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Frontiers in veterinary science2021; 8; 652563; doi: 10.3389/fvets.2021.652563

Correlated Imaging of the Equine Hyoid Apparatus Using CT, Micro-CT, and Histology.

Abstract: Detailed radiological evaluation of the normal hyoid apparatus by computed tomography (CT) has not yet been conducted. Thus, it is unclear what type of junction connects the different parts of the equine hyoid apparatus. To describe the normal CT anatomy of the equine hyoid apparatus, and to determine the junction type that connects the different parts of the hyoid apparatus. Combination of retrospective study and prospective cadaver study. The medical records of horses that underwent head CT scans from 2009 to 2018 were retrieved. Inclusion criteria for the CT scans were visibility of at least two of the four junctions of the hyoid apparatus. CT images were analyzed in three different planes. Additionally, 10 cadaver heads were processed using CT, micro-CT of selected joints, and histology of all joints. CT scans of 200 horses fulfilled the inclusion criteria. The tympanohyoid cartilage consisted of hyaline cartilage. Areas of mineralization within the cartilage were visible on CT scans as early as 2 years of age. The epihyoid was not fused with the stylohyoid in one-third of the horses. All horses younger than 2.5 years showed three ossification centers of the basihyoid, and all horses younger than 1.5 years had a non-fullydeveloped lingual process. In total, 10 of 11 horses between 1.5 and 3 years had separate ossification centers of the lingual process. We found a synchondrosis between the styloid process and the stylohyoid bone. The basihyoid and thyrohyoid, as well as the stylohyoid and epiyhoid were connected by a synostosis in two-thirds of the horses. The remaining parts were connected to one another by synovial joints. The junctions studied by histologic examination were from older horses, therefore growing patterns of different bones could not be totally clarified. The temporohyoid joint is a synchondrosis. The epihyoid is an ossification center of the stylohyoid and fuses with the stylohyoid in two-thirds of horses. The lingual process has a separate ossification center.
Copyright © 2021 Hartl, Egerbacher and Kneissl.
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Publication Date: 2021-07-05 PubMed ID: 34291098PubMed Central: PMC8287096DOI: 10.3389/fvets.2021.652563Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study investigates the anatomy of the equine hyoid apparatus, which has not previously been evaluated in detail with computed tomography (CT). The researchers used CT scans, micro-CT, and histology to examine the structures and connections within the hyoid apparatus of horses.

Study Design and Data Collection

  • The research is a combination of retrospective and prospective cadaver studies. The CT images of 200 horses were analyzed. These horses underwent head CT scans as part of their healthcare between 2009 and 2018.
  • The horses included in the study had to have at least two visible junctions of the hyoid apparatus on their CT scans.
  • These images were analyzed in three different planes to gain a thorough understanding of the structure of the hyoid apparatus.
  • In addition to the retrospective study, cadaver heads were also examined using CT scans. Micro-CT was used for specific joints, while histology was used on all joints for deeper insights.

Research Findings

  • The study revealed the tympanohyoid cartilage consists of hyaline cartilage. Evidence of mineralization within the cartilage was visible on CT scans as early as two years of age.
  • The epihyoid was found not to be fused with the stylohyoid in a third of the horses studied.
  • Horses under 2.5 years old displayed three ossification centers in the basihyoid, and all horses under 1.5 years old had an underdeveloped lingual process.
  • Between ages 1.5 and 3, 10 out of 11 horses had separate ossification centers in the lingual process.
  • The styloid process and the stylohyoid bone were determined to be connected by a synchondrosis. The connections between the basihyoid and thyrohyoid, and the stylohyoid and epiihoid were found to be synostoses in two-thirds of the horses. The remaining parts were connected via synovial joints.

Limitations and Conclusions

  • The histologic examination studied older horses, which meant that the researchers were unable to completely clarify growth patterns of different bones within the hyoid apparatus.
  • The researchers concluded that the temporohyoid joint is a synchondrosis. The epihyoid is an ossification center of the stylohyoid and fuses with it in two-thirds of horses. The lingual process has a separate ossification center.

Cite This Article

APA
Hartl B, Egerbacher M, Kneissl SM. (2021). Correlated Imaging of the Equine Hyoid Apparatus Using CT, Micro-CT, and Histology. Front Vet Sci, 8, 652563. https://doi.org/10.3389/fvets.2021.652563

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 8
Pages: 652563
PII: 652563

Researcher Affiliations

Hartl, Bettina
  • Department of Pathobiology, Institute of Topographic Anatomy, University of Veterinary Medicine Vienna, Vienna, Austria.
Egerbacher, Monika
  • Administrative Unit Veterinary Medicine, UMIT Tirol - Private University for The Health Sciences, Medical Informatics and Technology GmbH, Hall in Tirol, Austria.
Kneissl, Sibylle Maria
  • Department for Small Animals and Horses, Clinical Unit of Diagnostic Imaging, University of Veterinary Medicine Vienna, Vienna, Austria.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Citations

This article has been cited 3 times.
  1. Piagkou M, Triantafyllou G. The Stylohyoid Complex: An Update on Its Embryology, Comparative Anatomy and Human Variations. Biology (Basel) 2025 Oct 27;14(11).
    doi: 10.3390/biology14111500pubmed: 41300292google scholar: lookup
  2. Hartl B, Strohmayer C, Vali Y, Lyrakis M, Kneissl SM. Computed tomographic signs of hyoid apparatus disease in 165 horses. Front Vet Sci 2025;12:1631185.
    doi: 10.3389/fvets.2025.1631185pubmed: 41049149google scholar: lookup
  3. Lloyd-Edwards RA, Mulders E, Sloet van Oldruitenborgh-Oosterbaan MM, Veraa S. Computed Tomography of the Hyoid Apparatus in Equine Headshaking Syndrome. Vet Sci 2025 May 23;12(6).
    doi: 10.3390/vetsci12060511pubmed: 40559747google scholar: lookup
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