The Autonomic Nervous System Flashcards
From where do the sympathetic nerves arise?
From the thoracolumbar spinal cord
From where do the parasympatheic nerves arise?
From the brainstem (cranial) and the sacral part of the spinal cord (S2-S4)
What are the features of the sympathiec nerves in the head?
The smooth muscles of the eyelids- tarsal muscle that acts to retract the eyelid and keeps the eyelid wide and the iris (dilator papillae) that will act to dilate the pupil as much as possible. Also activates the sweat glands, and the arrectaro pilli muscles adn decreases secretions from the salviary and lacrimal glands
What are the features of the parasympathic system in the head and neck?
Smooth muscle of irsi the spincter pupillae and the ciliary body are activated, the lacrimal glands and the salivary and the mucosal glands are activated
What is the route for the sympatheic nerves to the head?
Arise from the spinal cord, go to the sympatheic chain, and then to the cervical ganglion, and then hitchikes onto blood vessels to the target tissues
From where do the nerves going to the head arise?
Begin in the T1 and T2 region of the spinal cord
What are the most intresting structure in the sypatheic chain regarding the head and neck?
The superior, middle and inferior cervical ganglia
What are some of the features of the superior cervical ganaglion?
Located posteriorly to the cartoid atery and anterior to the C1-C4 vertebrae.
Which blood vessels do the sympathiec fibres hitchike along?
The internal cartoid nerve hitchkikes along the internal carotid artery, and forms a number of branches called the internal cartoid plexus, and then the external carotid nerve that hitchkikes along the common and external cartoid artery
What can cause Horners Snydrome?
Sympatheic fibres can be stretched and damaged along their course
What are the three key features of Horners Syndrome?
Partail Ptosis, Misosis and Anhydrosis
Why do you see partial Ptsosis in Horners Syndrome?
There is paralysis of the superior tarsal msucle
What is misosis and why do you see it in horners syndrome?
This is constriction of the pupuk, and due to the paralsysis of the dilator pupillae
Why do you see anhydrosis in hroners scyndrome?
There is a loss of innervation to the sweat glands of the face
What can cause horners syndrome?
Spinal cord lesions, trauma, a pancoast tumour, and if neck pain there could be some form of cartoid atery dissection