ANS

Question 1

What part of the nervous system is the ANS part of?

Answer 1

Peripheral nervous system that controls smooth muscle and glands

Question 2

Describe the neuronal arrangement of the ANS

Answer 2

Pre-ganglionic N – ganglion – post ganglionic N

Question 3

What is a ganglion?

Answer 3

Collection of cell bodies

Question 4

What is the equivalent of a ganglion in the CNS?

Answer 4

nuclei

Question 5

What is the location of the autonomic outflow?

Answer 5

Sympathetic = thoracolumbar, T1-L2, cell bodies in lateral horn of grey matter of spinal cord

Parasympathetic = craniosacral, brainstem, S2-S4, cell bodies (nuclei) in brainstem or grey matter of sacral spinal cord

Question 6

How do sympathetics reach structures in the head and neck?

Answer 6

Axon leaves spinal cord (mainly T1/2) = meets sympathetic chain (chain of ganglion) = doesn’t synapse but ascends up sympathetic trunk = now in the superior CERVICAL ganglion = pre-ganglionic N meets cell body of post ganglionic N = hitch hikes on common carotid – internal/external = through base of the skull via carotid canal =

internal carotid A to the ophthalmic A to the eye = can also travel along the oculomotor and trigeminal Ns (superior tarsal muscle, dilator pupillae)

external carotid A to the sweat glands and blood vessels of face/neck

Question 7

Top 3 ganglion in the cervical chain are called?

Answer 7

The cervical ganglion = due to location in the neck

Question 8

What is the carotid plexus?

Answer 8

Sympathetic Ns having arisen from the ganglion making their way up the neck by associating with the carotid artery

Question 9

How can pathology involving the apex of the lung cause autonomic dysfunction in the eye and face?

Answer 9

Lung cancer – pancoast tumour = interrupt sympathetic supply as the axons leave the spinal cord - to the face/eye

Clinical appearance = partial ptosis, constricted pup (miosis), anhidrosis (lack of sweating) = Horners syndrome

Question 10

What is horners syndrome?

Answer 10

Interruption of the sympathetic nerves to 1/2 face/eye

Clinical appearance = partial ptosis, constricted pup (miosis), anhidrosis (lack of sweating) = Horners syndrome

Causes = lung apex cancer, pathology of the carotid artery

Question 11

Which cranial nerves carry parasympathtic fibres from the brainstem?

Answer 11

Oculomotor

Facial

Glossopharngeal

Vagus

Question 12

How do parasympathetic fibres reach the head and neck?

Answer 12

Arise from brainstem

Hitch-hike on 1 of 4 CNs

Ganglion

Synapse with post-ganglionic parasympathetic axon

Hitch-hike on trigeminal N

To target tissue = constricting smooth muscle in iris, ciliary muscle, lacrimal gland, mucosal gland, salivary glands

Question 13

Name the parasympathetic ganglion

Answer 13

Ciliary = oculomotor N

Submandibular = facial N

Pterygopalatine = facial N

Otic = glossopharyngeal

Question 14

What is the name of the important parasympathetic nuclei?

Answer 14

Edinger westphal

Question 15

Outline the pupillary-light reflex

Answer 15

1) Light in L pupil
2) Sensory afferent OPTIC N from L retina
3) Some branches leave the optic nerve to enter midbrain
4) Connect with edinger-westphal nuclei L and R
5) Parasympathic fires from EDW leave brainstem
6) Hitch-hike on OCCULOMOTOR N L and R
7) Pass via ciliary ganglion
8) Reach sphincter pupillae
9) Direct light reflex L pupil, consensual light reflex R pupil

Question 16

Outline how the parasympathetic Ns travel the oculomotor N

Answer 16

Brainstem – edinger westpahl nucleus

Pre-ganglionic hitch-hikes on oculomotor N

Ciliary ganglion

Post-ganglionic hitch-hikes on trigeminal

Ciliary body (constrictor of pupil)

Question 17

Outline how the parasympathetic fibres travel the facial N

Answer 17

Parasympathetic pre-ganglionic emerges from brainstem hitch hiking on facial N

Into petrous bone

At point of geniculate ganglion

1) greater petrosal N leaves = to pterygopalatine fossa containing pterygopalatine ganglion – post-ganglionic parasympathetics hitch-hikes via trigeminal N to lacrimal/nasal/palatine glands
2) chorda tympani N leaves = crosses middle ear cavity, exiting base of skull – submandibular ganglion – post-ganglionic parasympathetics hitch hike via trigeminal N to tongue/sublingual/submandibular glands

Question 18

Outline how the parasympathetic fibres travel the glossopharngeal N

Answer 18

Parasympathetic pre-ganglionic emerges from brainstem hitch-hiking on glossopharngeal N

Through jugular foramen

Gives off tympanic N (sensory to middle ear)

Travel inside the petrous bone

Exits as the lesser petrosal N

Synapse with otic ganglion

post-ganglionic parasympathetics hitch hike via trigeminal N to parotid gland

Question 19

Outline how the parasympathetic fibres travel the vagus N

Answer 19

Parasympathetic pre-ganglionic emerges from brainstem hitch-hiking on Vagus N

Meets ganglion in target tissues

Post ganglion fibres inside

1) glands
2) heart
3) smooth muscle in resp/GI

Question 20

Which branches of the facial N arise within the petrous part of the temporal bone?

Answer 20

greater petrosal N

chorda tympani branch

nerve to stapedius

Question 21

If there is a small tumour of the vestibulocochlear N in the area of the internal acoustic meatus, which other cranial N may be affected?

Answer 21

CN 7 - facial N