Corticospinal tract

(CST)

start cerebral cortex -->internal capsule -->crus cerebri -->brain stem to decussate at cervicomedullary junction-->spinal cord--> VH

volitional control of fine motor behavior

lesion:  @ brain stem--> C/L flaccidity-->spaz

Pontine Nucleus

(PonNu)

get corticopontine fibers from neocortex

axons form PCeF -->C/L MCP

cortico-ponto-cerebellar pathway

lesion:Unilateral lesion-->C/L limb ataxia

if lesion damage  CST--> C/L hemiparalysis masks ataxia

Central Tegmental Tract

(CTT)

links rostral brain stem w/ medulla.

lesion:palatal myoclonus

Lateral Lemniscus

(LL)

ascending pathway in the auditory system

lesion:Unilateral lesion--> B/L decreased hearing; greater in C/L ear

Lesions pons -->auditory hallucinations

PONTINE RETICULAR FORMATION

(PRetF)

control of autonomic functions and motor activity

&

ascending reticular activating system.--> regulate neural activity in thalamus/cerebral cortex; influences sleep-wake cycle.

lesion: disturb REM; lg. lesion-->death

VENTRAL TRIGEMINOTHALAMIC TRACT

(VTTr)

ascending fibers from C/L SpTNu

terminates in the ventroposterior medial nucleus

facial crude touch, pain, and thermal sense.

lesion:loss of crude touch, pain, and thermal sensation from C/L face

Lateral medullary lesion--> I/L SpTNu C/L ALS--> alternating analgesia

MEDIAL LEMNISCUS

(ML)

contain lg.myelinated axons from DCT X-ing as internal arcuate fibers

SCT fibers from nucleus Z join them

2PV, vibratory, proprioception

lesion: C/L loss 2PV, position, and vibratory sense

(ventral LE,  dorsal UE)

MEDIAL LONGITUDINAL FASCICULUS

(MLF)

interconnect vestibular nuclei w/oculomotor, trochlear, abducens nuclei as well as motoneurons controlling the cervical musculature.

lesion:. above the level of the abducens nucleus -->internuclear ophthalmoplegia

SUPERIOR CEREBELLAR PEDUNCLES

(SCP)

cerebellum output pathway

arises in the dentate nucleus

lesion:ataxia and clumsiness in extremeties. caudal to decussation--> I/L 

rostral to decussation --> C/L

anterolateral system

(ALS)

pain, crude touch, and temperature

lesion:C/L analgesia level down

pain/parasthesias @ level

CHIEF SENSORY NUCLEUS OF THE TRIGEMINAL NERVE

(CSNu)

receives Ab (group II), primaryafferent fibers from mechanoreceptors in I/L face.

analogous fxn to DCS

Axons cross midline--> join VTTr , end C/L thalamus

nociceptive info

lesion:loss of discriminatory touch, vib sense, 2PV,  stereognosis I/L face

TRIGEMINAL MOTOR NUCLEUS

(TriMoNu)

receives primary afferent fibers from I/L mesencephalic trigeminal nucleus and B/L input from the cerebral cortex (corticonuclear fibers).

axons leave pons in the CNV--> innervate I/L muscles of mastication.

lesion:paralysis I/L muscles of mastication.

B/L supranuclear lesions corticonuclear fibers--> jaw paresis w/ hyperactive jaw-jerk reflex

RUBROSPINAL TRACT

(RuSp)

controlling flexor muscle tone in proximal UE

lesion:Combo w/ CST -->severe weakness and spastic paralysis

RAPHE COMPLEX

(RaNu)

produce serotonin

mediating opiate-dependent control over nociception

lesion:pharmaceutical suppression RaNu and Trigeminal decrease threshold of pain

monosynaptic reflex arc controlling the force exerted by the jaw during chewing.

lesion:diminished jaw-jerk reflex I/L

VENTRAL SPINOCEREBELLAR TRACT

(VSCT)

TECTOSPINAL TRACT

(TecSp)

axons from neurons C/L superior colliculus--> x-ing midline--> cervical spinal cord.

mediating head/neck reflexes to unexpected stimuli.

CORTICONUCLEAR FIBERS

(CoNF)

LATERAL GENICULATE NUCLEUS

(LGNU)

thalamic relay for the visual system--> OPTIC RADIATIONS

superior portion of the retina is in superomedial part of geniculate;

inferior portion of the retina is in inferolateral part of the nucleus

lesion:lateral geniculate, optic tract, or optic radiations --> C/L hemianopsia.

Complete destruction  nucleus -->dense hemianopsia w/o macular sparing

anterior choroidal artery occlusion--> sparing narrow horizontal strip

DORSAL LONGITUDINAL FASCICULUS

(DLF)

extends from hypothalamus medulla.

regulating ANS

INFERIOR COLLICULUS

(IC)

major relay centers for uditory pathways.

receives afferent from C/L cochlear nucleus and B/L projections from  superior olivary and LLNu

reflex responses to unexpected stimuli

lesion: diminish C/L hearing

RADIATION OF THE TROCHLEAR NERVE

(TroNr)

innervatesC/L superior oblique muscle

lesion: globe to deflect downward/inward

CEREBRAL PEDUNCLE OR CRUS CEREBRI

(CC)

includes CoPF, CST

from the cerebral cortex and pass thru internal capsule.

lesion:Vascular--> w/ peduncles--> C/L limb paresis b/c loss CST fibers.

C/L facial paralysis in low quad loss  supranuclear innervation of cranial motor nuclei ,

C/L dystaxia from loss  corticopontine fibers

SUPERIOR COLLICULUS

(SC)

receive input from  visual, auditory, and somatic sensory systems, projections from frontal and parietal cortex.

forms a map  body and

external space. 

Map guides head, eye, and upper limb movements in tracking and responding to unexpected stimuli

parallel processing of visual information

lesion:increased saccade latencies and a defect in saccade execution (hypometria),  fall short of the target.

DECUSSATION OF THE SUPERIOR CEREBELLAR PEDUNCLE

(dSCP)

place where dentate nucleus and ventrolateral thalamic nucleus axons cross the midline

lesion: coma

BRACHIUM OF THE INFERIOR COLLICULUS

(BrIC)

axons from IC to I/L medial geniculate

major auditory projection from midbrain to thalamus.

lesion:C/L diminution of hearing 

MEDIAL GENICULATE NUCLEUS

(MGNu)

ascending auditory pathways (IC)--> MGNu--> I/L cerebral cortex.

fiber capsule is composed of ascending afferent fibers from BrIC and efferent fibers forming the auditory radiations to temporal (auditory) cortex.

lesion: diminished hearing

INTERPEDUNCULAR NUCLEUS

(IPNu)

relay station b/w limbic forebrain & brain stem serotonergic systems

afferent fibers from  septal area of  forebrain thru habenulointerpeduncular tract 

Efferent fibers connect w/ raphe nuclei and central gray

SUBSTANTIA NIGRA

(SN)

dorsomedial surface of CP.

receive striatonigral tract.

dopamine production

 control of the motor system.

lesions:paralysis from loss CST mask signs.

degenerative-->hypokinesia and bradykinesia--> Parkinson's

OCULOMOTOR NUCLEUS

(OcNu)

innervate four of the extraocular eye muscles & levator palpebrae muscle, ciliary ganglion

receives projections from  vestibular nuclei, abducens nucleus, prepositus hypoglossal nucleus, PPRF

lesion:

Ipsilateral eye positioned down and out

Pupil fixed and dilated, unresponsive to light

VENTRAL TEGMENTAL AREA

(VTA)

dopaminergic cells-->limbic forebrain structures

lesion:depleted in Parkinson's disease--> personality changes

PULVINAR NUCLEUS

largest thalamic nuclei

has representations of C/L visual hemispheres-->part of extrageniculate visual system

providing cortical attention for language-related tasks on dominant side and for mechanicospatial tasks on nondominant side

lesion: Sm hemorrhagic nondominant side -->disturb topographic memory, constructional apraxia, visual neglect

dominant side-->thalamic aphasia

DENTOTHALAMIC TRACT OR CEREBELLOTHALAMIC TRACTS

(CThT)

fibers b/w SCP decussation and the thalamus

lesion: C/L limb tremor, hypokinesia, and ataxia

Putamen

(Put)

receive glutaminergic fibers from I/L neocortex. 

end on cholinergic/ GABAergic neurons.

W/ caudate nucleus -->dorsal striatum.

part of basal ganglia.

regulate movementsof distal limb and influence various types of learning.

innervate I/L GP and  reticular portion of  substantia nigra.

lesion:chorea , athetosis ,dystonia,behavioral and cognitive changes

restricted to  putamen--> motor dysfunction C/L limbs

OPTIC RADIATIONS

(OpRad)

Meyer's loop.

fibers from superior visual fields pass into the temporal lobe

fibers from inferior visual fields pass deep to the parietal lobe

lesion: partial--> C/L quadrantanopsia

complete--> C/L hemianopsia

LATEROPOSTERIOR NUCLEUS

(LP)

receives afferent fibers from visual cortex/ SC-->multiple representations of the visual hemisphere.

effernt to posterior parietal cortex

involved in visuomotor activity.

lesion:disturb topographic memory and  constructional apraxia

Caudate Nucleus

(Cau)

receive glutaminergic fibers from I/L neocortex. 

end on cholinergic/ GABAergic neurons.

GABAergic fibers-->innervate I/L globus pallidus and  reticular portion of substantia nigra.

control behavioral and cognitive functions

lesion:chorea, athetosis, dystonia, behavioral and cognitive changes

EXTERNAL MEDULLARY LAMINA

(EML)

lat. thalamic border

separate thalamic nuclei from  reticular thalamic nucleus

composed ofthalamocortical /corticothalamic fibers passing in and out of internal capsule.

BODY OF THE FORNIX

(Fx)

major efferent pathway of hippocampus.

from dorsal surface of hippocampus-->paases over caudal thalamus->descend thru rostral thalamus--> hypothalamus/septal area.

lesion:interrupt hippocampal-hypothalamic connections-->amnesia

HABENULAR NUCLEUS

(Hab)

receives afferent from  septal nuclei via stria medullaris,projects to interpeduncular nuclei over the habenulointerpeduncular tract.

relay station in flow of limbic system infofrom the septal area to brain stem/spinal cord

HABENULOPEDUNCULAR TRACT

(HPTr)

Hab pass over this

AKA fasciculus retroflexus

pathway that olfactory info from forebrain can gain access to brainstem nuclei

Hypothalamus

(HyTh)

regulating endocrine/ANS

projections to autonomic nuclei of brain stem/spinal cord and connections to pituitary via the median eminence and infundibulum--> control over visceral/emotional behavior.

INTERNAL MEDULLARY LAMINA

(IML)

divides ventral nuclear grps from medial nuclear grps

contains ALS fibers and mesencephalic reticular formation endings

transmission of pain and maintenance of arousal state in cerebral cortex.

lesion:Sleep dysfunctions and altered levels of consciousness

Internal Capsule

(IntCap)

separates the caudate nucleus and the thalamus from the lenticular nucleus

Areas:

• Posterior limb--> corticospinal fibers-->sensory fibers

• Genu-->corticobulbar fibers b/w cortex and the brainstem.

• Anterior limb-->
  
  • 1) frontopontine (corticofugal) fibers from frontal cortex to pons;
  • 2) thalamocortico fibers connect the medial and anterior nuclei of the thalamus to the frontal lobes 
  • retrolenticular -->optic system fibers from lateral geniculate nucleus --> becomes optic radiation
  • Some fibers from medial geniculate nucleus (auditory)pass here.
  • lesion: C/L hemiparesis or hemiplegia

STRIA MEDULLARIS

(StMed)

from septal nuclei to habenular nuclei

part of the pathway for limbic system information moving from the septal area to the brain stem and spinal cord

Stria Terminalis

(StTer)

major output pathway of amygdala

articipates in anxiety and stress responses.

MIDBRAIN RETICULAR FORMATION

(MRetF)

preoculomotor system--> w/paramedian pontine reticular formation control vertical/horizontal eye movements

ascending reticular activating system--> modulate level of neural activity in cerebral cortex

lesion:to the ascending reticular activating system-->COMA

U/L lesion-->C/L "neglect syndrome"

to preoculomotor system-->loss of horizontal gaze

if damage descending corticospinal and corticonuclear fibers B/L--> "locked-in" syndrome

THALAMIC RETICULAR NUCLEUS

(ThRetNu)

around the main body of the thalamus.

b/w external medullary lamina and the internal capsule

modulating the output of individual thalamic nuclei. directing attention to novel stimuli, inhibiting attention to repetitive stimuli

Amygdaloid nucleus

(AmyNu)

LENTICULAR FASCICULUS

(LenFas)

Fibers from GP  pass thru internal capsule to enter  thalamus as LenFas. Once in the thalamus, joins w/ cerebellothalamic fibers --> thalamic fasciculus

lesion:sudden, unexpected, chorealike, or dystonic movements C/L limbs

comes from loss inhibition pallidothalamic fibers have on  ventrolateral nucleus

SUBTHALAMIC NUCLEUS

(SThNu)

receives fibers from I/L GPe, projects to GPi

"indirect output pathway" for basal ganglia

modulate GPi activity

SThNu/basal ganglia -->role in controlling the thalamocortical circuitrycerebral cortex output

lesion:loss of excitationto GPi--> can't repress ventral lateral/anterior anterior nuclei--> increase output  to premotor cerebral cortex--> increase motor output from neocortex--> violent, uncontrollable, ballistic movements in C/L proximal extremities

THALAMIC FASCICULUS

(ThFas)

made of cerebellothalamic fibers and lenticular fasciculus;

lesion:cerebellar ataxia/dysmetria C/L extremities b/c damage to cerebellothalamic fibers,

 sudden, unexpected, chorealike or dystonic movements of C/L limbs b/c loss pallidothalamic fibers

Anterior Commissure

(ACom)

ANSA LENTICULARIS

(AnLen)

passes out GP--> joins thalamic fasciculus--> ends ventrolateral nucleus and the ventroanterior nucleus  

inhibit thalamic neurons.