Lecture 9-ANS Flashcards
What is the sympathetic outflow from the CNS called and where does it emerge from?
- thoracolumbar outflow
- T1-L2
What is the parasympathetic outflow from the CNS called and where does it emerge from?
- craniosacral outflow
- cranial outflow - 4 CNS
- sacreal outflow - S2-4
What do the sympathetics innervate?
- SM of blood vessels, tarsal muscle in eyelid and dilator pupillae in irs
- sweat glands
- arrector pili muscles (hair follicles)
- decreased secretions from salivary and lacrimal glands
What do the parasympathetics innervate?
- sphincter pupillae is iris and ciliary body
- lacrimal glands
- salivary and mucosal glands
How do the sympathetics reach the head and neck structures?
By hitch-hiking with blood vessels
Why can a pancoast tumour interrupt the sympathetic outflow to the eye?
In the chest when the fibres leave the thoracolumbar outflow, they are close to the lung apex. A pancoast tumour can interrupt these fibres at the lung apex
What are the symptoms of Horner’s syndrome?
- partial ptosis (not full because still have CN III)
- anhydrosis
- miosis (constricted pupil)
Where is the ganglia of the sympathetic innervation to the head and neck?
Cervical portion of the sympathetic chain (superior cervical ganglia)
Describe the general course of the parasympathetic innervation to the head and neck
Arise from parasympathetic nuclei in the brainstem -> hitch-hike on to one of the 4 CNs -> ganglia -> hitch-hike on branches of CN V -> target tissues
Which four CNs do the parasympathetics hitch-hike onto?
CN III, VII, IX and X
Describe the course of the parasympathetics of the oculomotor nerve
Edinger-Westphal nucleus in brainstem -> parasympathetics hitch-hike onto CN III fibres -> ciliary ganglion -> post-ganglionic branches hitch-hike on small branches from CN Va -> ciliary body and sphincter pupillae
Describe the light reflex if light is shone into the left pupil
Light in left pupil -> sensory afferent from left retina (CN II) -> some branches leave CN II to enter midbrain -> EDW nuclei (left and right) -> parasympathetic fibres from EDW nuclei leave brainstem -> hitch-hike on CN III (left and right) -> pass via ciliary ganglion -> reach sphincter pupillae -> direct light reflex in left eye and consensual light reflex in right eye
Describe the course of the parasympathetics hitch-hiking with the facial nerve that innervate the lacrimal, nasal and oral mucosal glands
Facial nerve from brainstem with hitch-hiking pre-ganglionic parasympathetics -> into petrous part of temporal bone -> geniculate ganglion -> greater petrosal nerve leaves -> pterygopalatine fossa in skull -> pterygopalatine ganglion -> post-ganglionic parasympathetics hitch-hike onto CN V -> lacrimal, nasal and oral mucosal glands
Describe the course of the parasympathetics hitch-hiking with the facial nerve that innervate the submandibular, sublingual, salivary glands
Facial nerve from brainstem with hitch-hiking parasympathetics -> petrous part of temporal bone -> join chorda tympani nerve -> crosses through middle ear cavity -> exits via base of skull -> submandibular ganglion -> post-ganglionic hitch-hikes onto CN V -> submandibular, sublingual and salivary glands
Describe the course of the parasympathetics running with the glossopharyngeal nerve
Pre-ganglionic from brainstem with CN IX -> jugular foramen -> tympanic nerve (branch of CN IX) - sensory to middle ear -> tympanic plexus -> lesser petrosal nerve -> foramen ovale -> otic ganglion -> post-ganglionic fibres hitch-hike with CN Vc -> parotid gland
