Pons

substantia alba - tegmentum of pons

- tractus ascendentes - tractus descendentes

pons - surfaces

- ventral - dorsal

substantia grisea - tegmentum of pons

1. nuclei craniales nuclei of cranial nerves V-VIII in fossa rhomboidea 2. nuclei corporis trapezoidei part of auditory pathway 3. formatio reticularis

pathway for coordination of movements

1st neurons: - in frontal, parietal, occipital and temporal regions of cortex cerebri - axons form tractus corticopontinus + synapse with 2nd neurons 2nd neurons: nuclei pontis - axons form tractus pontocerebellaris - crossed - run to opposite side of cerebellum via pedunculi cerebellares medii

internal features of pons

horizontal section anteriorly: basilar part of pons posteriorly: tegmentum of pons inbetween: corpus trapezoideum (white matter) --> part of auditory pathway

pons - location

location: on clivus in cranium downwards: medulla oblongata upwards: pedunculi cerebri

substantia grisea - basilar part

nuclei pontis - 2nd neurons of pathway for voluntary coordination of movements between nuclei pontis fibrae pontis transversae - tract fibers synapse in nuclei pontis - tractus corticopontinus and tractus pontocerebellaris

Nerves in pons

on border: pons <--> pedunculus cerebellaris medius - V: nervus trigeminus (radix sensoria (thick) and radix motoria (thin)) sulcus bulbopontinus - VI: nervus abducens pyramis <--> pons - VII: nervus facialis + nervus intermedius (sometimes XIII cranial nerve) - VIII: nervus vestibulocochlearis n. facialis + n. vestibulocochlearis - laterally to VIth nerve - oliva <--> pedunculus cerebellaris medius

nuclei corporis trapezoidei

part of auditory pathway

pons - ventral surface

prominent convex from side to side midline: sulcus basilaris for a. basilaris laterally: pedunculus cerebellaris medius--> cerebellum sulcus bulbopontinus - medulla oblongata <--> pons - 4 cranial nerves (VI-VIII + nervus intermedius)

substantia alba - tegmentum of pons - lemniscus medialis

tractus ascendentes

substantia alba - tegmentum of pons - tractus ascendentes

tractus ascendentes 1. lemniscus medialis 2. lemniscus spinalis 3. lemniscus trigeminalis 4. tractus spinocerebellaris anterior 5. lemniscus lateralis and corpus trapezoideum

substantia alba - tegmentum of pons - lemniscus trigeminalis

tractus ascendentes formed by: axons of sensory nuclei of V cranial nerve (21) --> crossed

substantia alba - tegmentum of pons - lemniscus spinalis

tractus ascendentes formed by: fibres of tractus spinothalamicus anterior et laterlis

substantia alba - tegmentum of pons - lemniscus lateralis and corpus trapezoideum

tractus ascendentes part of auditory pathway lemniscus lateralis (10) (connects nuclei cochlearis + olivares with colliculi inferiores) corpus trapezoideum (1)

substantia alba - tegmentum of pons - tractus spinocerebellaris anterior

tractus ascendentes (17) formed by: axons of nucleus intermediomedialis ascends to: cerebellum - runs through pons + mesencephalon - via pedunculi cerebellares superiores function: unconscious proprioception /deep sensation pathway

substantia alba - tegmentum of pons - tractus reticulospinalis

tractus descendentes

substantia alba - tegmentum of pons - tractus descendentes

tractus descendentes 1. tractus tectospinalis 2. tractus rubrospinalis 3. tractus reticulospinalis 4. fasciculus longitudinalis medialis

substantia alba - pars basilaris

tractus descendentes 1. tractus corticospinalis 2. tractus corticonuclearis 3. tractus corticopontinus 4. tractus pontocerebellaris

pars basilaris - tractus corticopontinus

tractus descendentes formed by: axons of cells fo secondary motory cortex descend to: nucleus pontinus function: pathway for voluntary coordination of complex movements

pars basilaris - tractus pontocerebellaris

tractus descendentes formed by: axons of nucleus pontinus descend to: cerebellum - fibres cross function: pathway for voluntary coordination of complex movements

pars basilaris - tractus corticonuclearis

tractus descendentes formed by: axons of pyramidal cells in cortex - pyramidal system descends to: motor nuclei of cranial nerves (V - VII) --> synapse function: coordination of voluntary movements of head + neck

pars basilaris - tractus corticospinalis

tractus descendentes pyramidal system

substantia alba - tegmentum of pons - fasciculus longitudinalis medialis

tractus descendentes (12)

substantia alba - tegmentum of pons - tractus rubrospinalis

tractus descendentes (16)

substantia alba - tegmentum of pons - tractus tectospinalis

tractus descendentes (18)

pons - dorsal surface

upper part of fossa rhomboidea pedunculi cerebellares superiores - directed to midbrain velum medullare superius - white matter - between pedunculi cerebellares superiores

pons - substantia alba

white matter of basil part: - tractus descendentes white matter of tegmentum of pons: - tractus ascendentes - tractus descendentes