ANS Flashcards
What is the ANS and what does it supply?
Part of the PNS that controls SM and glands. Controls body functions not under conscious control
What is the neurone arrangement of the ANS?
Pre ganglionic -> ganglionic -> post ganglionic
Where do symp nerves arise from?
Thoracolumbar SC (T1-L2)
Where do parasymp nerves arise from?
The brainstem (cranial) and sacral (S2-4)
What are the actions of the symp NS?
“Fight or flight”: vasoconstriction, eyelid retraction (tarsal muscle), iris dilator (dilator pupillae), stim sweat glands and arrector pili, decrease lacrimal and salivary secretions
What are the functions of the parasymp NS?
“Rest and digest”: sphincter pupillae (constricts) and ciliary body, stimulates lacrimal, salivary and mucosal glands
What do symp fibres mostly hitchhike on?
Blood vessels and branches of CNS
What is the anatomical course of the symp nerves?
SC -> symp chain -> cervical ganglion -> hitchhike on carotid plexus and breaches of CNS -> SM/glands
What two anatomical relations are important to symp nerves? Why?
Carotid arteries and lung apex. E.g pancoast tumour
Pathology here can -> AN dysfunction in eye and face
What are the presenting features of Horner’s Syndrome? Why does it occur? What are 2 causes?
Miosis, partial ptosis, +/- anhydrosis.
Occurs due to disruption to symp nerve supply to H and N.
Apical lung tumour, carotid artery dissection (neck pain) disrupt it
What are the 2 ganglia of the symp NS?
Sup cervical and middle cervical
Which CNs carry parasymp fibres?
Occulomotor, facial, glossopharyngeal, vagus (3,7,9,10)
What are the 4 parasymp ganglion called? Wha do they all hitchhike on?
Ciliary, perygopalatine, submandibular, otic.
Hitchhike onto one of the 4 CNs then ganglia then ALL hitchhike on a branch of the trigeminal
What is the course of the parasymp oculomotor nerve?
Edinger Westphal nucleus, fibres hitchhike onto OM nerve to ciliary ganglion then on opthalmic (trigeminal) to EYE: ciliary body, sphincter pupillae
Parasymp fibres hitchhike on which two branches of the facial nerve?
Chords tympani an greater petrosal
Which ganglion do the parasymp fibres hitchhiking on chorda tympani go to? What do they innervate?
Submandibular -> hitchhike on trigeminal to submandibular and sublingual salivary glands
Which ganglion do the parasymp fibres hitchhiking on greater petrosal go to? What do they innervate?
Pterygopalatine ganglion -> hithhike on trigeminal to lacrimal, nasal and oral mucosal glands
What is the difference between pathology in the facial nerve before and after the geniculate ganglion?
Pathology at or before may involve all parasymp functions (eye fine, dry mouth and loss of muscles of mastication).
After will not involve greater petrosal (lacrimal spared)
Which ganglion do the parasymp fibres hitchhiking on glossopharyngeal nerve go to? What do they innervate?
Tympanic nerve and lesser petrosal carry parasymp fibres. Go to otic ganglion then to parotid gland via mandibular (trigeminal)
Where do the parasymp fibres hitchhiking on vagus nerve go to? What do they innervate?
Hitchhike on trigeminal then to thorax, abdomen, glands in larygopharynx, larynx, oesophagus and trachea
