ANS of head and neck Flashcards
Where does the autonomic nervous system originate from?
the peripheral nervous system
Where is the central control of ANS?
the hypothalamus
What does the ANS affect?
internal organs and glands
- body functions that are not under conscious control (smooth muscle in viscera)
- eye, salivary and lacrimal glands
What is the main overall role of the ANS?
maintaining and regulating the body internal enviornment
What is the main functions of sypathetic nervous system?
- pupillary dilation
- assists eyelid retraction
- vaso-constriction
- sweating
What are the main functions of parasympathetic nervous system?
- smooth muscle of iris (sphincter pupillae)
- muscles in cilliary body (control thickness of lens)
- lacrimal glands
- salivary and mucosal glands
- smooth muscles of resp and GI tract
Where does the sympathetic outflow to the whole body arise from?
the thoracolumbar portion (T1-L2)
Where are the cell bodies found?
in the lateral horn of the grey matter
Where does the parasympathetic outflow to the whole body arise from?
-craniosacral portion
cranial (4 cranial nerves)
sacral (s2,3,4) - pelvic splanchnics
At what spinal level do pre-ganglionic sympathetics destined for the head and neck arise from?
T1/2
What do the pre-ganglionic sympathetics have to do before they can synapse?
they must ascend the sympathetic chain to reach the neck before synapsing
Where do they synapse?
in the superior cervical ganglion
What is in the superior cervical ganglion?
- located opposite the 2nd and 3rd cervical vertebrae
- cell bodies of the post-ganglionic sympathetic nerve
What happens after the sympathetics have synapsed?
They join to the common cartoid artery and follow its 2 branches
What follows the ECA?
the nerves that have branches to distribute across the face.g. sweat glands and hair follicles
What follows the ICA?
the nerves that need to supply the eye (into the orbit)
What branch of the ICA will the nerve follow to get to the orbit?
the opthalmic branch of the ICA - can then supply eye lid and pupil
What is myosis?
contraction of the pupil
What does “unopposed pasrasympathetics” mean?
normally have sympathetic and parasympathetic to balance out - if you lose sympathetic innervation, you get “unopposed parasympathetic” - causing it to constrict
What does pathology in the apex of the lung or the CCA cause?
autonomic dysfunction in the eye and face
What would a person with a tumour in the apex of their lung present with and why?
- compression of the CCA and therefore the cranial nerves
- Partial ptosis and myosis and anhydrous (lack of sweating)
- unapposed parasympathetics causing contraction of the eye
Why only partial ptosis?
most of LPS works (as result of oculomotor nerve) but a part of it uses sympathetic innervation hence only partial
What are the triad of symptoms caused by?
horners syndrome - think about neck and chest
What cranial nerves carry parasympathetics out from the brain stem?
oculomotor
vagus
facial
glossopharyngeal
Where do parasympathetics arise from?
2 regions of the spinal cord (cranial region and sacral region)
Where does the parasympathetic innervation to the head and neck arise from?
parasympathetic nuclei
What is parasympathetic nuclei?
collections of pre ganglionic parasympathetic nerve cell bodies
What is different about the parasympathetic preganglionic nerves compared to sympathetic preganglionic?
they are longer and travel a longer distance before reaching their associated ganglia as the ganglia lie closer to their effector tissues - note that once they synapse within their ganglia, their post ganglionic neurone is comparatively shorter
What are the parasympathetic ganglia?
4 discrete ganglia (unlike the chain of ganglia with the sympathetics)
- ciliary
- submandibular
- pterygopalatine
- otic
How do the parasympathetics reach the ganglia?
they hitch hike on CN’s 3,7,9,10
What happens once the parasympathetics reach the ganglia?
they ALL hitch hike onto the branches of the trigeminal nerve
What are the 4 parasympathetic nuclei?
- edinger westphal!!!!!!
- superior salivary
- inferior salivary
- dorsal motor
What are the target tissues of the parasympathetics?
- sphincter pupillae (pupil constrictor)
- cilliary muscle (controls lens)
- lacrimal gland
- mucosal glands (nasal, resp, oral mucosa)
- salivary glands
What is the rough of parasympathetics on CN III?
- parasympathetic arise from EWN (nucleus)
- parasympathetic fibres emerge with CN III fibres
- synapses at the ciliary ganglion (at the back of the orbit) where the parasympathetics hitch hike onto CN Va
What does the parasympathetics do to the eye?
- acts on the ciliary muscle to alter the shape of the lens
- acts on sphincter pupillae muscle to constrict the pupil
What nerve senses light?
the optic nerve - sends signals to the optic chiasm and the optic tract
DRAW OUT THE PUPILLARY LIGHT REFLEX
-why do both of the eyes constrict when light is shone in 1 of the eyes
What is anisocoria?
a condition characterised by an unequal size of the eyes pupils
What branches of the facial nerve do the parasympathetics reach their targets via?
-chorda tympani and greater petrosal
Where are the ganglia for the facial nerves parasympathetics?
- pterygopalatine ganglia (pterygopalatine fossa)
- submandibular ganglia
After synapsing, where do the post-ganglionic parasympathetics go?
-run with the distal branches of the trigeminal (lingual) nerve
What else does the chord tympani supply?
-taste to the anterior 2/3 of the tongue
its ganglia is sensory so will be found in the geniculate ganglion
Which of the branches of CN IX does the parasympathetic run along?
-tympanic nerve (which supplies the middle ear)
Where does the parasympathetics go after running with the tympanic nerve?
the parasympathetics exit the middle ear as the lesser petrosal nerve
Where does the lesser petrosal nerve synapse?
in the otic ganglion in the infra temporal fossa
Where do the post-ganglionic parasympathetics go?
hitch hike on the CN Vc -auriculotemporal nerve to the parotid gland
Where do CNX pre-ganglionic parasympathetics run?
within CNX and its branches
Where are the ganglia?
at or in the target tissue
What is the target tissue for parasympathetics on CNX?
- mucosal glands in pharynx/larynx
- smooth muscle of oesophagus and trachea
- smooth muscle and mucosal glands within rest of respiratory and GI tract
- Heart
