ANS of Head and Neck Flashcards
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
Location of the inferior (stellate) cervical ganglion:
Anterior to neck of the 1st rib
Unilateral cranial nerve III (oculomotor) lesion:
This carries PS fibers to iris and ciliary body. Sxs:
- ipsilateral (same side of lesion) MYADRISIS - since PS is damaged, SS takes over the the pupil is very large
- loss of DIRECT light reflex (when the light is shone on lesion’s side) - ipsilateral pupil does not constrict
- loss of ipsilateral accommodation reflex
Horner’s syndrome:
Condition resulting from destruction of central SS pathways or the superior cervical ganglion. Sxs (all ipsilateral to lesion) are:
- MIOSIS - lack of SS control causes PS to take over, pupil is very small
- Partial ptosis
- Dry skin - lack of sweating
- Flushed skin - due to vasodilation bc of lack of SS vasomotor control
Why not full ptosis with Horner’s syndrome?
Still have levator palpebrae superioris innervated by III to hold it up
ANS Innervation of lacrimal, nasal, oral, and salivary glands:
Volume secretion of tears and mucus is mainly controlled by PS
ANS Innervation of lacrimal, nasal, oral, and salivary glands: PS preganglionic CB in:
Superior salivatory nucleus (level of caudal pons)
ANS Innervation of lacrimal, nasal, oral, and salivary glands: Pregang fibers leave CNS with:
CN VII and join –> greater petrosal n. and n. of pterygoid canal
ANS Innervation of lacrimal, nasal, oral, and salivary glands: Pregang fibers synapse with postgang fibers in:
Pterygopalatine ganglion
ANS Innervation of lacrimal, nasal, oral, and salivary glands: After PT ganglion, Postgang fibers follow:
Branches of maxillary n (V2), zygomatic, and lacrimal n. –> lacrimal gland. (Other branches go to mucus glands in nasal and oral cavities)
Summary of ANS Innervation of lacrimal, nasal, oral, and salivary glands:
PS pregang CB in superior salivatory nucleus (level of caudal pons) –> PS pregang fibers leave CNS with VII –> join greater petrosal n. and n. to pterygoid canal –> synapse with postgang fibers in pterygopalatine ganglion –> postgang fibers follow branches of V2, zygomatic, and lacrimal nn. to lacrimal gland
Activation of PS to lacrimal, nasal, oral and salivory glands causes:
Increased secretion of tears from lacrimal gland and mucus from nasal and oral glands. This can occur under conditions of distress and sadness
PS Innervation of submandibular and sublingual glands: PS pregang CB in:
Superior salivatory nucleus (level of caudal pons)
PS Innervation of submandibular and sublingual glands: Pregang fibers follow:
CN VII –> then follow chorda tympani (passes close to tympanic membrane in middle ear - hence, lingual branch of mandibular (V3) to submandibular ganglion
PS Innervation of submandibular and sublingual glands: Pregang fibers synapse with postgang in:
Submandibular ganglion
PS Innervation of submandibular and sublingual glands: Postgang fibers leave ganglion and innervate:
Submandibular or sublingual gland
Summary of PS Innervation of submandibular and sublingual glands:
Pregang CB in superior salivatory ganglion –> follow VII –> then follow chorda tympani –> jump on lingual n. (V3) submandibular ganglion –> synapses here with postganglionic neurons –> postgang fibers leave ganglion –> innervate sublingual or submandibular glands
PS Activation of submandibular and sublingual glands causes:
Increased saliva secretion from the salivary glands (includes from parotid) and increased blood flow within the glands –> increase in blood flow causes a greater metabolic demand in the gland due to its increased secretion. This occurs when food is put into the mouth –> starts the process of digestion, also occurs after olfactory stimuli
PS innervation of parotid gland: PS pregang CB:
INFERIOR salivatory nucleus (at rostral medulla level)
PS innervation of parotid gland: PS pregang axon leaves CNS with:
Tympanic branch of CN IX (glossopharyngeal) –> then passes thru tympanic plexus –> joins LESSOR petrosal n.
PS innervation of parotid gland: Pregang then synapses with postgang neurons in:
Otic ganglion (in the IT fossa on the medial side of V3)
PS innervation of parotid gland: Postgang leaves otic ganglion and joins:
Auriculotemporal branch of mandibular n (V3) –> innervates parotid gland
Summary of PS innervation of parotid gland:
PS pregang CB are in the inferior salivatory nucleus (at rostral medulla level) –> leave CNS with tympanic branch of CN iX –> goes thru tympanic plexus –> joins the Lesser petrosal n. –> synapses with postgang neurons in otic ganglion –> leaves otic ganglion and joins the auriculotemporal n. (branch of V3) –> innervates the parotid gland
PS activation to parotid gland causes:
Increased salivary secretion and blood floow to the gland –> start of digestion
SS innervation of ALL head and neck salivary glands:
Whereas PS controls the glandular volume secretion, SS has the ability to inhibit such secretions for all glands in head and neck (Ex: during stress, one’s mouth gets dry and swallowing becomes harder
SS innervation of ALL head and neck salivary glands: SS pregang CB located in:
Intermediolateral cell column at T1-T2 spinal levels
SS innervation of ALL head and neck salivary glands: SS pregang fibers enter:
SS chain ganglia with WCR –> ascend (in SS trunk) up to superior cervical ganglion
SS innervation of ALL head and neck salivary glands: SS pregang fibers synapse with postgang fibers in:
Superior cervical ganglion
SS innervation of ALL head and neck salivary glands: SS postgang fibers follow:
The carotid plexuses (ANS fiber network around the common, external, and internal carotid arteries and their branches) –> target glands
Summary of SS innervation of ALL head and neck salivary glands:
SS pregang CB in interomediolateral cell column of T1-T2 –> go into SS chain ganglia with WCR –> ascend in SS trunk –> superior cervical ganglion –> synapse with postgang fibers here –> follow the carotid plexus –> innervate target glands
SS activation of salivary glands in head and neck causes:
Cessation of secretion and decreased blood flow to the glands
Unilateral intracranial VII lesion (proximal to stylomastoid foramen):
- Ispilateral dry eye - emergency, cornea is prone to ulcerations
- Decreased salivary secretion (BUT salivary secretion is normal in ipsilateral parotid gland and all contralateral salivary glands)
- Regenrating PS fibers may be diverted to LACRIMAL gland –> Crocodile tears (tearing while eating)
Penetrating wound to parotid gland:
- Regenerating PS fibers to parotid may be diverted instead to SWEAT glands in overlaying skin
- Salivation stimulus may produce sweating from a patch of skin over the gland
FREY’s SYNDROME
ANS innervation of the head and neck Blood Vessels:
Blood vessels of head and neck are innervated ONLY by SS fibers
ANS innervation of the head and neck Blood Vessels: SS pregang cell bodies in:
Interomediolateral cell column at T1-T3 spinal cord levels
ANS innervation of the head and neck Blood Vessels: SS pregang fibers enter:
SS chain ganglia and terminate on SS postgang in the superior cervical and inferior (stellate) ganglia
ANS innervation of the head and neck Blood Vessels: SS postgang fibers follow:
The carotid plexus and innervate smooth muscle around major arterial branches
SS postganglionic fibers innervate smooth muscle around major arterial branches including those on the brain surfaces (conducting vessels) but what loses ANS innervation?
Penetrating vessels (parenchymal) vessels. Parenchymal reacting arterioles are locally controlled
SS activation for blood vessels causes:
Vasoconstriction and reduction in blood flow in the conduction branches
The intracerebral (parenchymal) vessels are controlled by both:
Cerebral autoregulation and by a local control at the level of the blood vessel wall.
Brain autoregulation is dependent on:
Blood borne concetration of CO2, which increased CO2 levels enhancing vasodilation and blood flow (HYPERCAPNIA - cerebral vessels dilate to ensure appropriate delivery of O2 to the brain)
Locally, at the level of the endothelial wall:
NO (vasodilator) and endothelin (vasoconstrictor produced by endothelium) maintain appropriate local smooth m. tone in the reacting arteries to control blood flow through the capillary bed. This ensures a constant delivery of blood flow and metabolites to the brain. Also, angiotensin and purines (adenosine, ATP) play a role in regulating cerebral blood flow
ANS Innervation of blood vessels and glands in Larynx: PS pregang CB in:
DORSAL MOTOR NUCLEUS of CN X (mid-medulla level)
ANS Innervation of blood vessels and glands in Larynx: PS pregang fiber follows:
Laryngeal branch of X –> pierces wall of larynx –> synapses on PS postgang neurons
ANS Innervation of blood vessels and glands in Larynx: PS postgang neurons in:
Terminal ganglia within the mucosa of larynx
PS activation in blood vessels/glands in larynx causes:
Increased mucus secretion and gland vasodilator effects –> moistens and warms the airways
ANS Innervation of blood vessels and glands in Larynx: SS pregang CB in:
Interomediolateral cell column at T1-T2
ANS Innervation of blood vessels and glands in Larynx: SS pregang fibers then ascend:
In the SS trunk up the the MIDDLE cervical ganglion –> synapses on postgang neurons
ANS Innervation of blood vessels and glands in Larynx: SS postgang fibers follow:
External carotid artery to larynx and –> innervates either mucus glands or blood vessels
SS activation in blood vessels and glands of larynx causes:
Decreased mucus secretion and vasoconstrictor effects (just opposite to those of PS)
