Cranial Nerves Flashcards
(59 cards)
GSA
GeneralSomaticAfferent
Somatosensory
Sensationfromskin,external ear, oralandnasalcavities
CarriedbyCNV, VII,IX,X
GSE
GeneralSomaticEfferent Somatomotor To skeletalmuscleofeye,tongue;SCMandtrapzeius mm.
CarriedbyCNIII,IV,VI,XI,XII
GVA
GeneralVisceralAfferent
Viscerosensory
Sensationfrompharynx;stretchreceptorsofthegut,
baroreceptorsofthecarotidandaorticbodies,
chemoreceptorsofgutandcarotidbody
Carried byCNVII,IX,X
GVE
General VisceralEfferent
Visceromotor
CN onlycarryparasympathetic innervationtosmoothand
cardiacmm.,salivaryandlacrimalglands,mucusglands
CarriedbyCNIII,VII,IX,X
SSA
SpecialSomatic Afferent
Vision,hearing,balance(CNII,VIII)
SVA
SpecialVisceral Afferent
Smell andTaste(CNI,VII,IX,X)
SVE
SpecialVisceralEfferent
Branchiomotor
Toskeletalmusclederivedfromthebranchialarches;
e.g.:mmofmastication,facialexpression,pharynx
(swallowing),larynx(speech)
CarriedbyCNV,VII,IX,X
Spinal nerves from forebrain
CNI‐II
Spinal nerves from midbrain
CNIII‐IV
Spinal nerves from pons
CNV‐VIII
Spinal nerves from medulla
CNIX‐XII
Spinal nerves from upper cervical spinal cord
CNXI
sensory and motor nuclei in midbrain
Sensory- trigeminalmesencephalic
(GSA; CNV)
Motor- occulomotor (GSE;CNIII)
Edinger‐Westphal (GVE; CNIII)
trochlear (GSE;CNIV)
sensory and motor nuclei in pons
Sensory- principal trigeminal (GSA;CN V,VII,IX,X), trigeminalspinal (GSA/GVA; CNV,VII,IX,X), vestibulocochlear (SSA;CN VIII)
Motor- abducens (GSE;CN VI), trigeminalmotor(SVE;CNV), facial (SVE;CNVII), superiorsalivatory (GVE;CNVII), inferiorsalivatory (GVE; CNIX)
sensory and motor nuclei in medulla
Sensory- trigeminalspinal
(GSA/GVA; CNV,VII,IX,X),
solitary (GVA/SVA;CNVII,IX,X),
vestibulocochlear (SSA;CNVIII)
Motor- ambiguus (SVE;CNIX,X),
dorsalmotor(SVE;CNX),
hypoglossal (GSE;CNXII)
sensory and motor nuclei in upper cervical spinal cord
Sensory- trigeminalspinal
(GSA/GVA; CNV,VII,IX,X)
Motor- spinalaccessory(GSE;CNXI)
TrigeminalMesencephalicNucleus
Containscellbodiesforproprioceptive
neuronscarriedbyCNV. From the midbrain
• Mechanoreceptors in the periodontalligaments ofteeth
• Golgitendonorgans,musclespindlesinthe
musclesofmastication
• Function:managejawopeningandclosing
reflexesduringchewing;preventdamageto
teethandotheroralstructures(tongue,cheeks,
etc.)duringchewing
Jawclosingreflex
UsedtotestCNVintegrity
• Tappingonthechinforcesthemandible
downwardsandstretchesthemasseter
• Reflexshouldbeabrisk,symmetricalclosingof
thejaws
TrigeminalPrincipalNucleus
Locatedinthepons • Synapsebetween1° and2° neurons carryingthesensationsoffinetouch and vibration • Nucleuscontainthecellbodiesof the2° neurons. • Theseaxonswillprojecttothe thalamusinthetrigeminothalamic tracts.
TrigeminalSpinalNucleus
• Locatedinthepons,medulla,and
uppercervicalspinalcord(approx.C1‐
C3levels).
• CNV enters the brainstem at pons; fibers will descend tothe spinalnucleus asthe trigeminal spinaltract.
• Parsoralis iscontinuous superiorlywith
thetrigeminalprincipalnucleus.
• Parscaudalis iscontinuousinferiorly
withthedorsalhornnucleiofthe
spinalcord.
• Synapsebetween1° and2° neurons
• Parsoralis mediatessensationsoffine
touchandvibration
• Parsinterpolaris andcaudalis mediate
sensationsofpain,deep touchand
temperature
• Nucleuscontain thecellbodies ofthe2° neurons.
• Theseaxonswillprojecttothe
contralateralthalamusinthe
trigeminothalamic tracts.
Nucleussolitarius
(medulla)
• GVA afferents from middle ear, pharynx, respiratory &GI tracts
• CN VIIfromnasopharynx,softpalate
• CNIX frommiddle ear, oropharynx
• CNX fromlarynx, thoracic andabdominal viscera
• SVAafferentsfortaste
• CN VII from oral (anterior2/3) tongue
• CNIX from pharyngeal (posterior1/3) tongueandvallate papillae
• CNX from epiglottis and rootof tongue
FacialMotorNucleus
Upper(dorsal)partofthefacialmotornucleus
• LMNsprojecttotheuppermotorbranchesofCNVII
(e.g.temporalbr.)
•Innervatesthemusclesoffacialexpressionoftheupperface(e.g.frontalisandorbicularisoculimm.)
Lower(ventral)partofthefacialmotornucleus
•LMNsprojecttothelowermotorbranchesofCNVII
(e.g.buccalandmandibularbr.)
•Innervatesthemusclesoffacialexpressionofthelowerface(e.g.zygomaticusmm.risorius m.,orbicularisoris m.)and the stapedius*
ReticularFormation
The“core”ofthebrainstem
• Intrinsic (transverse) projections connect sensory and motor
nuclei inthe brainstem, creating polysynaptic reflexes
• Intrinsicprojectionsare
bilateral,sothatreflexesare
bilateral(e.g.cornealblink
reflex– botheyesblink)
Glabellar reflex
instruct the patient to try not to blink. Tap lightly on the forehead
between the eyebrows. The first few taps should elicit blinks, then the blinking
should stop as the frontal lobe overrides the efferent limb. If blinking does not
stop, this is known as Myerson’s sign, and is an indication of frontal lobe
dysfunction (called frontal release) that may occur with diseases such as
Parkinson’s.
Afferent: CN V
Efferent: CN VII