Cranial nerves: parasympathetic function Flashcards
What cranial nerves have a parasympathetic function|?
3, 7, 9 and 10
What do sympathetic preganglionic neurons enter the sympathetic trunk via?
White ramus communicantes (WRC)
What do postanganglionic sympathetic fibres exit the sympathetic cord via?
Form the grey ramus communicantes that joins a spinal nerve in which it is distributed to the body wall
What does each sympathetic trunk extend between?
The atlas and coccyx
What do the 2 sympathetic trunks fuse to form?
The ganglion impar (opposite the coccyx)
What are the sympathetic cervical ganglia?
- Superior (C1-4)
- Middle (C5-6)
- Inferior (C7-8) cervical ganglia
- Stellate ganglion(cervicothoracic) -> Inferior cervical + T1
What make up the cervicothoracic/stellate ganglion?
C7-T1 cervical ganglia (inferior cervical + T1)
Where do sympathetics reaching the eye originate?
T1-2 ciliospinal centre
Where do sympathetic pre-ganglionic neurons to the eye synapse?
Superior cervical ganglion
What do post-gnaglionic sympathetic fibres to the eyes form a plexus around?
Internal carotid artery (enter into cranial cavity through this road - they then hitchhike with cranial nerves and their branches)
Sympathetics which go to Dilator papilla muscle are carried by what nerve?
Nasociliary nerve -> long ciliary nerve
What is the nasociliary nerve a branch of?
Opthalmic nerve
What does the oculomotor nerve supply?
Levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, and inferior oblique muscles
What are the symptoms of HOrner’s syndrome?
- Ptosis - drooping of upper eyelid
- Pupillary constriction (miosis)
- Anhydrosis (lack of sweating)
- Flushing of the face
Results of unapposed parasympathetic activity
How many neurons are in the parasympathetic chain?
2 neuron chain
Where do the pre-ganglionic neurons in the CNS synapse?
In a ganglion with a post-ganglionic neuron
Where are the parasympathetic ganglia located?
Close to the organ -> long pre-synaptic fibres and short post-synaptic fibres
What cranial nerves have parasympathetic output?
- CN III - Oculomotor
- CN VII - Facial
- CN IX - Glossopharyngeal
- CN X - Vagus
What are the functions of the parasympathetic fibres from cranial nerves?
- Salivary glands
- Lacrimal glands
- Certain structures in eye
What is the nucelus for the oculomotor nerve?
- Autonomic nucleus (Edinger-Westphall)
- Midbrain
Where does the autonomic nucleus receive afferents from?
- Receives afferents from cortex and pretectal nucleus, bilaterally
Where does oculomotor nerve travel?
- Lateral wall of cavernous sinus (with motor fibres)
- Pass through superior orbital fissure and enter orbit
In the orbit what does the oculomotor nerve divide into?
- Superior and inferior divisions pass through common tendinous ring of Zinn but only inferior division contain parasympathetics
What does the superior ramus of the oculomotor nerve contain?
Motor fibres from oculomotor nucleus + sympathetic fibres from superior cervical ganglion to levator palpebra superioris
What does the inferior ramus of the oculomotor nerve contain?
Parasympathetic fibres
Where do parasympathetic fibres of the oculomotor nerve synapse?
Ciliary ganglion
What do postsynaptic oculomotor nerve fibres join?
Short ciliary nerves
What do short ciliary nerves run alongside?
Long ciliary nerves and ciliary artery
What does the oculomotor nerve supply?
- Ciliary muscle
- Sphincter pupilla
What is the lamina cribrosa sclerae?
Mesh like structure on the posterior aspect of eyeball around optic nerve. Arteries and veins pierce this area
What reflex can test the function of the oculomotor nerve?
Light reflex
What is the consensual light reflex?
Light that is directed in one eye produces pupil constriction in both eyes
What is the pretectal nucleus connected to and how does this relate to the consensual light reflex ?
- Certain optic nerve fibres terminate on pretectal nucleus
- Pretectal nucleus then connects to parasympathetic nucleus of oculomotor (edinger-Westphal) on both sides
- Allows for constiction in both eyes by parasympathetic fibres reaching both ciliary ganglia and both short ciliary nerves
- Will cause pupillary constrictor muscle to contract on both sides
What does injury to the oculomotor nerve result in?
- No parasympathetic input for pupil constriction -> dilated pupil
- Loss of motor innervation to levator palpebrae superioris -> Ptosis
- Loss of motor innervation to extraocular muscles except superior oblique (trochlear nerve) and lateral rectus (abducent nerve) -> eye turns downwards and outwards
Where do the parasympathetic secretorymotor fibres of the facial nerve go to?
- Lacrimal gland
- Glands in nasal and oral cavities
- Submandibular and sublingual salivary glands
Where do the parasympathetic fibres of the facial nerve originate?
Superior salivatory nucleus in pons
Where does the facial nerve leave the brainstem?
Pontocerebellar angle
What nerve contains sensory and parasympathetic fibres of the facial nerve?
Nervus Intermedius
What does the facial nerve give off at its genu?
Greater petrosal nerve
What does the greater petrosal nerve join with to make the nerve of the pterygoid canal?
Deep petrosal nerve (joins in foramen lacerum)
Where do the nerve of the pterygoid canal parasympathetic fibres synapse?
Pterygopalatine ganglion
What nerves do the post-ganglionic parasympathetics of the facial nerve join?
The zygomtic branch of the maxillary and the lacrimal branch of the opthalmic
What ganglion is irrated in hay fever?
Pterygopalatine ganglion
What nerve carries the parasympathetic, secretomotor supply to the submandibular and sublingual glands?
Lingual nerve (branch of mandibular) carries the parasympathetic facial nerve fibres. Submandibular ganglion hangs from it
What gland(s) does the facial nerve supply?
Submandibular and sublingual
What is the glossopharyngeal parasympathetic nucleus called?
Inferior salvitory nucleus
Where is the inferior salvitory nucleus located?
Medulla
What does the glossopharyngeal nerve exit the cranial cavity via?
Jugular foramen
Where does the glossopharyngeal nerve give off its tympanic branch?
Inferior to the jugular foramen
What does the tympanic branch enter the middle ear cavity through?
Inferior tympanic caniliculus - forms tympanic plexus in tympanic cavity
What is the lesser petrosal nerve a branch of?
Tympanic plexus
What does the lesser petrosal nerve synapse with?
Post-ganglionic fibres at otic ganglion which make parotid branches of auriculotemporal nerve (CN V3)
What is the parasympathetic nucleus of the vagus?
Dorsal nucleus of vagus (not shared with any other cranial nerve) located in medulla