Anatomy and Ultrasound-Guided Injection of the Medial Branch of the Dorsal Ramus of the Cervical Spinal Nerves in the Horse: A Cadaveric Study

Abstract

Objectives The aim of this study was to describe the anatomy of the nerves supplying the cervical articular process joint and to identify relevant anatomical landmarks that could aid in the ultrasound-guided location and injection of these nerves for diagnostic and therapeutic purposes. Study Design Twelve cadaveric equine necks were used. Five necks were dissected to study the anatomy of the medial branch of the dorsal ramus of the cervical spinal nerves 3 to 7. Relevant anatomical findings detected during dissections were combined with ultrasonographic images obtained in one other neck. Six additional necks were used to assess the accuracy of ultrasound-guided injections of the medial branch with blue dye. Results Each examined cervical articular process joint, except for C2 to C3, presented a dual nerve supply. The articular process joints were found to be in close anatomical relationship with the medial branch of the dorsal ramus of the cervical spinal nerve exiting from the intervertebral foramen at the same level, and with the medial branch of the dorsal ramus of the cervical spinal nerve exiting from the intervertebral foramen one level cranial to the articular process joint of interest. A total of 55 nerves were injected under ultrasonographic guidance, 51 of which were successfully stained. Conclusion The current study provided new detailed information regarding the innervation of the cervical articular process joint. The medial branches of the dorsal rami of the cervical spinal nerves were injected with an accuracy that would be of clinical value. Our study offers the foundations to develop new diagnostic and therapeutic techniques for pain management in cervical articular process joint arthropathy in horses.

Refining the rat sciatic nerve block: a novel ultrasound-guided technique

“…The proceduralist in this study has significant experience in ultrasound-guided regional anesthesia techniques in humans; however, this was not a technically challenging procedure. Ultrasound guided nerve blocks are increasingly being used in veterinary medicine, 9 and this represents a reasonable extension of prior large animal studies. Adaptation for this procedure for use in mice may be difficult or impossible due to the decrease in size.…”

Implications of the neuroanatomy of the equine thoracolumbar vertebral column with regional anaesthesia and complications following desmotomy of the interspinous ligament

“…17 The articular process joints of the thoracolumbar vertebrae of horses, dogs, and humans have dual segmental innervation supplied by the medial branch of the dorsal ramus; 20,22,32,40,41 this has been demonstrated in the cervical vertebrae of horses except at cervical vertebrae C2-C3. 42 In dogs, this dual innervation is provided by small terminal branches from the medial branch that innervate the caudal aspect of the articular process joint at that level, and small terminal branches that innervate the cranial aspect of the articular process joint of the next caudal vertebrae. In horses, however, this dual innervation is supplied by two separate branches of the medial branch.…”

“…In horses, however, this dual innervation is supplied by two separate branches of the medial branch. 22 As the medial branch emerges from the intertransverse space, it divides into four distinct branches in the cervical region, 42 and two distinct branches in the thoracolumbar region, one of which courses caudodorsally around the process of the articular process joint at the same level to innervate the caudal aspect of the articular process joint, while the second branch continues caudally to innervate the cranial aspect of the articular process joint of the next caudal vertebra. 22 The interspinous ligament of horses contain dense sensory innervation, 43 which likely arises from the medial branch of the dorsal ramus, as it does in man.…”

Arthroscopic removal of osteochondral fragments of the cervical articular process joints in three horses

“…6,25 Ultrasonography was considered necessary to improve orientation and reduce the risk of iatrogenic damage to the periarticular neurovascular structures. [24][25][26] A point 1 cm cranial and 1 cm ventral to the C 5 -C 6 APJ was determined radiographically. A 20G Â 3½ 00 spinal needle was inserted under ultrasonographic guidance and directed in an approximately 60 cranioventral-caudodorsal angle to reach the cranioventral joint recess at the visible joint space.…”