9. Autonomic Nervous System

Question 1

What is the autonomic nervous system?

Answer 1

Part of the peripheral nervous system that controls smooth muscle and glands (not under conscious control).

Question 2

How are neurones in the autonomic nervous system arranged?

Answer 2

Two neurone arrangement (pre and post ganglionic) and an associated ganglion.

Question 3

Where is the sympathetic autonomic outflow from the CNS from?

Answer 3

Segments T1-L2 of the spinal cord. Thoracolumbar outflow.

Question 4

Where are the cell bodies of the sympathetic autonomic outflow from the CNS found?

Answer 4

Cell bodies are within the lateral horn of grey matter of the spinal cord.

Question 5

Where is the parasympathetic autonomic outflow from the CNS from?

Answer 5

Cranial (4 CN’s) and sacral (S2-4) the pelvic splanchnics. Craniosacral outflow.

Question 6

Where are the cell bodies of the parasympathetic autonomic outflow from the CNS found?

Answer 6

As discrete collections of parasympathetic cell bodies (nuclei) in the brainstem, or within the great matter of the spinal cord.

Question 7

What route does the sympathetic innervation to the head and neck take?

Answer 7

Preganglionic nerves from T1 and T2, pass through cervical ganglia, synapse at superior cervical ganglia, postganglionic nerves travel along in a plexus on the external carotid artery to the face and neck (salivary and lacrimal glands), and the internal carotid, through the base of the skull, along the opthalmic artery, CN Va and CN III to the eye (smooth muscle relating to the pupil, lens and eyelid (superior tarsal muscle)).

Question 8

Pathology involving what structures in the chest can cause autonomic dysfunction in the eye and face? What syndrome can these lead to?

Answer 8

Pathology involving the the apex of the lungs (eg pancoast tumour) and internal carotid artery.
Horner’s syndrome.

Question 9

What are the main symptoms of Horner’s syndrome?

Answer 9

Partial ptosis, miosis, anhidrosis.

Question 10

Which cranial nerves carry pre ganglionic parasympathetic fibres from the brainstem to the ganglia in the head and neck?

Answer 10

CN III - oculomotor.
CN VII - facial.
CN IX - glossopharyngeal.
CN X - vagus.

Question 11

Which cranial nerve carries post ganglionic fibres from the ganglia to the target tissue in the head and neck?

Answer 11

CN V - one of the branches of the facial nerve.

Question 12

What parasympathetic nucleus gives rise to the nerve that then joins with the ciliary ganglia which then gives rise to the nerve that innervates the iris sphincter muscle and the ciliary muscle?

Answer 12

Edinger westphal.

Question 13

What are the 4 parasympathetic ganglia of the head and neck?

Answer 13

Ciliary.
Submandibular.
Pterygopalatine.
Otic.

Question 14

What route do the parasympathetic nerves innervating the ciliary muscle take?

Answer 14

Arise form brainstem (edinger westphal), hitch hikes in CN III, synapses at ciliary ganglion, hitch hikes on small branches from CN Va to eye.

Question 15

Where on the oculomotor nerve are the parasympathetic fibres found?

Answer 15

At the edge of the oculomotor nerve.

Question 16

Why do the pupils of both eyes constrict when light is shone into just one?

Answer 16

Light shone in left eye, sensory afferent from left retina carried by CN II, the optic nerve. Carried by some branches that leave CN II to enter the midbrain, which then communicate with the parasympathetic nucleus (EWN) on both the left and right due to the optic chiasm. The parasympathetic fibres from EWN then leave the brainstem, hitch hike on CN III on both the left and right, pass via the ciliary ganglion and reach the sphincter pupillary which constricts. This causes a direct light reflex in the left eye and a consensual light reflex in the right eye.

Question 17

What two main branches of the facial nerve do the preganglionic parasympathetic fibres reach their target tissue by from the petrous temporal bone?

Answer 17

Greater petrosal nerve.
Chorda tympani nerve.
(Both branches of CN V).

Question 18

What two parasympathetic ganglia are associated with the parasympathetic fibres transported with CN VII, the facial nerve?

Answer 18

Pterygopalatine ganglia and submandibular ganglia.

Question 19

Parasympathetics associated with CN VII:
The greater petrosal nerve synapses with the pterygopalatine ganglion, which then gives off branches that innervate what glands?

Answer 19

Lacrimal gland, nasal glands and palatine glands.

Question 20

Why can a lesion to the greater petrous all nerve cause a dry eye?

Answer 20

Carries parasympathetic fibres innervating the lacrimal gland.

Question 21

Parasympathetics associated with CN VII:
The chorda tympani nerve synapses with the submandibular ganglion, which then gives off branches that innervate what glands?

Answer 21

Sublingual gland and submandibular gland.

Question 22

With what ganglia do preganglionic parasympathetic fibres associated with CN IX, the glossopharygeal nerve, synapse with?

Answer 22

Optic ganglion.

Question 23

What route do the parasympathetic fibres associated with CN IX take to the parotid gland?

Answer 23

Preganglionic parasympathetic fibres arise from the brainstem with CN IX, pass through the jugular foramen, with the tympanic nerve, tympanic plexus and lesser petrosal nerve. Synapses with optic ganglion, and postganglionic parasympathetics hitch hike with branch of CN Vc to the parotid gland.

Question 24

Where do preganglionic parasympathetic fibres associated with CN X, the vagus nerve, meet their ganglion?

Answer 24

At or in the target tissue.

Question 25

What structures do parasympathetic fibres associated with CN X innervate?

Answer 25

Glands in the laryngopharynx, glands and smooth muscle of the oesophagus and trachea, heart, smooth muscle and glands within the respiratory and gastrointestinal tract.