ANS of Head and Neck Flashcards
(73 cards)
ANS Control of visceral structures. The visceral targets of the eye include:
Constrictor of smooth m. in iris - PS only –> decrease diameter of pupil
Dilator of smooth m. in iris - SS only –> increase diameter of pupil
ANS of Eye:
Ciliary body smooth m. - PS only –> serves to change the curvature of the lens during the ACCOMMODATION REFLEX
Accommodation Reflex:
Of PS in ciliary body smooth m –> m. contracts –> decreases tension –> lens more convex (fatter) –> accommodation
ANS of Glands - Lacrimal gland:
Secretion of tears to maintain corneal moisture
ANS of Nasal, palatine, submandibular, sublingual, and parotid glands:
Secrete mucus into nasal and oral cavities –> maintain the moisture in nasal and oral cavities
ANS of sweat glands:
Heat dissipation and maintain core temperature
ANS to blood vessels:
Cerebral blood vessels, except those in brain tissue (parenchyma) –> uniform blood flow and oxygenation to the brain; SS control (causes vasoconstriction to decrease blood flow)
ANS of larynx:
Mucus glands in the larynx –> maintain moisture in airways
PS Innervation of Iris (constrictor of pupil) and ciliary body - Preganglionic cell body is in:
Edinger-Westphal nucleus (in brainstem)
PS Innervation of Iris (constrictor of pupil) and ciliary body - Preganglionic fiber follows:
CN III
Preganglionic fiber follows III to:
Ciliary ganglion (behind eyeball) and terminates –> synapses with postgang neurons in ciliary ganglion
The ciliary ganglion is the PS analogue to the:
SS collateral ganglion
PS Innervation of Iris (constrictor of pupil) and ciliary body - POSTganglionic fibers pierce:
Sclera and run forward in the perichordial space –> innervate smooth m. of either constrictor pupil in iris or in ciliary body
Summary Pathway of PS innervation of iris/ciliary body:
Pregang CB in Edinger-Westphal nucleus (brainstem) –> pregang axons follow III to cilliary ganglion –> synapse here with postgang neurons –> postgang pierce sclera –> run forward in perichordial space –> innervate smooth m. of constrictor pupil or in ciliary body
Activation of PS in sphincter pupil causes:
Contraction of sphincter –> narrowing of pupil (MIOSIS). This action sharpens the visual image by allowing LESS light to come into the retina
Activation of PS in ciliary body causes:
Contraction of ciliary smooth m. –> LESSENS the tension in the suspensory ligament of the lens –> thickens the lens curvature (enhances its convexity) during accommodation - refocusing of the image on the retina
SS innervation of iris (dilator m): SS Preganglionic neuron:
In intermediolateral cell column at T1-T2 spinal cord levels
SS innervation of iris (dilator m): SS pregang. axons follows:
The white communicating rami (WCR) and enters the SS chain ganglia –> ascends in SS trunk to superior cervical ganglion (SCG) –> ends by synapsing w postgang neurons in SCG
SS innervation of iris (dilator m): SS postgang fibers follow:
Blood vessels (internal carotid a) –> then long ciliary n. to the eyeball –> pierces sclera –> runs forward (in perichordial space) to iris –> innervates pupillary dilator
Summary Pathway of SS innervation of iris:
SS pregang neurons in intermediolateral cell column at T1-T2 –> pregang axons follow WCR –> enter SS chain ganglia –> ascends in trunk until the superior cervical ganglion –> synapses here with postgang neurons –> postgang fibers follow internal carotid a –> then follow long ciliary n –> pierce sclera –> run forward thru perichordial space) –> innervates pupillary dilator
Activation of SS causes:
Contraction of radially disposed muscle fibers of dilator which increases the diameter of pupil (MYADRISIS) –> allows more light to fall onto retina. This action is seen during a stress reaction or during dark adaptation
SS fibers also innervate the ______. Lesioning of these SS fibers brings about _______.
Superior tarsal (smooth) muscle in the upper eyelid, partial ptosis
Location of the superior cervical ganglion:
Between vertebrae C1 and C2
Location of the middle cervical ganglion:
About the level of C6