Session 6: Autonomic Innervation Flashcards
General target tissues of the autonomic nervous system from cranial nerves from Head & neck.
Glands
Smooth muscle
Cardiac muscle
Where does the parasympathetic nerve fibres arise from?
Called craniosacral outflow.
4 cranial nerves
S2-S4 (pelvic splanchnic)
Where does the sympathetic nerve fibres arise from?
The thoracolumbar outflow
T1-L2
What cranial nerves carry sympathetic nerve fibres?
CN III Oculomotor nerve
CN VII Facial nerve
CN IX Glossopharyngeal nerve
CN X Vagus nerve
Explain the general route the parasympathetics fibres take to reach their target.
Arise from the brainstem
Pre-ganglionic fibres go to synapse in a ganglia
Post-ganglionic fibres travel to target tissue to innervate
Central control of the autonomics.
Hypothalamus
Where does the parasympathetics of the oculomotor nerve arise?
Edinger Westphal nucleus
What carries the parasympathetics that arise from Edinger Westphal nucleus?
Oculomotor nerve
What ganglion does the parasympathetics from the Edinger Westphal nucleus synapse in?
Where can this ganglion be found?
The ciliary ganglion in the bony orbit
What carries the post-ganglionic parasympathetic fibres from the ciliary ganglion?
A branch of the ophthalmic nerve (Va) which is the short ciliary nerve.
What do these post-ganglionic parasympathetic fibres from the Edinger Westphal nucleus innervate?
The sphincter pupillae which is a pupil constrictor
The ciliary muscles controlling the lens
What other nuclei do parasympathetic fibres arise from?
Edinger Westphal (already mentioned)
Superior salivatory nucleus
Inferior salivatory nucleus
Dorsal vagal motor nucleus
What carries the parasympathetic fibres arising from the superior salivatory nucleus?
The greater petrosal nerve which is a branch of the facial nerve.
What do the parasympathetic fibres that are carried by the greater petrosal nerve synapse in?
Where can this ganglion be found?
The pterygopalatine ganglion.
In the pterygopalatine fossa
What are the post-ganglionic parasympathetic fibres of from the pterygopalatine ganglion carried by?
Branches of the maxillary nerve (Vb)
What do these post-ganglionic parasympathetic fibres from the pterygopalatine ganglion innervate?
Lacrimal glands
Nasal cavity
Nasopharynx
Palate
What other parasympathetic fibres arise from the superior salivatory nucleus?
Pre-ganglionic parasympathetic fibres which are carried by the chorda tympani of the facial nerve.
Where do the pre-ganglionic parasympathetic fibres carried by the chorda tympani synapse in?
Where can this ganglion be found?
Submandibular ganglion found inferior to the lingual nerve
What carries the post-ganglionic parasympathetic fibres from the submandibular ganglion?
The mandibular nerve (Vc)
What do the post-ganglionic parasympathetic fibres from the submandibular ganglion innervate?
The submandibular gland
Sublingual salivary glands
What are the pre-ganglionic parasympathetic fibres rising from the inferior salivatory nucleus carried by?
Firstly the tympanic nerve which to thereafter branch into the lesser petrosal nerve.
Both of which are branches of the glossopharyngeal nerve.
What do the pre-ganglionic parasympathetic fibres carried rising from the inferior salivatory nucleus synapse in?
Where can this ganglion be found?
The otic ganglion found in the infratemporal fossa
What are the post-ganglionic parasympathetic fibres from the otic ganglion carried by?
A branch of the mandibular nerve called the auriculotemporal nerve.
What do the post-ganglionic parasympathetic fibres that exit from the otic ganglion innervate?
Parotid gland
What nerve carries the fibres arising from the dorsal vagal motor nucleus?
Vagus nerve
Brief summary of innervation of the parasympathetic fibres of the vagus nerve.
Smooth muscle of the trachea
Bronchi
GI
Heart
All post-ganglionic parasympathetic fibres hitch-hike onto which cranial nerve?
Which is an exception?
Trigeminal nerve CN V
Except for vagus nerve’s post-ganglionic parasympathetic fibres
Parasympathetic response.
Rest and digest:
Pupillary constriction
Accommodation reflex
Glandular secretions (mucous and salivary)
What does the sympathetic nervous system innervate in the head and neck?
Smooth muscle of the vessels
Eye lid (tarsal muscles)
Iris (dilator pupillae)
Sweat glands
Arrector pili muscles
Where does the sympathetic outflow originate from?
The thoracolumbar outflow from the T1-L2.
Originate from the cell bodies of the lateral horn of grey matter of spinal cord.
What are the nerve roots of sympathetic fibres that mainly supply the head and neck?
T1-T2
Parasympathetic fibres hitch-hike on nerves to reach their destination in the head and neck.
What do sympathetic nerve fibres hitch-hike on?
Blood vessels
What are the important ganglion of the sympathetic nerve fibres supplying the head and neck?
Superior cervical ganglion
Middle cervical ganglion
Inferior cervical ganglion
Where can the superior cervical ganglion be found?
Located posteriorly to the carotid artery and anterior to the C1-C4 vertebrae.
What sympathetic nerves exits via the superior cervical ganglion as post-ganglionic sympathetic nerve fibres?
Internal carotid nerve
External carotid nerve
Nerve to pharyngeal plexus
Superior cardiac branch
Nerves to cranial nerves II, III, IV, VI and IX
Gray rami communicantes
Explain the route of the internal carotid nerve.
Travels along the internal carotid artery and branches to form the internal carotid plexus.
The internal carotid artery enters the cranial cavity via the carotid canal. It then travels through the carotid canal in the petrous part of the temporal bone to enter the cavernous sinus.
What do the sympathetic nerves that exit via the superior cervical ganglion innervate?
Structures of the eye
Smooth muscle part of levator palpabrae superioris
Superior tarsal muscles
Sweat glands
Dilator pupillae
Arterial smooth muscle
and many more…
What are the clinical responses to stimulation of the sympathetic nerve fibres of the head and neck?
Dilation of pupil
Sweating
Eye lid retraction
Vasoconstriction
What is the triad of symptoms in Horner’s syndrome?
Partial ptosis
Miosis (constriction of pupil)
Andhydrosis (Decreased sweating)
Explain how partial ptosis come about in Horner’s syndrome.
Due to loss of sympathetic innervation of the smooth muscle part of the levator palpabrae superioris.
Explain why miosis come about in Horner’s syndrome.
Constriction of pupil due to the paralysis of the dilator pupillae and therefore unopposed parasympathetic innervation of the pupil.
Explain why anhydrosis comes about in Horner’s syndrome.
Decreased sweating due to the loss of innervation of the sweat glands of the face.
This happens ipsilateral
Causes of Horner’s syndrome
Spinal cord lesions
Traumatic injury
Pancoast tumour
Explain how a pancoast tumour can cause Horner’s syndrome.
A pancoast syndrome is found in the apex of the lung and can impinge on the sympathetic nerve fibres going to the head and neck.
Explain Adie’s pupil
Ciliary ganglion provides innervation to the sphincter pupillae muscle to constrict the pupil.
If the ciliary ganglion is damaged, there is a loss of innervation to the sphincter pupillae.
This leads to a permanent dilated pupilthat will not constrict in the presence oflight.
Explain the light reflex.
Light is shone into right eye (or left eye, doesn’t matter).
This sends a signal via afferent sensory fibres of the optic nerve.
Some branches leave the CN II to go into the midbrain and then synapse in the pre-tectal nucleus.
The pre-tectal nucleus will then communicate with the Edinger-Westphal nucleus, both left AND right.
The pre-ganglionic parasympathetic fibres from the EDW leave the brainstem with the oculomotor nerve, both left AND right.
The fibres then synapse in both the ciliary ganglia and then travel via the short ciliary nerve (Va) to reach the sphincter pupillae muscle of both eyes.
This leads to constriction of both pupils.
What is the direct light reflex?
When the pupil of the eye which light is shone into constricts.
What is the consensual light reflex?
When the eye that doesn’t have light shone into it constricts.
(Both are physiological responses and should occur)
