Neuroanatomy of the equine dorsal cricoarytenoid muscle: surgical implications.
BACKGROUND
Studies are required to define more accurately and completely the neuroanatomy of the equine dorsal cricoarytenoid muscle as a prerequisite for developing a neuroprosthesis for recurrent laryngeal neuropathy.


OBJECTIVE
To describe the anatomy, innervation, fibre types and function of the equine dorsal cricoarytenoid muscle.


METHODS
Thirty-one larynges were collected at necropsy from horses with no history of upper airway disease and 25 subjected to gross dissection. Thereafter, the following preparations were made on a subset of larynges: histochemical staining (n = 5), Sihler's and acetylcholinesterase staining for motor endplates (n = 2). An additional 6 larynges were collected and used for a muscle stimulation study.


RESULTS
Two neuromuscular compartments (NMC), each innervated by a primary nerve branch of the recurrent laryngeal nerve, were identified in all larynges. Stimulation of the lateral NMC produced more lateral displacement of the arytenoid cartilage than the medial NMC (P<0.05). The medial NMC tended to rotate the arytenoid cartilage dorsally. Motor endplates were identified at the junction of the middle and caudal thirds of each NMC. If fibre type grouping was present it was always present in both NMCs.


CONCLUSIONS
The equine dorsal cricoarytenoid muscle has 2 distinct muscle NMCs with discrete innervation and lines of action. The lateral NMC appears to have a larger role in increasing cross-sectional area of the rima glottidis.


CONCLUSIONS
This information should assist in planning surgical reinnervation procedures and development of a neuroprosthesis for recurrent laryngeal neuropathy.
Cheetham
J
J
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Radcliffe
C R
CR
Ducharme
N G
NG
Sanders
I
I
Mu
L
L
Hermanson
J W
JW
D000818:Animals; D001193:Arytenoid Cartilage; D004210:Dissection / Q000662:veterinary; D005260:Female; D006736:Horses / Q000033:anatomy & histology*; D007150:Immunohistochemistry / Q000662:veterinary; D007821:Laryngeal Muscles / Q000033:anatomy & histology* / Q000294:innervation*; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009469:Neuromuscular Junction / Q000033:anatomy & histology*; D012009:Recurrent Laryngeal Nerve; D012143:Respiratory Physiological Phenomena