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Brainstem IIMedical NeuroscienceDr. Wiegand

Internal Brainstem

Cranial nerve nucleiLocation of selected tractsReticular formation

Developmental Organization

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Developmental Organization

SulcusLimitans

Developmental Organization

From Pritchard &Alloway: Fig. 4-1

From Pritchard &Alloway: Fig. 4-1

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Cranial Nerve Nuclei Organization

Medial to sulcus limitans

GSE ⇒ SVE ⇒GVE

Lateral from sulcus limitans

VA ⇒ GSA ⇒SSA

From Pritchard &Alloway: Fig. 4-4

From Pritchard &Alloway: Fig. 4-4

MOTSEN

Generalizations

Sensory nuclei lateral to sulcus limitansMotor nuclei medial to sulcus limitansVisceral nuclei are on either side of sulcusInnervation of skeletal muscle (GSE & SVE) most medialGeneral and special visceral afferent nuclei in same column

Cranial Nerves –Telencephalon & Diencephalon

Olfactory –smell (SVA)

Optic –vision (SSA)

I, II

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Cranial Nerves –Mesencephalon

Oculomotor –extraocular eye muscles (GSE) –oculomotor nucleusPSNS to eye (GVE) –Edinger-Westphalnucleus

Trochlear –extraocular muscle (sup. oblique) (GSE) –trochlear nucleus

III, IV

Cranial Nerves –Metencephalon

Trigeminal –Masticatory muscles (SVE) – trigeminal motor nucleus General sensation of the head and face (GSA) – trigeminal complex

Abducens –extraocular muscle (lat. rectus) (GSE) –abducens nucleus

V, VI

Cranial Nerves –Metencephalon

Facial –Facial expression muscles (SVE) – facial motor nucleusGlands (submandibular, sublingual & lacrimal) (GVE) – superior salivatory & lacrimal nucleusTaste (SVA) – rostral solitary nucleusGeneral sensation of ear (GSA) – trigeminal complex

VII

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Cranial Nerves –Metencephalon

Vestibulocochlear –Hearing (SSA) –dorsal and ventral cochlear nucleiBalance (SSA) –vestibular nuclei

VIII

Cranial Nerves –Mylencephalon

GlossopharyngealStylopharyngeus muscle (SVE) – n. ambiguusPSNS to parotid gland (GVE) – inferior salivatory n. Taste (SVA) – rostral solitary n.Carotid body sensation (GVA) – caudal solitary n.General sensation from ear & tongue (GSA) –trigeminal complex

IX

Cranial Nerves –Mylencephalon

VagusMuscles of larynx & pharynx (SVE) – n.ambiguusPSNS to thorax and upper abdomen (GVE) – dorsal motor n. of X (DMV)Sensory from viscera (GVA) – caudal solitary n.Taste (SVA) – rostralsolitary n.General sensation from ear (GSA) - trigeminal complex

IX

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Cranial Nerves –Mylencephalon

Accessory –innervates trapezius and sternocleidomastoid (SVE or GSE) – motor nucleus of XI in upper cervical cord

Hypoglossal –tongue muscles (GSE) –hypoglossal nucleus

XI, XII

Cranial Nerve Nuclei GroupsGSE & SVE – Motor Nuclei of:

III, IV, V, VI, VII, XI, XII ambiguus

GVE – Parasympathetic NucleiEdinger-Westphal nucleusLacrimal & salivatory (superior, inferior) nuclei Dorsal Motor Nucleus of X

SVA (Taste) – Rostral Solitary nucleusGVA – Caudal Solitary nucleusGSA – Trigeminal (TBNC)SSA – Cochlear and Vestibular nuclei

Tongue mm.NoneHypoglossalMotorhypoglossalXII

Trap & SCMnoneaccessory nucleusmotor accessoryXI

Mm of larynx/pharynxViscera

EpiglottisViscera sensory

External ear

nonemultiple

inf. (nodose) of Xinf. (nodose) of Xsup. (jugular) of X

n. ambiguousdorsal motor

rostral solitarycaudal solitary

trigeminal

motorPSNStaste

sensorysensory

vagusX

Mm of larynxParotid gland

TongueSoft palate & pharynx

External ear

noneotic

inf. (petrosal) of IXinf. (petrosal) of IX

n. abiguusinferior salivatory

rostral solitarycaudal solitary

trigeminal

motorPSNStaste

sensorysensory

glossopharyngealIX

Cochlea Vestibular app

spiralvestibular

cochlear (dorsal, ventral) & vestibularhearingbalance

vestibulocochlearVIII

Mm facial expressLacrimal gland

Submandibular/lingualTongue

External ear

nonesubmandibular and sphenopalatine

geniculate

facialsuperior salivatory

-rostral solitary

trigeminal

motorPSNStaste

sensory

facialVII

Lateral rectus mmnoneabducensMotorabducensVI

Mm of masticationSensory of face

nonetrigeminal

motor VSpV, PrV, mesV

MotorSensory

trigeminalV

Superior obliqueNoneTrochlearMotortrochlearIV

Extraocular mmConstr. Pup & ciliary

noneciliary

oculomotorEdinger-Westphal

MotorPSNS

oculomotorIII

Retinaretinalateral geniculate bodyvisionopticII

Nasal cavityolfactory bulb-smellolfactoryI

PeripheralTargetPeripheral GangliaNucleusFunctionNameNumber

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Learning Internal Anatomy

Recognize outline of brainstemMidbrain

• Inferior vs. superior colliculiPonsMedulla

• Open vs. closedPlace nuclei in correct levelRecognize orientation of sliceLearn Pathways

Relationship of tractsPlaces of decussation

http://lansing.bellarmine.edu/pt/atlas/cover.html

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Sensory NucleiSensory DecussationMedial LemniscusAnterolateral System

ASCENDING PATHWAYS

Spinocerebellar Tracts

Corticospinal &Corticobulbar Tracts(Pyramidal Tract)

DESCENDING PATHWAY

CRANIAL NERVES

Edinger-Westphal NucleiOculomotor NucleiTrigeminal NerveTrigeminal NucleiHypoglossal NucleusDorsal Motor of VagusSolitary Nucleus

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Red nucleusRed nucleus

SubstantiaNigra

SubstantiaNigra

Inferior olivarynucleus

Inferior olivarynucleus

Other Brainstem Nuclei

Reticular Formation

Diffuse, poorly differentiated brainstem nucleiOccupies tegmentum of brainstemModulates:

PainMuscle tone and reflexesAutonomic functions e.g. respiration, blood pressure, cardiac functionArousal, awareness and attention

Reticular Formation

Raphe

med

ial m

ediallate

ral lateral

Ascending Input

Ascending Input

Cerebellarprojecting

nuclei

Cerebellarprojecting

nuclei

Spinal Cord & Brainstem Nuclei

Forebrain & Brainstem Nuclei

Descending Input

Descending Input

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Midline Raphe Nuclei

Mostly serotoninergiccells – send and receive extensive ascending and descending projectionsRegulate pain, arousal and sleep

Parasagittalmedial nuclei

Motor regulationMedial (facilitates extensors) reticulospinaltractLateral (facilitates flexors) reticulospinal tractAlso autonomic regulation

ARAS exerts excitatory input to cortex for consciousness and attention

Regulates attentionInhibits pain at spinal cord levelRegulates autonomic function

Locus Ceruleus & Medial Reticular Zone

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ParasagittalLateral Nuclei

Receives input to mediate visceral and cranial nerve reflexesProjects to parasagittal medial nucleiPedunculopontine n.

Acetylcholine projecting cellsAscending projection to inferior frontal cortex/intralaminar n.Input from basal ganglia output nucleiProjects to brainstem motor nuclei (VST, RST)

PedunculopontineNucleus

Wallenberg’s Syndrome

Thrombosis of PICA

Lateral medullarysyndrome

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Wallenberg’s Syndrome

Structures involved:Inf. Cerebellar peduncle (ipsilateral ataxia)SpV tract & nucleus (ipsilateral loss pain & temperature)Anterolateral system (contralateral loss of body pain & temperature)N. ambiguus (dysphagia & dysphonia)Vestibular n. (nystagmus and postural instability)

Well…