Autonomic Innvervation Flashcards
Where is the preganglionic sympathetic neuron found?
In the lateral horn of the spinal cord T1-L2
True or false: the sympathetic preganglionic axon exits the spinal cord through the dorsal root.
False. It exits through the ventral root
Where can preganglionic parasympathetic neurons be found?
Midbrain, pons, medulla, or sacral spinal cord
What ocular structures are innervated by the sympathetic nervous system?
Iris dilator, Müller’s muscle, choroidal and conjunctival blood vessels, ciliary muscle, lacrimal gland
What is the pathway of the preganglionic sympathetic neuron?
Lateral horn –> ventral root –> superior cervical ganglion (near vertebrae 2 and 3)
What is the pathway of the postganglionic sympathetic neuron to the iris dilator and ciliary muscles?
Superior cervical ganglion –> sympathetic carotid plexus –> ophthalmic division of CN V –> nasociliary nerve –> long ciliary nerves –> iris dilator and ciliary muscles
What is the result of sympathetic innervation of the iris dilator muscle?
Contraction of the iris dilator, leading to mydriasis
What is the result of sympathetic innervation of the ciliary muscle?
A small inhibition, leading to slight decrease in accommodation
What is the pathway of the postganglionic sympathetic neuron to the choroidal blood vessels?
Superior cervical ganglion –> sympathetic carotid plexus –> ophthalmic division of CN V –> nasociliary nerve –> sympathetic root of ciliary ganglion (no synapse) –> short ciliary nerves –> choroidal blood vessels
What is the result of sympathetic innervation of choroidal blood vessels?
Vasoconstriction
What is the pathway of the postganglionic sympathetic neuron to Müller’s muscle?
Superior cervical ganglion –> sympathetic carotid plexus –> oculomotor nerve –> superior division –> Müller’s muscle
What is the result of sympathetic innervation of Müller’s muscle?
Contraction of smooth muscle in eyelids, widening the palpebral fissure
What is the pathway of the postganglionic sympathetic neuron to the conjunctival blood vessels?
Superior cervical ganglion –> sympathetic carotid plexus –> ophthalmic division of CN V –> nasociliary nerveAt this point the fibers may either enter the sympathetic root of the ciliary ganglion and continue through the short ciliary nerves, or simply continue along the long ciliary nerves.
What is the result of sympathetic innervation of conjunctival blood vessels?
Vasoconstriction
What is the pathway of the postganglionic sympathetic neuron to lacrimal gland blood vessels?
Superior cervical ganglion –> sympathetic carotid plexus –> deep petrosal nerve –> vidian nerve –> pterygopalatine ganglion (no synapse) –> maxillary division of CN V –> zygomatic nerve –> communicating branch –> lacrimal nerve –> lacrimal gland blood vessels
What is the result of sympathetic innervation of lacrimal gland blood vessels?
Vasoconstriction, possibly resulting in decreased tear production
What is another name for the pterygopalatine ganglion?
Sphenopalatine ganglion
True or false: the pterygopalatine ganglion is considered a sympathetic ganglion
False. It is considered a parasympathetic ganglion because parasympathetic fibers synapse here. (Sympathetic fibers pass through but do not synapse here.)
What ocular structures are innervated by the parasympathetic nervous system?
Iris sphincter muscle, ciliary muscle, lacrimal gland
What is the pathway of the preganglionic parasympathetic neuron whose final destination is either the iris sphincter muscle or the ciliary muscle?
Edinger-Westphal nucleus (in midbrain) –> oculomotor nerve –> inferior division –> parasympathetic root of ciliary ganglion (synapse)
What is another name for the Edinger-Westphal nucleus?
Parasympathetic accessory third-nerve nucleus
What is the pathway of the postganglionic parasympathetic neuron to the iris sphincter muscle?
Ciliary ganglion –> short ciliary nerves –> iris sphincter
What is the result of parasympathetic innervation of the iris sphincter muscle?
Contraction, resulting in miosis
What is the pathway of the postganglionic parasympathetic neuron to the ciliary muscle?
Ciliary ganglion –> short ciliary nerves –> ciliary muscle
