5. Discuss, with the aid of diagrams, the autonomic control of 
    lacrimal secretion. 
Paraympathetic supply originates as preganglionic fibres from the superior salivatory nucleus. They travel in the nervus intermedius and leave the middle ear as the greater petrosal nerve to enter the middle cranial fossa. The fibres enter the pterygoid canal and travel to pterygopalatine fossa. Synapses occur in the pterygopalatine ganglion. The post-ganglionic fibres travel along the zygomaticotemporal and lacrimal nerves to innervate the lacrimal gland.

The first order fibres of sympathetic nerve originate in hypothalamus and travel down the spinal cord to synapse at the intermiodlateral grey horn. The second order fibres exist the spinal cord to enter the sympathetic chain and synapse at the superior cervical ganglion. The third order fibres ascend in the internal carotid plexus and enter the deep petrosal nerve. The fibres then join the greater petrosal nerve and innervate the lacrimal gland viat the zygomaticotemporal and lacrimal nerves.

The parasympathetic nerve mediates the reflex lacrimation and the sympathetic nerve the basal secretion.

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