Equine veterinary journal2026; doi: 10.1002/evj.70350

Anatomical and computed tomographic study of equine cervical spinal nerves and intervertebral foramina.

Stas, EKL
·
Ehrle, A
·
Lischer, CJ

Abstract: Osseous enlargement of the cervical articular process joints due to osteoarthropathy or developmental hypertrophy can narrow the intervertebral foramen (IF), resulting in compression and neuritis of the exiting spinal nerves. Associated clinical signs may include neck pain, forelimb lameness or muscle atrophy. Computed tomography (CT) is the gold standard for IF evaluation; however, to date, visualisation of the equine spinal nerves based on CT imaging is insufficient. Objective: To improve the diagnostic accuracy of foraminal stenosis and cervical spinal nerve (CSN) compression based on CT, this study aims to describe the anatomical size and position of the CSN at the level of the IF. Methods: Cadaveric study. Methods: Anatomical dissection was performed to expose the dorsal and ventral rami of CSN3-CSN8 in 10 cervical specimens (n = 88 IF and CSN). Barium sulfate was applied to the nerves, and CT imaging was performed. The cross-sectional area (CSA) of the IF and CSN, the CSN shape and position within the foramen were quantified. Results: Both IF and CSN CSA significantly increased caudally, with the largest values identified at C7-Th1. The ratio of the spinal nerves CSA to IF CSA was significantly higher caudally, suggesting a greater risk of compression in this region. The CSN position within the IF varied between vertebral levels and was positioned in the mid-caudal third of the IF between C3 and C6 and more cranial in the IFs between C6 and Th1. Conclusions: Ex vivo character of the study and the relatively small sample size. Conclusions: These findings demonstrate significant anatomical variation in the size, shape and position of the CSN inside the IF depending on the vertebral level. Detailed knowledge of these patterns enables increased diagnostic precision and the development of targeted therapeutic interventions in equine CSN compression.

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Publication Date: 2026-10-29 PubMed ID: 42952373DOI: 10.1002/evj.70350Google Scholar: Lookup

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An anatomical and computed tomography (CT) study was conducted to better understand the size, shape, and position of equine cervical spinal nerves (CSN) in relation to the intervertebral foramina (IF), aiming to improve diagnosis of nerve compression caused by foraminal narrowing.

Background and Purpose

Osteoarthropathy or developmental hypertrophy in horses can enlarge the cervical articular process joints, narrowing the intervertebral foramina (IF).
Narrowed IF may compress spinal nerves exiting the cervical spine, causing neck pain, forelimb lameness, or muscle atrophy.
Computed tomography (CT) is the standard imaging technique for evaluating IF stenosis but has limited ability to visualize cervical spinal nerves (CSN).
The study aimed to provide anatomical data on the size, shape, and position of CSNs relative to the IF to improve CT-based diagnoses of nerve compression.

Methods

The study was conducted using 10 cadaveric equine cervical spine specimens, focusing on cervical spinal nerves CSN3 through CSN8.
Anatomical dissection exposed dorsal and ventral rami of the CSNs at 88 IF and CSN sites.
Barium sulfate was applied to the nerves to enhance visibility on CT imaging.
Using CT scans, researchers measured the cross-sectional area (CSA) of both the IF and the CSNs.
The shape and exact positional relationship of the spinal nerves inside the IF were also recorded and quantified.

Results

The cross-sectional areas of both intervertebral foramina and spinal nerves increased moving caudally along the neck (from cervical vertebra 3 to thoracic vertebra 1).
The largest CSA values for both IF and CSN were found at the C7-Th1 level.
The ratio of spinal nerve CSA to IF CSA was significantly higher caudally, indicating that nerves in this region occupy more of the available space and are therefore at greater risk of compression.
The position of the spinal nerves within the foramina varied by vertebral level:

At C3 to C6, nerves tended to lie in the mid-caudal third of the IF.
At C6 to Th1, nerves were positioned more cranially within the IF.

Conclusions and Implications

The study demonstrated significant anatomical variation in the size, shape, and position of equine cervical spinal nerves relative to their foramina along different vertebral levels.
These variations indicate that certain regions of the cervical spine, especially caudal areas such as C7-Th1, are more susceptible to nerve compression due to smaller foraminal space relative to nerve size.
Understanding the precise anatomical relationships enhances the accuracy of CT diagnosis of foraminal stenosis and cervical spinal nerve compression in horses.
This knowledge facilitates more targeted and effective therapeutic interventions, such as surgical decompression or medical management of nerve compression syndromes.
Limitations include the ex vivo nature of the study and a relatively small sample size, which suggest further research may be necessary to generalize findings.

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APA

Stas EKL, Ehrle A, Lischer CJ. (2026). Anatomical and computed tomographic study of equine cervical spinal nerves and intervertebral foramina. Equine Vet J. https://doi.org/10.1002/evj.70350

Publication

Equine veterinary journal

ISSN: 2042-3306

NlmUniqueID: 0173320

Country: United States

Language: English

Researcher Affiliations

Stas, E K L

Equine Clinic, Veterinary Hospital, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.

Ehrle, A

Equine Clinic, Veterinary Hospital, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.

Lischer, C J

Equine Clinic, Veterinary Hospital, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.

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