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Neurology Networks tries to offer broad exposure to various topics that may be presented on the veterinary neurology board exam.

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Pathophysiology 3

Pathophysiology 3

Q.  Describe the pathway for the sympathetic innervations to the pupil.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A. 

*First order neurons (UMN) originate in the hypothalamus and travel through the tectotegmental system of the brainstem, along the lateral funiculus of the spinal cord to the lateral grey column at the level of the T1-3 spinal cord segments before synapsing in the paravertebral sympathetic ganglia. 

*The second order neurons (preganglionic) will travel through the thorax, mediastinum, and thoracic inlet to travel up the neck with the vagosympathetic trunk.  The neurons will pass through the cervicothoracic and middle cervical ganglia to synapse in the cranial cervical ganglion that is near (usually just caudal to) the middle ear cavity. 

*The third order neurons (postganglionic) will then pass through the middle ear cavity, along the skull base near the carotid sinus, then through the orbital fissure to synapse on the ciliary ganglion.  This path is ill-defined.

 

http://neurovet.me/special-topics/horners-syndrome/

Veterinary Neuroanatomy and Clinical Neurology, 3rd edition.  De Lahunta, Glass.  Saunders Elsevier 2009: pp 173-174