Exam 1: ANS and Cranial Nerves

Danny - Fall 2023

Sympathetic nerve fibers location

Sympathetic nerve fibers location

T1 to L2 or L3

Parasympathetic nerve fibers location

CN III, VII, IX, X

S2 through S4

Ganglia location and length in sympathetic

near vertebral column

shorter preganglionic fibers

Ganglia location and length in parasympathetic

within effector organ

longer preganglionic fibers

How does preganglionic fibers leave the spinal cord in the sympathetic nervous system?

through ventral nerve roots and goes to spinal nerves

Where do the postganglionic cell bodies go in the sympathetic nervous system?

sympathetic chain or plexuses

What are the three plexuses?

celiac

superior mesenteric

inferior mesenteric

Preganglionic nerve fibers release what in both systems?

acetylcholine

Postganglionic nerve fibers release what in sympathetic?

norepinephrine/epinephrine

Sympathetic System responses

Blood glucose increase

sweating increase

heart rate increase

inhibit insulin

vasodilation

Sections of paravertebral (sympathetic chain)

superior cervical (C1-C4)

middle cervical (C5-C6)

inferior cervical (C7)

Which plexus does glucose production and release and slows digestion?

celiac

Which plexus does intestinal vasoconstriction?

superior mesenteric

Which plexus does bladder relaxation, ejaculation, and intestinal vasoconstriction?

inferior mesenteric

Sympathetic system lesions cause?

peripheral autonomic failure

autonomic neuropathies

horner’s syndrome

Symptoms of horner’s syndrome

ptosis (eye-drooping)

miosis (constriction of pupil)

damage to Levator Palpebrae Superioris and Radial iris fibers

Where are preganglionic cell bodies in parasympathetic?

CN III, VII, IX, X

S2-S4

Where are postganglionic cell bodies in parasympathetic?

ganglia located near innervat structures

Alimentary canal

What do postganglionic nerve fibers release in parasympathetic?

acetylcholine

Where do afferent sensory fibers enter the brain and terminate?

Enter through Pons

Terminate at Trigeminal Sensory Nucleus

Where do proprioceptive fibers enter the brain and terminate?

Enter through vestibulocochlear nerve

Terminate in vestibular and cochlear nuclei (medulla)

Where do visceral fibers terminate?

nucleus solitarius (medulla)

What does the somatic efferent cell column do?

runs on the midline along the brainstem and sends motor fibers to CN III, IV, VI, and XII

What does the Branchiomotor Cell Column do?

runs on the striatal muscles from pharyngeal arches and sends motor fibers to CN V, VII, IX, X, XI

What does the Parasympathetic cell column do?

runs along axons and sends parasympathetic fibers to CN III, VII, IX, X

CN I

Origin

Termination

Function

Innervation

Olfactory I

Forebrain

Smell

Olfactory Epithelium

CN II

Origin

Termination

Function

Innervation

Optic II

Forebrain

Lateral Geniculate Nucleus

Vision: pupillary light reflex

Retina

CN III

Cell Bodies (M and P)

Function

Innervation

Oculomotor

M: oculomotor nucleus

P: Edinger-Westphal nucleus

Eyeball movement, pupil constriction and accomodation

S/I/M rectus muscles, inferior oblique muscle, levator palpebrae superioris, sphincter pupillae and ciliary muscles

CN IV

Cell Bodies

Components

Function

Innervation

Trochlear

Trochlear nucleus

Motor

Eye movement

Superior oblique muscle

Ptosis, unresponsive pupil dilation and inability to move eye upward, downward, or medially

Symptoms of CN III lesions

diplopia (double vision) when looking medially and downwards

Symptoms of CN IV lesions

CN V

Cell bodies (M and S)

Function

Innervation (M and S)

Trigeminal

M: trigeminal motor nucleus

S: trigeminal sensory nucleus

open and close mouth, tension on tympanic membrane, general sensation, corneal reflex, cough/sneeze reflex, jaw jerk reflex

S: face, scalp, cornea, nasal/oral cavities, dura mater

M: Mastication; tensor tympani

What do CN V lesions cause?

Herpes Zoster

Syringobulbia

CN VI

Cell bodies

Function

Innervation

Abducens

Abducens nucleus

lateral eye movement

lateral rectus muscle

CN VII

Cell bodies (M, S, P)

Function

Innervation

Facial

M: facial nucleus

S: Nucleus Solitarius

P: superior salivatory nucleus

taste, facial movement, tension on bones of middle ear, salivation/lacrimation

anterior 2/3 tongue, muscles of facial expression; stapedius muscle, salivary and lacrimal glands

What do CN VII lesions cause?

Bell’s Palsy

Ramsay Hunt Syndrome

CN VIII

cell bodies

function

innervation

Vestibulocochlear

vestibular and cochlear nuclei

vestibular sensation and hearing

vestibular apparatus, cochlea

What does CN VIII lesions cause?

Acoustic Neuroma

CN IX

Cell bodies (S, M, P)

Function

Innervation

Glossopharyngeal

S: trigeminal sensory nucleus, nucleus solitarius

M: Nucleus Ambiguus

P: Inferior Salivatory Nucleus

Pharyngeal, tongue and middle ear sensation, taste, chemoreception, baroreception, swallowing, salivation, gag reflex

Pharynx, posterior third of tongue, middle ear, carotid body and sinus, stylopharyngeus muscle, parotid salivary gland

CN X

Cell bodies (S, M, P)

Function

Innervation

Vagus

S: trigeminal sensory nucleus, Nucleus Solitarius

M: Nucleus Ambiguus

P: Dorsal motor nucleus of vagus

Cardiac muscle function, respiratory and GI tract, speech, swallowing, general sensation, visceral sensation, chemoreception, baroreception

CN XI

Cell body

Function

Innervation

Spinal Accessory

Spinal Cord

Head and shoulder movement

Sternomastoid and trapezius muscles

CN XII

Cell body

Function

Innervation

Hypoglossal

Hypoglossal Nucleus

Tongue movement, chewing, sucking, and swallowing reflexes

Intrinsic and extrinsic tongue muscles

What do CN IX-XII lesions cause?

Pseudobulbar Palsy

Bulbar Palsy

Jugular Foramen Syndrome