The ANS Flashcards
Describe the sympathetic innervations in the head and neck. (6)
Smooth muscle of blood vessels - constrict
Levator palpebrae superioris muscle of eyelid
Dilator pupillae
Sweat glands
Arrector pilli muscles of hair fibres
Decreases secretions from salivary and lacrimal glands.
Describe the parasympathetic innervations in the head and neck. (3)
Sphincter pupillae
Lacrimal glands
Salivary glands
Describe the path of sympathetic nerves from the spinal cord To their target tissue. (5)
Comes from T1 and travels up the sympathetic chain to the superior cervical ganglia where they synapse.
Some branches follow the ECA to the face and neck with sweat glands and blood vessels.
Others follow the ICA into the skull, then the opthalmic artery into the orbit to the lacrimal glands, nasal mucosal glands and muscles of the eye.
Explain the common presentations of Horner’s syndrome. (5)
Pathologies in the apex of the lungs like Pancoast tumours can impinge on the sympathetics on their root from the spine into the skull.
This can lead to:
Miosis (constricted pupil) - dilator pupillae lost
Ptosis - levator palpebrae superioris lost.
Anhydrosis - lack of sweating.
Describe the origination of the parasympathetic portion of the 4 cranial nerves.
III - Edinger Westphal
(VII - superior salivary)
(IX - inferior salivary)
(X - dorsal motor)
Describe the names of the ganglions that the parasympathetics synapse in after hitchhiking on a cranial nerve.
III - cillary
VII - submandibular and pterygopalatine
IX - otic
(X - no named ganglion)
Which cranial nerve do the short post ganglionic parasympathetic fibres hitchhike on?
V Trigeminal
Explain why the concentric light reflex occurs. (7)
Light in left pupil > sensory afferent from left retina (CNII) > some branches leave CNII to enter midbrain, some connect with left and right Edinger Westphal nuclei > parasympathetics leave EWN with CNIII > ciliary ganglion > hitchhikes with Va branches > sphincter pupillae > direct left light reflex, consensual right light reflex.
