertebral foramina, as a basis for further diagnostics and treatments.

Methods:

A cadaveric study was conducted on ten equine necks. A Qualibra CT scan was performed before and after dissection of the soft tissues around the intervertebral foramina from C3 to C7. On both sides of the neck, the dorsal and ventral rami of the spinal nerves were traced back to the intervertebral foramen. The course of the nerves inside the intervertebral foramen was documented and compared with CT images.

Results:

The spinal nerve exits through the caudal half of the intervertebral foramen, formed by the cranial articular process, the cranial notch of the vertebral arch and the cranial part of the vertebral body of the caudal vertebra. The dorsal branch runs in a caudodorsal direction over the cranial articular process. The ventral branches run cranial to the processus transversus and pass ventral to its distal end. They are embedded in the deep cervical musculature and tendinous insertions. The spinal nerves could only be localised on CT-images after dissection.

Conclusions:

The emerging spinal nerves fill the caudal half of the intervertebral foramen. With current available CT modalities, the spinal nerves were not visible on native CT images. This knowledge could aid in the further development of imaging and surgical techniques.