Functional anatomy of the caudal thoracolumbar and lumbosacral spine in the horse

Stubbs, N. C., Hodges, P. W., Jeffcott, L. B., Cowin, G. J., Hodgson, D. R. and McGowan, C. M. (2006). Functional anatomy of the caudal thoracolumbar and lumbosacral spine in the horse. In: B. Essén-Gustavsson, E. Barrey, P. M. Lekeux and D. J. Marlin, Equine Veterinary Journal Supplement. Proceedings of: 7th International Conference on Equine Exercise Physiology. ICEEP 7: 7th International Conference on Equine Exercise Physiology: 7e conférence internationale de physiologie de l'exercicechez le cheval, Fontainebleau, France, (393-399). 26-31 August 2006.


Author Stubbs, N. C.
Hodges, P. W.
Jeffcott, L. B.
Cowin, G. J.
Hodgson, D. R.
McGowan, C. M.
Title of paper Functional anatomy of the caudal thoracolumbar and lumbosacral spine in the horse
Conference name ICEEP 7: 7th International Conference on Equine Exercise Physiology: 7e conférence internationale de physiologie de l'exercicechez le cheval
Conference location Fontainebleau, France
Conference dates 26-31 August 2006
Proceedings title Equine Veterinary Journal Supplement. Proceedings of: 7th International Conference on Equine Exercise Physiology   Check publisher's open access policy
Journal name Equine veterinary journal. Supplement   Check publisher's open access policy
Place of Publication Newmarket, U.K.
Publisher Equine Veterinary Journal
Publication Year 2006
Sub-type Fully published paper
ISBN 027976589 (Invalid)
ISSN 0425-1644
Editor B. Essén-Gustavsson
E. Barrey
P. M. Lekeux
D. J. Marlin
Volume 36
Issue 36
Start page 393
End page 399
Total pages 7
Collection year 2006
Language eng
Formatted Abstract/Summary
Reasons For Performing Study
Research in spinal biomechanics and functional anatomy has advanced back pain research in man. Yet, despite the performance limiting nature of back pain in horses, there are few data for the equine spine.

Objectives
To describe aspects of functional anatomy of the equine thoracolumbar and lumbosacral (LS) spine and potential effects on performance.

Methods
The first study investigated variations in LS vertebral formula by post mortem examination of 120 horses. Midline vertebral transection was carried out on 65 Thoroughbred (TB), 24 Standardbred (SB) and 31 other breeds. The second study investigated morphology and biomechanics of the deep stabilising epaxial muscles of 13 horses using MRI (n = 3), anatomical dissection (n = 11) and biomechanical analysis (n = 6). The spinous process angular orientation relative to the vertebral body, was analysed at vertebrae T13, T18, L3, L5, L6 and S1.

Results
LS variations were found in 33.3% of the total group, 40.0% TB and 45.2% others, but 0% SB. Sacralisation of lumbar vertebra (L) 6 with LS motion between L5 and L6 occurred in 32.3% TB and 29.0% others. Five segmental multifidus fascicles were identified originating from spinous processes and vertebral laminae running craniocaudally onto the mammillary processes and lateral border of the sacrum, crossing between 1-5 intervertebral discs. Sacrocaudalis dorsalis (SCD) lateralis muscle was an extension of multifidus from L4, L5 and L6 depending on the vertebral formula whereas SCD medialis mm originated from S3. Both inserted on caudal vertebrae. Based on the location and direction of fibres, the principal action of the deep epaxial muscles was dorsoventral sagittal rotation. This action was dependent on vertebral spinous process/body orientation. We hypothesise that equine multifidus and SCD lateralis muscles act as caudal sagittal rotators of their vertebra of origin, as is the case in man, allowing dynamic stabilisation during dorsoventral motion.

Conclusion
Equine multifidus anatomy and function are comparable to that of man. The high prevalence of anatomical variations in the LS spine may affect maximal dorsoventral motion, the stability of the LS joint and, therefore, have consequences for athletic performance. Further studies of these structures are warranted in appropriately selected poorly performing horses.
Subjects E1
300500 Veterinary Sciences
630107 Minor livestock (e.g. horses, goats, deer)
0707 Veterinary Sciences
Keyword Horse
Back pain
Multifidus
Vertebral formula
Biomechanics
Q-Index Code E1
Additional Notes Presented during "Skeletal biomechanics and locomotion: oral presentations"

 
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Created: Thu, 23 Aug 2007, 21:51:05 EST