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