Ivana Pavlinac Dodig, M.D., Ph.D.

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We propose that Michelangelo, a deeply religious man and an accomplished anatomist, intended to enhance the meaning of this iconographically critical panel and possibly document his anatomic accomplishments by concealing this sophisticated neuroanatomic rendering within the image of God.

Suk I, Tamargo RJ. Concealed neuroanatomy in Michelangelo's Separation of Light From Darkness in the Sistine Chapel. Neurosurgery. 2010;66:851‐61.

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Iz Suk I, Tamargo RJ. Concealed neuroanatomy in Michelangelo's Separation of Light From Darkness in the Sistine Chapel. Neurosurgery. 2010;66:851-61.

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Cerebral cortexWhite matterBasal gangliaLimbic systemLateral cerebral ventricles

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Contains 15 bilion neuronsArea of 220 cm2

Histological arangement – functional units calledcortical columnsSulcii and gyrii

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Projection fibers (efferent or afferent: thalamocortical system and extrathalamic afferent fibers)Association fibers (axons of pyramidal neurons – II and III cortical layer)Commissural fibers (axons of pyramidal neurons – II and III cortical layer: corpus callosum, commissura anterior and commissura hippocampi)

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Regulation of motor functions!

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Nucleus caudatusPutamenGlobus pallidus(Claustrum) 

Substantia nigraSubthalamic nucleus

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Neostriatum

anatomical and functional relationships with neostriatum and globus pallidus

Neurological structure Basal nuclei

Corpus striatum Caudate nucleus + lentiformnucleus

Amygdala Amygdaloid nucleus

Claustrum Claustrum

Neostriatum Caudate nucleus + putamen

Paleostriatum Globus pallidus

Caudate nucleus Caudate nucleus

Lentiform nucleus Globus pallidus + putamen

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C‐shapedFollows the lateral ventricle for its entire lenghtHeadBodyTail 

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Between globus pallidus and external capsuleLateral to the internal capsule

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Major site of inputsinto the basal gangliafrom cerebral cortex, thalamus, substantianigra

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Lateral to the internal capsuleMadial to the putamenLateral and medial segment (separated bymedial medullary lamina)Primary region for the outflow of theinformation from the basalganglia (ansa and fasciculuslenticularis)

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Ansa lenticularis – frommedial segment of GP, ventromedial direction and caudallytoward midbrainFasciculus lenticularis – from pallidum, dorsomedial direction, around the dorsalsurface of nucl. subth. and curve around thedorsal aspect of zona incerta, dorsolateraldirection caudally toward midbrain

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Rostral to the red nucl. reverse course, rostraldirection = H field of Forel (pre‐rubral field)

Joined by dentatothalamic fibers = fasciculusthalamicus (H1 field of Forel)

Terminate in ventrolateral and ventralanterior thalamic nucl.

H2 field of Forel = fasciculus lenticularis

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Limbic systemHippocapmal formationSeptal areaBed nucleus of the stria terminalisNucleus accumbensSubstantia innominataAmygdala

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LOBUS LIMBICUS described by Paul Broca in 1878

Hippocampal formationSeptal areaAmygdalaAdjoining regions of cortex (entorhinal, pyriform)

Prefrontal cortexCingulate gyrus

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Anatomical and functional relationshipswith processes in limbic system

Lobus limbicusgyrus fornicatusformatio hippocampi

RhinencephalonMediobasal telencephalon 

(paleocortex)

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Gyrus fornicatus:Area subcallosaGyrus cinguliIsthmus gyri cinguliGyrus parahippocampalis

Paralimbic cortical areas

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Deep within the temporal lobeMedial wall of inferior horn of the lateral ventricle

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Central regulation of: emotional behaviourmotivational processesmemory functionshormonal and autonomicregulation

Dorsomedial direction until corpus callosum,then rostral until anterior commissure,  

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1. then ventrally into diencephalon(ant. thalamic nucl. and mammillary bodies) = postcommissural fornix

2. Then rostrally to septal area = precommissural fornix

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Hippocampus praecommissuralis = gyrus paraterminalisHippocampus supracommissuralisHippocampus retrocommissuralis:

Cornu ammonis (=hippocampus proper)Fascia dentata (=gyrus dentatus)Subiculum

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Relay nucl. of the hippocamp. to hypothalamus(functional extension of the HF)Primary receiving area (precommissural fornix)Projects to hypothalamus

oDorsal region – septum pellucidumoVentral region – large in humans

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Ventrolateral to the fornix at the level of anterior commissureRecieves fibers from amygdala, sents fibers to hypothalamus and autonomic centres of the brainstemRegulates autonomic, endocrine, and affective processes associated with amygdala

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Between septalarea, SI, putamen, caudatus

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Inputs from brainstem (DA), amygdala, hippocampal formation

Projects to substantia innominata, SN, VTA

Integrates the sequencing of motor responses associated with affectiveprocesses (and addictive – hedonicsystem).

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Between diagonal band of Broca, preoptic region, prepyriform area, striatumReciprocal connections with the amygdala, projects to lateral hypothalamus (relay fromA to lat.hypoth.)

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Basal nucelus of Meynert• Projects to cortex and limbic structures• Etiology of Alzheimer’s disease (ACh)

Deep within temporal lobeLateral, medial, central and basal nucleusModulate processes associated with hypothalamusand midbrain PAG: rage and aggression, flight and other affective processes, feeding behaviour, endocrine adn hormonal activity, sexual behavior, autonomic control

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Major pathway: stria terminalis1. frommedial amygdala, 2. dorsally around post.thalamus, 3. then follow the tail of caudate nucleus rostrally

(located ventromedially) 4. at the level of ant.commissure, descend

ventromedially through bed nucleus 5. end in the medial hypothalamus

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Stria terminalismajor output from amygdala

Internal capsuleAnterior commissureTrisynaptic loopPapez circuit

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Descending: corticospinal, corticopontine, corticobulbar pathwaysAscending: thalamocortical fibersSensorimotor functions!

Genu (corticobulbar)Anterior limb (frontopontine)Posterior limb (corticospinal)Separates thalamus fromGP, and caudate nucl. from putamen

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Rostral to the descending column of the fornixOlfactory fibers from anterior olfactory bulbFibers that originate in temporal lobe (amygdala)

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Connecting hippocampus with cerebralcortex1. fasciculus perforans2. mossy cell fibers3. Schaffer collaterals

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First order neuron: pyramidal neurons in entorhinal cortex (layer II and III)their axons form tractus perforansprojects to dentate gyrus ‐ granule cellfibers of fascia dentata (FD)

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Second order neuron: granule cells of fascia dentatatheir axons formMossy fiberspass through the hilus of FDsynapses on pyramidal neurons in CA3

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Third order neuron: pyramidal neurons of CA3their axons form Schaffer collateralssynapse in pyramidal neurons of CA1axons of CA1 neurons project to subiculum

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EC perforant path mossy fibers

Neuron I Neuron II Neuron III

Schaffercollaterals

subiculum

FD CA3

CA1

connects various structures of the telencephalonoriginates and ends in hippocampusaverage size of the circuit is 350 millimeters. 

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Hippocampal formation (subiculum) → fornix→mammillary bodies→mammillothalamic tract→ anteriorthalamic nucleus → cingulum→entorhinal cortex→ hippocampal

formation (FD).

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Contain CSF secreted primarily from choroid plexus (specializedepithelial cells)Source of electrolytes, protective and supportivemediumConduit for neuroactive and metabolic productsRemoves neuronal metabolic products from brain

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Anterior horn (in frontal lobe)Posterior horn (extends into occipital lobe)Inferior horn (in temporal lobe)Body (between interventricular foramen and posteriorhorn)

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