Anatomy Demolab 2: Medulla oblongata, pons, cerebellum, fossa rhomboidea, ventriculus quartus
Pons: Internal features
2 parts distinguished on the cross section: - pars basilaris pontis - ventral - tegmentum pontis - dorsal - between - corpus trapezoideum Substantia grisea: multiple nuclei Substantia alba: - Tractus ascendentes - Tractus descendentes
Medulla oblongata: ventral surface
5 grooves: fissura mediana anterior, sulcus anterolateralis dex et sin, sulcus posterolateralis dex et sin Cranial nerves emerge: IX - n. glossopharyngeus, X - n. vagus, XI - n. accessorius, XII - n. hypoglossus - from sulcus anterolateralis
Substantia alba: Fibrae spinothalamicae
Conscious pain temperature and tactile pathway, Tractus spinothalamicus anterior + Tractus spinothalamicus lateralis, goes together with lemniscus medialis - from tractus bulbothalamicus
Substantia alba: Fasciculus gracilis et cuneatus
Conscious proprioception, partly tactile sensation, nucleus gracilis et cuneatus -> fibrae arcuatae internae -> decussatio lemnisci medialis -> thalamus
Substantia alba: Tractus afferentes
Conscious sensory pathways: - Fasciculus gracilis - Fasciculus cuneatus - Fibrae spinothalamicae Unconscious sensory pathways: - Tractus spinocerebellaris anterior - Tractus spinocerebellaris posterior - Tractus olivocerebellaris - Tractus vestibulocerebellaris
Cerebellum: External Description
Location: fossa cranii posterior and above pons and medulla oblongata, consists: - 2 hemisphere - hemispherium cerebelli - connecting part - vermis cerebelli - 3 pair of prominent fibre bundles - peduncles:pedunculi cerebellares superiores et medii et inferiores
Fossa rhomboidea: XI - n. accessorius
M. Nucleus ambiguus ( common with IX and XI nerves) - Laterally from trigonum n. hypoglossi M. Nucleus spinalis n. accessorii - In the spinal cord segments C1-C6
Fossa rhomboidea: IX - n. glossopharyngeus
M. Nucleus ambiguus ( common with X and XI nerves) - Laterally from trigonum nervi hypoglossi S. Nucleus tractus solitarii ( common with XIII and X nerves) - below striae medullares P. Nucleus salivatorius inferior - below striae medullares
Fossa rhomboidea: V - n. trigeminus
M. Nucleus motorius n. trigemini - in locus caeruleus S. Nucleus sensorius n. trigemini - tactile sense - laterally from nucleus motorius S. Nucleus mesencephalicus n. trigemini - Proprioception - goes upwards till mesencephalon S. Nucleus spinalis n. trigemini - Pain and temperature - Goes downwards till spinal cord upper segments Processes information also from VII, IX and X nerves
Fossa rhomboidea: VI - n. abducens
M. Nucleus n. abducentis - in colliculus facialis
Fossa rhomboidea: X - n. vagus
M. nucleus ambiguus ( common with IX and XI nerves) - laterally from trigonum nervi hypoglossi S. nucleus tractus solitarii ( common with XIII and IX nerves) - below striae medullares P. Nucleus dorsalis n. vagi - in trigonum n. vagi
Fossa rhomboidea: VII - n. facialis
M. nucleus n. facialis - laterally and deeper from colliculus facialis
Fossa rhomboidea: XII - n. hypoglossus
M. nucleus n. hypoglossi - in trigonum n. hypoglossi
Pons: Substantia grisea
Pars basilaris pontis: - nuclei pontis - part of the movement coordination pathway Tegmentum pontis: - V to VIII cranial nerve nuclei - Nuclei corporis trapezoidei: between corpus trapezoideum fibres and part of the auditory pathway - Formatio reticularis: nuclei reticulares and nuclei raphes
Fossa rhomboidea: VIII - n. vestibulocochlearis
Pars vestibularis: - S. Nuclei vestibulares ( 4 nuclei): Area vestibularis and medulla oblongata Pars cochlearis: - S. Nuclei cochleares ( dorsalis et ventralis): Area vestibularis, pons
Medulla Oblongata: Internal Features
Substantia grisea: embedded as separate nuclei in white matter, substantia alba: tractus ascendentes and tractus descendentes
Pons: Ventral Surface
Sulcus basilaris - in the midline - lies a. basilaris Sulcus pontobasilaris - between pons and medulla oblongata Pedunculi cerebellares medii - laterally Cranial nerves emerge: - V - n. trigeminus - on the border with pedunculi cerebellares medii - VI - n. abducens - in the groove between pyramis and pons - VII - n. facialis - VIII - n. vestibulocochlearis
Ventriculus quartus: 5 openings
Upper corner to aqueductus cerebri to ventriculus tertius, lower corner to canalis centralis, lateral corners - recessus lateralis dex et sin to aperturae laterales to patium subarachnoideum and cisterna pontocerebellaris, midline of the lower part of the roof - apertura mediana spatium subarchoideum and cisterna cerebellomedullaris
Medulla oblongata: Dorsal surface
Upper part fossa rhomboidea base - Lateral sides are thickened - pedunculi cerebellares inferiores Lower part - 3 grooves: - Sulcus medianus posterior - Sulcus intermedius posterior dex. et sin. - Sulcus posterolateralis
Ventriculus quartus: Parts of the roof
Upper: - Velum medullare superius (2) - between pedunculi cerebellares superiores Lower: - Velum medullare inferius (8) - between pedunculi cerebellares inferiores - Tela choroidea - Plexus choroideus (7) - produces LCS
Substantia grisea
VIII to XII cranial nerve nuclei, V cranial nerve nucleus - nucleus spinalis n. trigemini, nucleus gracilis - tuberculum gracile, nucleus cuneatus - tuberculum cuneatum, nucleus olivaris - oliva: starts tractus olivospinalis, starts tractus olivocerebellaris, reflex and balance maintenance pathway, formatio reticularis - between pedunculi cerebellares inferiores: nuclei reticulares, nuclei raphes - closer to the midline, produce serotonin, respiratory and cardiovascular centers
Cerebellum: Substantia alba
Vermis - arbor vitae Pedunculi cerebellares - tracts
Substantia alba: Tractus efferentes
Voluntary motor pathways: - tractus pyramidalis: fibrae corticospinales and fibrae corticonucleares Unvoluntary motor pathways: - tractus rubrospinalis - tractus tectospinalis - fasciculus longitudinalis medialis - tractus vestibulospinalis - tractus olivospinalis - tractus reticulospinalis
fossa rhomboidea
base: pons et medulla oblongata dorsal surfaces, upper border: pedunculi cerebellares superiores, lower border: pedunculi cerebellares inferiores. vertical midline: sulcus medianus, horizontal midline: striae medullares ventriculi quarti, sulcus limitans: laterally from sulcus medianus, eminentia medialis: between sulcus medianus et limitans, colliculus facialis: above striae medullares, locus caeruleus: in the upper part near sulcus limitans, trigonum nervi hypoglossi: narrowed part of eminentia medialis below striae medullares, trigonum nervi vagi: laterally from trigonum nervi hypoglossi, area vestibularis: in the lateral corners
Substantia alba: tractus pyramidalis
common voluntary motor pathway, fibrae corticospinales - voluntary movements through spinal nerves - 80% of fibres crosses - decussatio pyramidum - tractus corticospinalis lateralis - 20% of the fibres do not cross - tractus corticospinalis anterior fibrae corticonucleares - voluntary movements through cranial nerves - crosses, forms synapses with the IX X XI and XII nerve motor nuclei
substantia alba: tractus pyramidalis
common voluntary motor pathway, fibrae corticospinales - voluntary movements through spinal nerves, fibrae corticonucleares - voluntary movements through cranial nerves (V, VI, VII)
Substantia alba: Lemniscus trigeminalis
conscious pain temp tactile and proprioception pathway, fibres from n. trigeminus sensory nuclei together with lemniscus mediallis and fibrae spinothalamicae, crosses in the pons
Pons: Substantia alba: Lemniscus medialis
conscious proprioception and partly tactile sensation, continues through mesencephalon to thalamus
Cerebellum: Functions
coordination of movements and balance, maintains muscle tone, regulates voluntary movements, works in connection with vestibular extrapyramidal pyramidal and proprioceptive systems, takes part in learning of motor tasks and processes memory of skilled motor activity
Cerebellum: Fissurae Cerebelli
covers the surface of the hemispheres and vermis - folia cerebelli - elevations between fissurae
Encephalon - the brain
develops from neural tube cranial end, 3 vesicles - prosencephalon, mesencephalon, rhombencephalon
Medulla oblongata: external description
direct continuation of spinal cord, location: fossa cranii posterior, shape: cone-shaped with cut apex and basis towards pons, downwards: foramen magnum medulla spinalis, upwards: pons and pedunculi cerebellares medii, ventral surface: lies on clivus, dorsal surface: forms fossa rhomboidea
Cerebellum: Hemispheria cerebelli
facies superior, facies inferior, margo anterior, margo posterior - goes fissura horizontalis cerebelli - separates facies superior from facies inferior
Fossa rhomboidea
in the depth of white matter V - XII cranial nerve nuclei are embedded, along the midline - motor nuclei, laterally - autonomic nuclei, the most lateral - sensory nuclei
Pons: External Description
location: fossa cranii posterior, downwards: medulla oblongata, upwards: pedunculi cerebri, ventral surface: lies on clivus and convex, dorsal surface: forms fossa rhomboidea
Pons: dorsal surface
lower part, fossa rhomboidea base, lateral sides - pedunculi cerebellares superiores
cerebellum: pedunculi cerebellares inferiores
medulla oblongata
Cerebellum: Pedunculi cerebellares superiores
mesencephalon
rhombencephalon(hindbrain)
metencephalon and myelencephalon
Cerebellum: substantia grisea
nuclei cerebelli, nucleus dentatus: - coordination of the movements of the limbs - conscious and unconscious movement coordination pathway nucleus emboliformis, nucleus globosus, nucleus fastigii: - body balance Mnemonic: Don't Eat Greasy Food ( dentatus, emboliformis, globosi, fastigii)
Fossa rhomboidea: XIII - n. intermedius
part of n. facialis P. Nucleus salivatorius superior - above striae medullares S. Nucleus tractus solitarii ( common with IX and X nerves) - below striae medullares
Substantia alba: corpus trapezoideum
part of the auditory pathway, nuclei cochleares -> nuclei corporis trapezoidei -> lemniscus lateralis
Substantia alba: Lemniscus lateralis
part of the auditory pathway, starts from nuclei corporis trapezoidei, goes till subcortical auditory centers: - colliculi inferiores - reflex auditory pathway - corpus geniculatum mediale - true auditory pathway
Substantia alba: tractus corticopontocerebellaris
part of the movement coordination pathway, fibrae corticopontinae: - cortex cerebri - nuclei pontis fibrae pontocerebellares: - nuclei pontis - crosses - pedunculi cerebellares medii - cortex cerebelli
myelencephalon
parts of brain: medulla oblongata ventricles of brain: ventriculus quartus
metencephalon
parts of brain: pons, cerebellum, isthmus, and rhombencephali ventricles of brain: ventriculus quartus
diencephalon
parts of brain: thalamencephalon and hypothalamus ventricles of brain: ventriculus tertius
Mesencephalon ( midbrain)
parts of the brain: Lamina tecti, pedunculi cerebri ventricles of the brain: aqueductus cerebri s. sylvii
telencephalon
parts of the brain: hemispheria cerebri and rhinencephalon ventricles of brain: ventriculus lateralis et sinister
Pons: Substantia Alba: Tractus afferentes
passes through tegmentum pontis, conscious sensory pathways: - lemniscus medialis - lemniscus trigeminalis - fibrae spinothalamicae Unconscious sensory pathways: - tractus spinocerebellaris anterior - corpus trapezoideum - lemniscus lateralis
Cerebellum: Pedunculi cerebellares medii
pons
cerebellum: internal features
substantia grisea: - outer layer - cortex cerebelli - embedded within white matter - nuclei cerebelli substantia alba: - in vermis - plain layer with multiple branching - arbor vitae - in hemispheres - thicker layer
Prosencephalon ( forebrain)
telencephalon and diencephalon
Ventriculus quartus
tent-shaped, base: fossa rhomboidea, roof: tegmen ventriculi quarti - fastigium ventriculi quarti
Substantia alba: pedunculi cerebellares medii
tractus pontocerebellaris: - part of the movement coordination pathway. starts from nuclei pontis
Substantia alba: pedunculi cerebellares superiores
tractus spinocerebellaris anterior: - unconscious proprioception pathway tractus cerebellorubralis: - part of the common conscious and unconscious movement and balance coordination pathway - nucleus dentatus - pedunculi - nucleus ruber mesencephali
Substantia alba: Pedunculi cerebellares inferiores
tractus spinocerebellaris posterior: - unconscious proprioception pathway tractus olivocerebellaris: - sense of balance from nucleus olivarius tractus vestibulocerebellaris: - unconscious balance pathway from VIII cranial nerve nucleus vestibularis
Substantia alba: tractus vestibulocerebellaris
unconscious balance regulation through VIII nerve nuclei, nuclei vestibulares, pedunculi cerebellares inferiores, cortex cerebelli
Substantia alba: tractus olivocerebellaris
unconscious balance regulation, crosses, nucleus olivaris, pedunculi cerebellares inferiores, cortex cerebelli
Substantia alba: Tractus spinocerebellaris anterior
unconscious proprioception, continues through mesencephalon, pedunculi cerebellares superiores, cerebellum
Substantia alba: tractus spinocerebellaris posterior
unconscious proprioception, goes via pedunculi cerebellares inferiores, cerebellum
Substantia alba: tractus spinocerebellaris anterior
unconscious proprioception, passes further through pons and mesencephalon, pedunculi cerebellares superiores, cerebellum
Cerebellum: Vermis cerebelli
upper part - merges with facies superior, lower part - separated from the hemispheres by the grooves
Pons: Substantia alba: tractus efferentes
voluntary motor pathways: - tractus pyramidalis: fibrae corticospinales and fibrae corticonucleares - tractus corticopontocerebellaris Unvoluntary motor pathways: - tractus rubrospinalis - tractus tectospinalis - fasciculus longitudinalis medialis - tractus reticulospinalis