Document Detail


Functional anatomy of the caudal thoracolumbar and lumbosacral spine in the horse.
MedLine Citation:
PMID:  17402454     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
N C Stubbs; P W Hodges; L B Jeffcott; G Cowin; D R Hodgson; C M McGowan
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Equine veterinary journal. Supplement     Volume:  -     ISSN:  -     ISO Abbreviation:  Equine Vet J Suppl     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2007-04-03     Completed Date:  2007-05-02     Revised Date:  2007-05-18    
Medline Journal Info:
Nlm Unique ID:  9614088     Medline TA:  Equine Vet J Suppl     Country:  England    
Other Details:
Languages:  eng     Pagination:  393-9     Citation Subset:  IM    
Affiliation:
The University of Queensland, Australia, University of Sydney, Australia.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biomechanics
Cadaver
Horses* / anatomy & histology,  physiology
Lumbar Vertebrae / innervation,  physiology
Lumbosacral Region / physiology
Magnetic Resonance Imaging / veterinary
Muscle, Skeletal / innervation,  physiology*
Physical Conditioning, Animal / physiology*
Spine / anatomy & histology*,  innervation,  physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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