Autonomics and the cervical plexus Flashcards
From where is all sympathetic outflow to the head and neck?
T1
From exiting T1, describe how sympathetic fibres reach their target tissues
- They enter the sympathetic trunk and travel up the to superior cervical ganglion (top one).
- In here they synapse
- The post ganglionic fibres wind around the carotid arteries.
- The fibres follow the external carotid arteries to the sweat glands and blood vessels of the head and neck
- The fibres also follow the internal carotid artery, then opthalmic artery, the end of CN III and a small amount of Va to get to effector tissues in the eye
What effector tissues do sympathetic fibres innervate in the eye?
- Superior tarsal muscle (opens eye)- via jumping onto the end of the occulomotor nerve
- The dilator pupillae muscle (dilated pupil) - via jumping onto the end of the opthalmic nerve (Va)
- The blood vessels and sweat glands around it
What is horners syndrome? How may it occur?
Interruption of the sympathetic innervation to the head and neck. This may be due to impingment of fibres by pancose tumours, carotid artery aneurysm or dissection.
Describe and explain 3 symptoms of horners syndrome
- Partial ptosis: superior tarsal muscle looses innervation but occulomtor nerve can still supply levator palpebrae superioris to open the eye
- myosis: constricted pupil due to innervation to dilator pupillae being lost
- anhydrosis: lack of sweating on one side of the face
Give a brief overview of how parasympathetic fibres reach effector tissues in the head and neck
- They arise from one of 4 nuclei in the brain
- They start travelling on CN 3,7,9 or 10
- They then synapse at somepoint along that nerve
- Then they hitch hike onto branches of the trigeminal nerve to reach effector tissues
Which nucleus do parasympathetics going to the oculomotor nerve arise from?
Edinger westphal nucleus
Where do preganglion parasympathetic fibres on the oculomotor nerve synapse?
The cillary ganglion
Which nerve do post cillary ganglion parasympathetics travel on it and what effector tissues do they innervate?
A small branch of the opthalmic nerve.
They constrict the pupil and lens
What is the consensual light reflex?
- Light is detected by one eye
- optic nerve stimulated the edinger westphal nucleus
- this doesnt just tell the ipsilateral occulomotor nerve to cause pupil constriction but both of them
- Therefor light detected in one eye cause pupil constriction in both eyes
Describe the path of parasympathetics within the facial nerve (2 branchs, 2 ganglion and 4 effector tissues)
- Arise from brain stem (dont need to know nucleus name)
- The fibres pass through the genticulate gangilion
- Some follow the greater petrosal branch of the facial nerve and then synapse at pterygopalatine ganglion and then follow trigeminal branches to the lacrimal gland and nasal and oral mucosal glands
- Others carry on and follow the chordae tympani branch of the facial nerve and synapse at the submandibular ganglion and jump onto trigeminal branches to the submandibular and sublingual salivary glands
What is the function of the other, non-autonomic, nerve fibres following the chordae tympani branch of the facial nerve?
Taste to the anterior 2/3 of the tongue
Describe the path of the parasympathetic nerve fibres running through the glossopharyngeal nerve (1 branch, 1 ganglion, 1 effector tissue)
- follow glossopharyngeal nerve through the jugular foramen
- It then follows the tympanic nerve branch
- Then it follows the less petrosal nerve branch
- and synapses at the otic ganglion
- follows branches of Vc to get to parotid gland
Describe the path of parasympathetics that travel on the vagus nerve
Pre ganglionic fibres travel with vagus nerve into the thorax and synapse at ganglia on/ in effector tissues. It doesnt ever follow a trigeminal nerve branch.
What nerve roots contribute to the cervical plexus and where is the cervical plexus located?
C1-4 and in the posterior triangle of the neck, deep to SCM and ontop of scalene medius and levator scapulae muscle
