Document Detail

Anatomy and Anaesthesia of the Equine External Ear Canal.
MedLine Citation:
PMID:  22432970     Owner:  NLM     Status:  Publisher    
Anaesthesia of the external ear canal (external acoustic meatus) is usually performed by blocking both the great and internal auricular nerves by regional infiltration. However, exact landmarks for blocking the internal auricular nerve to accomplish effective anaesthesia have not been described yet. In this study, detailed anatomical dissection of the equine external ear canal and its nerve supply was carried out on fifteen cadaver heads. Tissue samples of the dissected nerves were taken from two cadaver heads processed and were evaluated microscopically. Prior to the dissection, the region of interest was evaluated ultrasonographically, and injection of a local anaesthetic was simulated with an injection of methylene blue on ten cadaver heads. The tympanic membranes of three cadaver heads were obtained by microdissection and processed for microscopic evaluation. The entrance point of the internal auricular nerve, which is a branch of the facial nerve, into the ear canal is formed by the styloid process of the auricular cartilage. Using ultrasound, the styloid process presented as a thin hyperechoic line 2.17-2.97 cm deep, based on the skin surface. Landmarks for performing a complete and reliable anaesthesia of the external ear canal were established, and the simulated anaesthesia with methylene blue injection was evaluated as successful in all ten cases. Additionally, the histological composition of the equine tympanic membrane is described and illustrated.
S Sommerauer; C K W Muelling; J Seeger; G F Schusser
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-3-21
Journal Detail:
Title:  Anatomia, histologia, embryologia     Volume:  -     ISSN:  1439-0264     ISO Abbreviation:  -     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-3-21     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7704218     Medline TA:  Anat Histol Embryol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2012 Blackwell Verlag GmbH.
Department of Large Animal Medicine, Faculty of Veterinary Medicine, University of Leipzig, Anden Tierkliniken 11, 04103 Leipzig, Germany.
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