Session 6- ANS Hitch-hikers Guide

Question 1

Which NS is the autonomic/ visceral NS a part of?

Answer 1

Peripheral (spinal and cranial nerves) - central control from hypothalamus

Maintains and fine tunes internal environment - accelerator and brake

Question 2

How does the two neurone arrangement differ between the parasympathetic and sympathetic NS?

Answer 2

Parasympathetic:
~long pre-ganglionic neurone. craniosacral Brainstem (PS nuclei) -> hitch-hike on one of 4 cranial nerves (3,7,9,10) OR sacral outflow from S2-S4 -> Ach
~ PS ganglia -> ~ post short.
hitch-hike on branches of CN 5 (bar CN10) -> ACh -> target tissues

Sympathetic:
~short pre. Thoracolumbar Spinal cord T1-L2 lateral horn grey matter -> Ach -> ~ganglia top of sympathetic chain (superficial cervical or middle cervical) -> NA/A -> ~long post. -> hitch-hike on BVs (distally join branches CN5/ CN3 reach muscles eye) -> effector tissues

Question 3

What do parasympathetic pre-ganglionic And post neurones hitch-hike along?

Answer 3

pre: Cranial nerves 3,7,9,10

Post: CN 5 bar CN10

Question 4

What do sympathetic post-ganglionic neurones hitch-hike along?

Answer 4

Pre- nothing

Post- blood vessels
Common carotid A ->
Internal carotid artery -> cavernous sinus -> ophthalmic A -> eye

CCA-> external CA -> to external face

Question 5

What are the effector tissues of sympathetics?

Answer 5

Smooth muscle of BVS,

Eye lid (tarsal muscle),

Iris (dilator papillae),

Sweat glands,

Arrector pili muscles (hair follicles),

Decreases secretions salivary/ lacrimal glands (higher protein more viscous)

Question 6

What are the effector tissues of parasympathetics?

Answer 6

Smooth muscles iris (sphincter pupillae),

muscle ciliary body iris (controls thickness lens),

Lacrimal glands,

Salivary glands,

Mucosal glands,

SM respiratory and GI tract

Question 7

What is Horner’s syndrome? what are some causes?

Answer 7

Symptoms: anhydrous, lack sweating, partial ptosis (levator papillae SM small compartment, if CN3 lesion much greater ptosis), miosis

Causes:
CCA and branches/ lung apex pathology cause autonomic dysfunction eye and face e.g. aneurysms, pancoast tumour

Question 8

The route of parasympathetic pre-ganglionic neurone Edinger Westphal

Answer 8

Brainstem -> hitch- hikes on CN3 (oculomotor) -> ciliary ganglia (back of orbit) -> hitch-hikes along CN5a (trigeminal) -> smooth muscles sphincter pupillae and ciliary muscle controls lens

Question 9

The route of parasympathetic pre-ganglionic neurone superior salivary

Answer 9

Brainstem -> CN 7 (facial) -> submandibular/ pterygopalatine ganglia -> CN5 (trigeminal) -> lacrimal gland

Question 10

The route of parasympathetic pre-ganglionic neurone inferior salivary

Answer 10

Brainstem -> CN9 (glossopharyngeal) -> otic ganglia -> CN5 (trigeminal c) -> salivary gland (parotid)

Question 11

The route of parasympathetic pre-ganglionic neurone dorsal motor

Answer 11

Brainstem -> CN 10 (vagus) -> ganglion at/ in target tissues -> mucosal glands pharynx/ larynx, SM oesophagus/ trachea, SM and mucosal glands resp/ GI tract, heart

Different bc post-ganglionic doesn’t hitch-hike along trigeminal N
Long route

Question 12

Describe the pupillary light reflex

Answer 12

Light -> afferent limb optic nerve -> (some branches leave to enter midbrain & synapse in pre-tectal nucleus) optic chiasm -> optic tract -> Brain stem -> both sides connect Edinger Westphal nuclei -> pre with oculomotor N efferent limb -> ciliary ganglion -> constrict pupils sphincter pupillae

If shine light in one eye should constrict simultaneously

Question 13

What are the two branches of the facial nerve that parasympathetics reach target tissues by?

Answer 13

Internal acoustic meatus -> Both arise in petrous bone

• greater petrosal Nerve -> pterygopalatine ganglion -> lacrimal gland/ mucosal glands nasal/ palate

chorda tympani N -> submandibular ganglion -> salivary glands (bar parotid)

-> trigeminal (lingual) N

Question 14

What branches does the glossopharyngeal N split into after it exits the jugular foramen? Describe the rest of the route?

Answer 14

Tympanic N -> sensory middle ear

Parasympathetics (run with tympanic -> exit middle ear as lesser petrosal N -> foramen ovale -> optic ganglion (infratemproal fossa) -> Vc N -> parotid G

Question 15

What the difference between a nucleus and a ganglion?

Answer 15

Both a collection of nerve cell bodies

Nucleus: within the CNS

Ganglion: outwith the CNS and in PNs either relation to autonomic nerves (sympathetic chain ganglion) or sensory nerves (dorsal root ganglion)