doc. MUDr. Adriana Boleková, PhD. MVDr. Natália Hvizdošová, PhD. CENTRAL NERVOUS SYSTEM – is composed from spinal cord and brain

SPINAL CORD cranial border: foramen magnum, pyramidal decussation, exit of first pair of spinal nerves caudal border: level of L1 – L2 vertebrae medullary cone – filum terminale (S2) – cauda equina enlargements:  cervical enlargement (C5 – Th1): origin of nerves for upper extremity – brachial plexus  lumbosacral enlargement (L1 – S2): origin of nerves for lower extremity – lumbosacral plexus external features:  anterior median fissure  anterolateral sulcus – anterior roots of spinal nn.  posterolateral sulcus – posterior roots of spinal nn.  posterior median sulcus  posterior intermediate sulcus internal features: White matter  anterior funiculus (between anterior median fissure and anterolateral sulcus)  lateral funiculus (between anterolateral and posterolateral sulci)  posterior funiculus (between posterolateral sulcus and posterior median sulcus)  fasciculus gracilis  fasciculus cuneatus

Gray matter  anterior (ventral) horn – motor function: Rexed laminae I – VI  lateral horn – serves to visceral function: Rexed lamina VII  dorsal (posterior) horn – sensory information: Rexed laminae VIII – IX  central grey matter – interneurons: around central canal Rexed lamina X

Central canal  cranially opens into IV. ventricle  caudally expands into terminal ventricle vessels of spinal cord: Arteries: spinal brr. from surrounding arteries – anterior radicular aa., posterior radicular aa.: posterior spinal aa. (in posterolateral sulci) – for posterior 1/3 of spinal cord, white mater anterior spinal a. (in anterior median fissure) – for anterior 2/3 of spinal cord, grey mater

Veins: internal vertebral venous plexuses opens to external vertebral venous plexuses coverings and spaces of spinal cord: endorhachis – periosteum of vertebral canal epidural space: fatty tissue, internal vertebral venous plexuses  dura mater  arachnoid mater subarachnoid space: cerebrospinal fluid  pia mater BRAIN

Rhombencephalon (hindbrain)  Myelencephalon (Medulla oblongata)  Metencephalon (Pons + Cerebellum) Mesencephalon (midbrain) Prosencephalon (forebrain)  Diencephalon  Telencephalon

Brainstem (Truncus encephali)  Medulla oblongata (bulb of spinal cord)  Pons  Mesencephalon

BRAIN STEM

Medulla oblongata  from pyramidal decussation (crossing of anterior corticospinal tracts)  to bulbopontine sulcus (transverse groove between medulla oblongata and pons) longitudinal division: – ventrally:  anterior median fissure  foramen cecum  pyramid: contains fibers of anterior corticospinal tract  anterolateral sulcus: exit of hypoglossal n. (CN XII)  olive  posterolateral sulcus: exit of glossopharyngeal n. (CN IX), vagus n. (CN X), accessory n. (CN XI)  inferior cerebellar peduncles: connect medulla oblongata and pons – dorsally:  posterior median sulcus  fasciculus gracilis – gracile tubercle  intermediate sulcus  fasciculus cuneatus – cuneate tubercle  lower part of rhomboid fossa

Pons – cranial continuation of medulla oblongata structures: – ventrally:  bulbopontine sulcus: abducent n. (CN V.)  basilar sulcus: groove on ventral surface of pons, basilar a. runs within basilar sulcus  middle cerebellar peduncles: connect cerebellum to pons  pontocerebellar angle (pontocerebellar trigone): exits of facial n. (CN VII) and vestibulocochlear n. (CN VIII)  trigeminofacial line: forms lateral border of pons, between exits of trigeminal n. (CN V) and facial n. (CN VII),border between pons and cerebellum – dorsally  upper part of rhomboid fossa Rhomboid fossa  posterior surface of medulla oblongata and pons, forms floor of fourth ventricle structures:  median sulcus of rhomboid fossa: connects central canal to cerebral aqueduct  median eminence: laterally to median sulcus of rhomboid fossa  sulcus limitans: laterally to median eminence, border between alar and basal plates from developmental period

 superior part – superior fovea, locus ceruleus, facial colliculus (fibers of facial n. loop around ncl. of abducent n.)  intermediate part – medullary striae of rhomboid fossa vestibular area and acoustic tubercle (laterally to sulcus limitans)  inferior part – hypoglossal trigone: lies close to median sulcus (ncl. of hypoglossal n.) vagal trigone: laterally to hypoglossal trigone (ncl. of vagus n.) area postrema: caudally to vagal trigone inferior fovea: on top of vagal trigone

Mesencephalon  through all mesencephalon runs cerebral aqueduct (connects IIIrd and IVth ventricles)  superior cerebellar peduncles: connect mesencephalon and cerebellum parts:  cerebral peduncle: ventral to cerebral aqueduct – cerebral crus (basis pedunculi): interpeduncular fossa, posterior perforating substance, exit of oculomotor n. (CN III) – tegmentum: substantia nigra, red nucleus  tectum: dorsal to cerebral aqueduct – superior colliculi – brachium of superior colliculi (part of visual pathway) – inferior colliculi – brachium of inferior colliculi (part of auditory pathway) – exit of trochlear n. (CN IV)

CEREBELLUM

 vermis: middle unpaired part  hemisphere  anterior lobe  posterior lobe  flocculonodular lobe external features: folia of cerebellum fissures of cerebellum:  primary fissure: between anterior lobe and posterior lobe  posterolateral fissure: between posterior lobe and flocculonodular lobe internal features:  cerebellar cortex: gray matter  tree of life (arbor vitae): white matter cerebellar nuclei: gray matter  fastigial nuclei  emboliform nucleus  globose nuclei  dentate nucleus superior cerebellar peduncles: connect cerebellum to midbrain middle cerebellar peduncles: connect cerebellum to pons inferior cerebellar peduncles: connect cerebellum to medulla oblongata anatomical division of cerebellum: vermis hemisphere  lingula – vinculum lingulae  central lobule – ala of central lobule  culmen – quadrangular lobule primary fissure  declive – lobulus simplex  folium – superior semilunar lobule horizontal fissure  tuber – inferior semilunar lobule  pyramis – biventral lobule  uvula – tonsil posterolateral fissure  nodulus – flocculus

DIENCEPHALON  located upward and in front of midbrain  hypothalamic sulcus: border between sensory and motor parts of diencephalon

Hypothalamus  primary centre of ANS, located below hypothalamic sulcus structures:  mammillary body  tuber cinereum  infundibulum – hypophysis  optic chiasma – optic tract

Thalamus – sensory  above hypothalamic sulcus, the largest portion of diencephalon  'gate to consciousness', receives all sensory information (except olfactory) structures: Medial surface – interthalamic adhesion (intermediate mass)  medullary stria of thalamus – tenia thalami Dorsal surface  terminal sulcus – superior thalamostriate v., terminal stria  tenia choroidea – choroid plexus of lateral ventricle  lamina affixa  anterior tubercle  pulvinar Metathalamus: medial geniculate body – subcortical auditory centre lateral geniculate body – subcortical visual centre

Epithalamus  dorsomedially to thalamus, connected with limbic system structures:  habenula – habenular trigone  habenular commissure – epiphysis (pineal body)  posterior commissure TELENCEPHALON  cerebral hemispheres:  cerebral cortex – gray matter  medullary body – white matter  basal ganglia – gray matter  rhinencephalon and limbic systems Surfaces: superolateral, medial, and inferior surfaces Margins: superior, medial, and inferior margins Lobes: frontal, parietal, occipital, temporal lobes, and insula Poles: frontal, occipital, and temporal poles

Cerebral cortex – gyri and sulci Superolateral surface  lateral sulcus – anterior, ascending, and posterior rami  central sulcus Frontal lobe  precentral gyrus precentral sulcus  superior frontal gyrus superior frontal sulcus  middle frontal gyrus inferior frontal sulcus  inferior frontal gyrus – orbital part anterior ramus of lateral sulcus – triangular part ascending ramus of lateral – opercular part posterior ramus of lateral sulcus Parietal lobe  postcentral gyrus postcentral sulcus  superior parietal lobule intraparietal sulcus  inferior parietal lobule – supramarginal gyrus: around end of posterior ramus of lateral sulcus – angular gyrus: around end of superior temporal sulcus Occipital lobe  occipital gyri transverse occipital sulcus  lunate sulcus  preoccipital notch Temporal lobe  superior temporal gyrus – transverse temporal gyri superior temporal sulcus  middle temporal gyrus inferior temporal sulcus  inferior temporal gyrus Insula  limen of insula circular sulcus  long gyrus – central sulcus of insula  short gyri Medial surface of telencephalon  medial frontal gyrus  paracentral lobule  precuneus parietooccipital sulcus  cuneus – calcarine sulcus

cingulate sulcus  cingulate gyrus – isthmus of cingulate gyrus sulcus of corpus callosum  corpus callosum – rostrum, genu, body, splenium  septum pellucidum – laminae and cave of septum pellucidum  fornix – column, body, and crus of fornix  paraterminal gyrus  subcallosal area

Inferior surface of telencephalon  straight gyrus olfactory sulcus  olfactory bulb – olfactory tract – medial and lateral olfactory striae olfactory trigone – anterior perforating substance  optic n. (CN II) – optic chiasma – optic tract  orbital gyri – orbital sulci

hippocampal sulcus  uncus of parahippocampal gyrus – parahippocampal gyrus – lingual gyrus collateral sulcus – rhinal sulcus  medial occipitotemporal gyrus occipitotemporal sulcus  lateral occipitotemporal gyrus

Functional cortical areas:  Brodmannꞌs cytoarchitectonic map (1907)  motor and sensory Homunculus  motor areas – in frontal lobe  sensory areas – in parietal, occipital, and temporal lobes cortical areas:  primary: exact function, somatotopic organisation  secondary: close to primary areas, less detail organisation, gnostic function  association (tertiary): close to secondary areas, analysis and synthesis of information individual consciousness and personality Dominance of hemisphere  left hemisphere – analytic thinking, logic, mathematic, languages, science – for right-handers and 1/2 of left-handers  right hemisphere – holistic thinking, intuition, creativity, music, art – for 1/2 of left-handers

Medullary body – white matter – myelinated nerve fibers, have origin or/and termination in cerebral cortex  semioval centre – in horizontal section between cortex and basal ganglia  corona radiata – below semioval centre, above of corpus callosum  internal capsule – between basal ganglia and thalamus  corpus callosum – radiation of corpus callosum, forceps major and forceps minor Basal ganglia – masses of gray mater, initiation and control of voluntary movements – inhibition of involuntary activity, revision of information from primary motor cortex  caudate ncl. – head, body, and tail of caudate ncl.  lentiform ncl. – globus pallidus lateral (external) and medial (internal) – putamen  claustrum  amygdaloid body (amygdala) striatum = caudate ncl. + putamen lentiform ncl. = putamen + globus pallidus corpus striatum = caudate ncl. + lentiform ncl.

Basal ganglia are separated by bundles of white matter:  internal capsule – between head of caudate ncl. (in front) + thalamus (behind) ↔ lentiform ncl. – V shaped in horizontal section: anterior limb, genu and posterior limb  external capsule – between putamen and claustrum  extreme capsule – between claustrum and cortex of insula

Olfactory system olfactory bulb – olfactory tract – medial and lateral olfactory striae olfactory trigone – anterior perforating substance Piriform lobe:  primary olfactory cortex – piriform area in uncus of parahippocampal gyrus in temporal lobe: prepiriform area + periamygdalar area  secondary olfactory cortex – enthorinal area in parahippocampal gyrus in temporal lobe – orbitofrontal cortex in frontal lobe

Limbic system – functional system of cortical and subcortical neurons Limbic lobe: septum – cingulate gyrus – parahippocampal gyrus – amygdala – border between cortical areas and subcortical nuclei (limbus) – emotions, behaviour, learning, memory – mind and consciousness ↔ instincts – connects with hypothalamus, expresses by ANS – not only parts of telencephalon, but also parts of diencephalon and mesencephalon telencephalon: – cortical areas: hippocampal formation, septum Limbic association cortex: orbitofrontal cortex, cingulate and parahippocampal gyri, entorhinal area – subcortical areas: amygdala, basal ganglia diencephalon: thalamus – anterior ncl., mediodorsal ncl. (associating ncl.) hypothalamus – mammillary body, ventromedial ncl. epithalamus – habenular ncll. (connect with olfactory system) mesencephalon: reticular formation

Papez circuit  hippocampus  fornix  mammillary body  anterior ncl. of thalamus  cingulate gyrus  hippocampus Hippocampal formation – learning, memory  hippocampus  dentate gyrus: medially to hippocampus  subiculum: under hippocampus, on upper part of parahippocampal gyrus

Septum verum (septum) – positive emotions, pleasure, releases serotonin (like drugs, sex) Septal area:  paraterminal gyrus  subcallosal area

Amygdala (amygdaloid body) – negative emotions: aggression, anger, anxiety, fear – unconscious memory from early childhood when hippocampus is still immature

VESSELS AND DURAL SINUSES

Arteries of brain Telencephalon is supplied by:  posterior cerebral a. – mostly inferior surface of hemisphere and pons  middle cerebral a. – mostly superolateral surface of hemisphere  anterior cerebral a. – mostly medial surface of hemisphere

Arterial circle of Willis (circulus arteriosus cerebri): cerebral aa. – cortex and central aa. – deep parts – provides multiple paths for blood to supply brain if any of arteries are constricted  anterior communicating a. (one): between two anterior cerebral aa.  posterior communicating a. (two): between posterior cerebral a. and internal carotid a. (or middle cerebral a.)

 vertebral a. – posterior inferior cerebellar a. basilar a.: from connection of two vertebral aa. – for brainstem and cerebellum  anterior inferior cerebellar a.  pontine and mesencephalic aa.  superior cerebellar a.  posterior cerebral a. – posterior communicating a.  internal carotid a.  anterior cerebral a. – anterior communicating a.  middle cerebral a.

Veins of brain – have no valves  superficial cerebral vv. – in subarachnoid space, drain cerebral cortex  superior and inferior cerebral vv. – superior and inferior anastomotic vv.  superficial and deep middle cerebral vv.  deep cerebral vv. – drain internal structures of brain  internal cerebral v. – in choroid tela of IIIrd ventricle – superior thalamostriate v. – anterior septal v. – superior choroidal v.  basal v. – drains brainstem, opens to great cerebral v.  great cerebral v. – below splenium of corpus callosum, from two internal cerebral vv. Dural sinuses  between two layers of dura matter Confluence of sinuses:  superior sagittal sinus  straight sinus  occipital sinus  transverse sinus Origin of internal jugular v. in jugular foramen from:  sigmoid sinus  superior and inferior petrosal sinus others:  inferior sagittal sinus  sphenoparietal sinus  cavernous sinus

BRAIN VENTRICLES  filled by cerebrospinal fluid made by choroid plexus (from arachnoid mater)

IVth ventricle – unpaired ventricle in rhombencephalon  floor: rhomboid fossa  roof: superior medullary velum (frenulum of superior medullary velum) cerebellum – fastigium (highest point in roof of IVth ventricle) inferior medullary velum: choroid tela and choroid plexus of IVth ventricle – median aperture of IVth ventricle (unpaired), obex  laterally: lateral recess of IVth ventricle – lateral aperture of IVth ventricle (paired)  upward: cerebral aqueduct  downward: central canal

Cerebral aqueduct: along midbrain, connects IVth and IIIrd ventricles

IIIrd ventricle – unpaired ventricle located in diencephalon and partially in telencephalon  is connected to lateral ventricles through interventricular foramens  roof: choroid tela and choroid plexus of IIIrd ventricle  in front: lamina terminalis, anterior commissure  floor: optic recess, optic chiasma, infundibular recess (infundibulum), tuber cinereum, mammillary body  behind: posterior commissure, pineal recess, habenular commissure, suprapineal recess  laterally: medial surface of thalamus (medullary stria, choroid tenia, interthalamic adhesion, hypothalamic sulcus, interventricular foramen, column of fornix) Recesses of IIIrd ventricle:  optic recess – in front of optic chiasma  infundibular recess – above stalk of hypophysis  suprapineal recess – above pineal body  pineal recess – into pineal body

Lateral ventricle – paired, in both hemispheres, in all four lobes of telencephalon – communicate with the IIIrd ventricle through interventricular foramen  Anterior (frontal) horn: septum pellucidum, head of caudate ncl., rostrum and genu of corpus callosum  Central part (in parietal lobe): body of caudate ncl., lamina affixa of thalamus, body of fornix, body of corpus callosum  Posterior (occipital) horn: bulb of posterior horn, calcar avis, collateral trigone  Inferior (temporal) horn: collateral eminence, collateral trigone, choroid glomus – in bottom of inferior horn lies hippocampus – pes hippocampi, hippocampal digitations, fimbria of hippocampus – fimbria of fornix, dentate gyrus

COVERINGS OF BRAIN

Dura mater  tough fibrous membrane, toughly adherent to skull  forms duplicatures into skull cavity:  falx cerebri – between two cerebral hemispheres  falx cerebelli – between two cerebellar hemispheres  tentorium cerebelli – between cerebellum and occipital lobe  sellar diaphragm – covers sella turcica, has opening only for stalk of hypophysis

Arachnoid mater – soft translucent membrane, has no vessels and no nerves – arachnoid granulations – protrude to dural sinuses for absorption of cerebrospinal fluid subarachnoid space – between arachnoid and pia maters, filled by cerebrospinal fluid and vessels subarachnoid cisterns – extension of subarachnoid space, filled by cerebrospinal fluid the biggest is: cerebellomedullary cistern (cisterna magna) others: cistern of lateral fossa, interpeduncular cistern, pontine cistern, chiasmatic cistern, quadrigeminal cistern, pericallosal cistern, cisterna ambiens

Pia mater – thin, highly vascular membrane closely adherent to brain surface – follows brain surface, gyri and sulci  choroid plexus

NERVE PATHWAYS

– white mater, myelinated nerve fibers:  Association tracts: connect various areas in same hemisphere, ypsilaterally long intracortical fibers: inferior and superior longitudinal fascicles, cingulum, frontooccipital fasciculus, uncinate and arcuate fasciculi short subcortical fibers: between two neighbouring gyri, U-fibers  Commissural tracts: connect same areas between two hemispheres, contralaterally corpus callosum, anterior commissure, posterior commissure, habenular commissure, commissure of fornix  Projection tracts: connect areas of various levels of CNS, cortical areas ↔ subcortical areas Ascending fibers = sensory = afferent = corticopetal = directed to upper centers Descending fibers = motor = efferent = corticofugal = directed to lower centers – direct sensory pathways, indirect sensory pathways – direct motor pathways, indirect motor pathways

PROJECTION TRACTS Ascending tracts  General sensory tracts: from skin and movement system 1st neuron is inside of sensory ganglion of spinal or cranial nerve  Special sensory tracts: from specialised sensory organs Direct sensory pathways: conscious information A. General sensation: system of 3 neurons, 2nd neuron crosses, termination in sensory cerebral cortex  superficial sensation = exteroception from skin: – epicritic (fine) sensation: fine touch, discriminative sensation, vibration, recognition – protophatic (crude) sensation: touch and pressure, pain and temperature  deep sensation – proprioception from joints, tendons, and muscles movement sense

a) Sensory pathways from neck, trunk and limbs – general sensation:  Dorsal column pathway = main sensory pathway = spino-bulbo-thalamo-cortical tract – epicritic and proprioceptive sensation  Anterior spinothalamic tract – protophatic sensation: touch and pressure Lateral spinothalamic tract – protophatic sensation: urgent pain and temperature

 Spinoreticular tract – slow and diffuse pain  Spinotectal tract (has only 2 neurons) – spinovisual reflexes

b) Sensory pathways from head:  Trigeminothalamic tract – orofacial epicritic and protophatic sensation – orofacial proprioception

B. Special sensation  Visual pathway and collaterals from visual pathway: Pathway of pupillary contraction and accommodation Pathway of pupillary dilatation  Acoustic (auditory) pathway  Vestibular pathway  Gustatory (taste) pathway  Olfactory pathway

Indirect sensory pathways – unconscious information, system of 2 neurons, termination in cerebellum – coordination of movement, posture, and balance  Posterior and anterior spinocerebellar tracts: information from lower half of body  Cuneocerebellar tract: information from upper half of body

Descending tracts

Direct motor pathways: conscious motor activity of skeletal muscles Motor pathways to muscles of neck, trunk and limbs:  Corticospinal (pyramidal) pathway – the youngest pathway phylogenetically, upper motoneuron: in cerebral cortex, lower motoneuron: in anterior horn of spinal cord – Lateral corticospinal tract: 80% of fibers cross in pyramidal decussation, run in lateral funiculus of spinal cord to muscles of limbs – Anterior corticospinal tract: 20% of fibers cross in anterior commissure of spinal cord run in anterior funiculus of spinal cord to muscles of trunk Motor pathways to muscles of head and neck:  Corticonuclear tract – conscious movements of head and neck, facial expression, chewing, speech, upper motoneuron: cerebral cortex; lower motoneuron: nuclei of cranial nerves

Indirect motor pathways (extrapyramidal) – old pathways phylogenetically, unconscious motor activity, more upper motoneurons: ncl. ruber, black substance, reticular formation, vestibular ncll., tectum; lower motoneuron: motor nuclei in anterior horn of spinal cord and of cranial nerves  basal ganglia – modifying system, information from sensory cerebral cortex – modulates unconscious motor activity from cerebral cortex, involuntary reflexes  cerebellum – controlling system, coordinate postural, supporting, and locomotor mechanism