136 VETERINARY STATE BOARD 



pupil, secretory fibres to the sweat, salivary and sebaceous glands, 

 motor fibres to the muscles of the hair, and influences the process 

 of nutrition in general. 



Mention the three classes of S3mipathetic nerve ganglia, giving the 

 function of each. 



1. Vertebral ganglia, afford connection with the cerebrospinal 

 system. 



2. Collateral ganglia, including the cardiac, solar and mesenteric 

 plexuses which send branches to the various organs, supplying them 

 with accelerator, vasomotor and secretory fibres, and carrying from 

 them afferent impulses. 



3. Terminal ganglia, fibres originating in the collateral ganglia 

 and terminating in the tissues, control certain reflexes. 



Senses 



Name the appendages of the eye and state the function of each. 



Eyelashes: protective function; they give warnings of danger. 



Eyelids: two in number, protective covering. 



Membrana nictitans: third eyelid, removes foreign bodies. 



Meibomian glands: secrete an oily liquid to lubricate the edges 

 of the lids and prevent the overflow of tears. 



Con jimctiva : a mucous membrane which provides a smooth glid- 

 ing surface between the lids and the cornea. 



Caruncle: small, red elevation at the inner canthus, which 

 directs the tears toward the puncta. 



Lachrjonal apparatus: secrete and carry away the tears which 

 lubricate the cornea and inner side of the lids. 



Ocular sheath: binds the structures of the orbit together. 



What is the function of the iris? Describe the innervation of the iris. 



The iris regulates the amount of light passing into the eye. Its 

 circular fibres are supplied by the third pair of cranial nerves and 

 its dilator fibres are innervated by the sympathetic. 



What structures in the horse's eye serves the purpose of the human 



eyebrow? Describe clearly the position, attachments and 



movements of this structure. 



The membrana nictitans. It is situated in the inner angle of 



the eye, and is continued posteriorly by a strong, adipose cushion 



which insinuates itself between all the muscles of the eyeball. When 



the recti muscles retract the eye in the orbit, this fatty cushion is 



forced outwardly and the membrana nictitans is forced forward 



over the eye. 



