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MIDBRAIN
- MESENCEPHALON; MIDBRAIN
- upper and shortest part of brainstem
- EXTERNAL FEATURES OR SURFACES
- VENTRAL SURFACE
- emerges from cerebral hemispheres joins to form
- crus cerebri of midbrain
- converges downwards to enter
- pons
- forms posterolateral boundary of
- interpeduncular fossa
- superficial surface
- corrugated by underlying longitudinal fibers
- crosses transversely from above downwards by
- optic tract ,
- taenia pontis
- superior cerebellar artery , posterior cerebral artery
- medial side
- groove
- occulomotor nerve emerges
- dorsal aspect
- trochlear nerve emerges
- curls around lateral aspect of cerebral peduncles
- DORSAL SURFACE
- shows four rounded elevations called corpora quadrigemina
- separated from each other by
- cruciform sulcus
- vertical limb of sulcus when
- traced above forms a depression
- lodges pineal body
- traced below becomes continuous with
- frenulum veli
- median ridge on dorsal surface of superior medullary velum
- laterally from colliculi
- two superior
- superior colliculus
- two inferior
- inferior colliculus
- INTERNAL STRUCTURE
- Mid brain divided by coronal plane passing through cerebral aqueduct in to two parts
- anterior part or cerebral peduncle
- parts from dorsal to ventral
- tegmentum
- substantia nigra
- curved , crescent shaped
- pigmented band of grey matter
- deeply pigmented nerve cells
- contain melanin ( polymerized form of dopamine )
- synthesize dopamine
- carried through their axons ( nigrostriatal fibers)
- to corpus striatum
- iron
- spiky process project in to crus cerebri
- parts
- dorsal part (pars compacta ) - medium sized cells
- pars reticularis ( ventral part ) - few cells
- intermingled with fibres of crus cerebri
- crus cerebri
- most anterior part
- white matter
- descending tracts
- connect cerebral cortex to
- anterior horn cells of spinal cord
- cranial nuclei
- pontine nuclei
- middle 2/3 of crus
- corticospinal
- corticonuclear
- medial 1/6 th of crus
- frontopontine
- lateral 1/6 th of crus
- temporopontine , parietopontine , occipitopontine
- posterior part or tectum
- LEVELS OF SECTION
- Transverse section of midbrain at level of inferior colliculus
- grey matter
- white matter
- central part of tegmentum
- decussation of superior cerebellar peduncle
- ventral lateral part of tegmentum
- medial to lateral
- medial lemniscus
- trigeminal lemniscus
- spinal lemniscus
- lateral lemniscus
- median longitudinal fasciculus
- tectospinal tracts
- rubrospinal tracts
- transverse section of midbrain at level of superior colliculus
- grey matter
- more centrally
- occulomotor nucleus
- edinger westphal nucleus
- emerging fibres pass through
- medial side of crus cerebri in posterior of interpeduncular fossa
- mesencephalic nucleus of trigeminal nerve
- more peripheral
- nucleus of superior colliculus
- connections
- prectectal nucleus
-
- cigar shaped
- contains iron
- MESENCEPHALON; MIDBRAIN
- Interpeduncular fossa
- Posterior perforated substance
- Oculomotor sulcus
- Cerebral peduncle
- Cerebral crus
- Lateral groove
- Tegmentum of midbrain
- Trigone of lateral lemniscus
- Superior cerebellar peduncle
- Frenulum
- Tectal plate; quadrigeminal plate
- Brachium of inferior colliculus
- Brachium of superior colliculus
- Inferior colliculus
- Superior colliculus
- Cerebral peduncle
- Base of peduncle
- Cerebral crus
- Pyramidal tract
- Corticospinal fibres
- Corticonuclear fibres
- Corticopontine fibres
- Frontopontine fibres
- Occipitopontine fibres
- Parietopontine fibres
- Temporopontine fibres
- Corticoreticular fibres
- Substantia nigra
- Compact part
- Lateral part
- Reticular part
- Retrorubral part
- Tegmentum of midbrain
- White substance
- Central tegmental tract
- Rubro-olivary fibres
- Cerebello-olivary fibres
- Mesencephalic corticonuclear fibres
- Hypothalamospinal fibres
- Base of peduncle
- Tectopontine tract
- Lateral tectobulbar tract
- Medial lemniscus
- Trigeminal lemniscus
- Medial longitudinal fasciculus
- Mesencephalic tract of trigeminal nerve
- Posterior longitudinal fasciculus; dorsal longitudinal fasciculus Schütz
- Rubronuclear tract
- Rubrospinal tract Monakow
- Rubro-olivary tract
- Spinal lemniscus; anterolateral tracts; anterolateral systém
- Spinothalamic fibres
- Spinoreticular fibres
- Spinomesencephalic fibres
- Spinotectal fibres
- Spinoperiaqueductal fibres
- Spinohypothalamic fibres
- Superior cerebellar peduncle
- Decussation of superior cerebellar peduncles
- Tectobulbar tract
- Tectopontine tract
- Tectospinal tract
- Pretecto-olivary fibres
- Tecto-olivary fibres
- Tegmental decussations
- Posterior tegmental decussation; dorsal tegmental decussation Meynert
- Anterior tegmental decussation; ventral tegmental decussation Forel
- Corticomesencephalic fibres
- Grey substance
- Nucleus of oculomotor nerve
- Accessory nuclei of oculomotor nerve
- Visceral nuclei; autonomic nuclei
- Anterior medial nucleus; ventral medial nucleus
- Posterior nucleus; dorsal nucleus
- Interstitial nucleus Cajal
- Central precommissural nucleus
- Nucleus of posterior commissure Darkšewič
- Ventral subdivision
- Interstitial subdivision
- Dorsal subdivision
- Interpeduncular nucleus
- Accessory nuclei of optic tract
- Posterior nucleus; dorsal nucleus
- Lateral nucleus
- Medial nucleus
- Lateroposterior tegmental nucleus; laterodorsal tegmental nucleus
- Mesencephalic nucleus of trigeminal nerve
- Nucleus of trochlear nerve
- Parabigeminal nucleus
- Periaqueductal grey substance; central grey substance
- Peripeduncular nucleus
- Red nucleus
- Magnocellular part
- Parvocellular part
- Posteromedial part; dorsomedial part
- Reticular formation
- Sagulum nucleus
- Subbrachial nucleus
- Anterior tegmental nuclei; ventral tegmental nuclei
- Interfascicular nucleus
- Parabrachial pigmented nucleus
- Paranigral nucleus
- Cuneiform nucleus
- Subcuneiform nucleus
- Pedunculopontine tegmental nucleus
- Compact part; compact subnucleus
- Dissipated part; dissipated subnucleus
- Raphe nuclei
- Posterior raphe nucleus; dorsal raphe nucleus
- Inferior linear nucleus
- Intermediate linear nucleus
- Superior linear nucleus
- Aqueduct of midbrain; cerebral aqueduct Sylvii
- Opening of aqueduct of midbrain; opening of cerebral aqueduct
- Tectum of midbrain
- Tectal plate; quadrigeminal plate
- Inferior colliculus
- Nuclei of inferior colliculus
- Central nucleus
- External nucleus
- Pericentral nucleus
- Superior colliculus
- Brachium of inferior colliculus
- Brachium of superior colliculus
- Commissure of inferior colliculus
- Commissure of superior colliculus
- Decussation of trochlear nerve fibres
- Reticular nuclei
- Cuneiform nucleus
- Subcuneiform nucleus
- Pedunculopontine tegmental nucleus
- Compact part; compact subnucleus
- Dissipated part; dissipated subnucleus
- Parapeduncular nucleus
TERMINOLOGY
| 531 | MESENCEPHALON | MESENCEPHALON; MIDBRAIN | ||
| 532 | Fossa interpeduncularis | Interpeduncular fossa | ||
| 533 | Substantia perforata posterior | Posterior perforated substance | ||
| 534 | Sulcus nervi oculomotorii | Oculomotor sulcus | ||
| 535 | Pedunculus cerebri | Cerebral peduncle | ||
| 536 | Crus cerebri | Cerebral crus | ||
| 537 | Sulcus lateralis mesencephali | Lateral groove | ||
| 538 | Tegmentum mesencephali | Tegmentum of midbrain | ||
| 539 | Trigonum lemnisci lateralis | Trigone of lateral lemniscus | ||
| 540 | Pedunculus cerebellaris superior | Superior cerebellar peduncle | ||
| 541 | Frenulum veli medullaris superioris | Frenulum | ||
| 542 | Lamina tecti; lamina quadrigemina | Tectal plate; quadrigeminal plate | ||
| 543 | Brachium colliculi inferioris | Brachium of inferior colliculus | ||
| 544 | Brachium colliculi superioris | Brachium of superior colliculus | ||
| 545 | Colliculus inferior | Inferior colliculus | ||
| 546 | Colliculus superior | Superior colliculus | ||
| 547 | Pedunculus cerebri | Cerebral peduncle | ||
| 548 | Basis pedunculi | Base of peduncle | ||
| 549 | Crus cerebri | Cerebral crus | ||
| 550 | Tractus pyramidalis | Pyramidal tract | ||
| 551 | Fibrae corticospinales | Corticospinal fibres | ||
| 552 | Fibrae corticonucleares | Corticonuclear fibres | ||
| 553 | Tractus corticopontinus | Corticopontine fibres | ||
| 554 | Fibrae frontopontinae | Frontopontine fibres | ||
| 555 | Fibrae occipitopontinae | Occipitopontine fibres | ||
| 556 | Fibrae parietopontinae | Parietopontine fibres | ||
| 557 | Fibrae temporopontinae | Temporopontine fibres | ||
| 558 | Fibrae corticoreticulares | Corticoreticular fibres | ||
| 559 | Substantia nigra | Substantia nigra | ||
| 560 | Pars compacta | Compact part | ||
| 561 | Pars lateralis | Lateral part | ||
| 562 | Pars reticularis | Reticular part | ||
| 563 | Pars retrorubralis | Retrorubral part | ||
| 564 | Tegmentum mesencephali | Tegmentum of midbrain | ||
| 565 | Substantia alba | White substance | ||
| 566 | Tractus tegmentalis centralis | Central tegmental tract | ||
| 567 | Fibrae rubroolivares | Rubro-olivary fibres | ||
| 568 | Fibrae cerebelloolivares | Cerebello-olivary fibres | ||
| 569 | Fibrae corticonucleares mesencephali | Mesencephalic corticonuclear fibres | ||
| 570 | Fibrae hypothalamospinales | Hypothalamospinal fibres | ||
| 571 | Lemniscus lateralis | Base of peduncle | ||
| 572 | Tractus tectopontinus | Tectopontine tract | ||
| 573 | Tractus tectobulbaris lateralis | Lateral tectobulbar tract | ||
| 574 | Lemniscus medialis | Medial lemniscus | ||
| 575 | Lemniscus trigeminalis | Trigeminal lemniscus | ||
| 576 | Fasciculus longitudinalis medialis | Medial longitudinal fasciculus | ||
| 577 | Tractus mesencephalicus nervi trigemini | Mesencephalic tract of trigeminal nerve | ||
| 578 | Fasciculus longitudinalis posterior; fasciculus longitudinalis dorsalis Schütz | Posterior longitudinal fasciculus; dorsal longitudinal fasciculus Schütz | ||
| 579 | Tractus rubronuclearis | Rubronuclear tract | ||
| 580 | Tractus rubrospinalis Monakow | Rubrospinal tract Monakow | ||
| 581 | Tractus rubroolivaris | Rubro-olivary tract | ||
| 582 | Lemniscus spinalis; tractus anterolaterales | Spinal lemniscus; anterolateral tracts; anterolateral systém | ||
| 583 | Fibrae spinothalamicae | Spinothalamic fibres | ||
| 584 | Fibrae spinoreticulares | Spinoreticular fibres | ||
| 585 | Fibrae spinomesencephalicae | Spinomesencephalic fibres | ||
| 586 | Fibrae spinotectales | Spinotectal fibres | ||
| 587 | Fibae spinoperiaqueductales | Spinoperiaqueductal fibres | ||
| 588 | Fibrae spinohypothalamicae | Spinohypothalamic fibres | ||
| 589 | Pedunculus cerebellaris superior | Superior cerebellar peduncle | ||
| 590 | Decussatio pedunculorum cerebellarium superiorum | Decussation of superior cerebellar peduncles | ||
| 591 | Tractus tectobulbaris | Tectobulbar tract | ||
| 592 | Tractus tectopontinus | Tectopontine tract | ||
| 593 | Tractus tectospinalis | Tectospinal tract | ||
| 594 | Fibrae pretectoolivares | Pretecto-olivary fibres | ||
| 595 | Fibrae tectoolivares | Tecto-olivary fibres | ||
| 596 | Decussationes tegmentales | Tegmental decussations | ||
| 597 | Decussatio tegmentalis posterior Meynert | Posterior tegmental decussation; dorsal tegmental decussation Meynert | ||
| 598 | Decussatio tegmentalis anterior Forel | Anterior tegmental decussation; ventral tegmental decussation Forel | ||
| 599 | Fibrae corticomesencephalicae | Corticomesencephalic fibres | ||
| 600 | Substantia grisea | Grey substance | ||
| 601 | Nucleus nervi oculomotorii | Nucleus of oculomotor nerve | ||
| 602 | Nuclei accessorii nervi oculomotorii | Accessory nuclei of oculomotor nerve | ||
| 603 | Nuclei viscerales; nuclei autonomici | Visceral nuclei; autonomic nuclei | ||
| 604 | Nucleus anteromedialis | Anterior medial nucleus; ventral medial nucleus | ||
| 605 | Nucleus dorsalis | Posterior nucleus; dorsal nucleus | ||
| 606 | Nucleus interstitialis Cajal | Interstitial nucleus Cajal | ||
| 607 | Nucleus precommissuralis centralis | Central precommissural nucleus | ||
| 608 | Nucleus commissurae posterioris Darkšewič | Nucleus of posterior commissure Darkšewič | ||
| 609 | Pars ventralis | Ventral subdivision | ||
| 610 | Pars interstitialis | Interstitial subdivision | ||
| 611 | Pars dorsalis | Dorsal subdivision | ||
| 612 | Nucleus interpeduncularis | Interpeduncular nucleus | ||
| 613 | Nuclei accessorii tractus optici | Accessory nuclei of optic tract | ||
| 614 | Nucleus posterior | Posterior nucleus; dorsal nucleus | ||
| 615 | Nucleus lateralis | Lateral nucleus | ||
| 616 | Nucleus medialis | Medial nucleus | ||
| 617 | Nucleus tegmentalis posterolateralis | Lateroposterior tegmental nucleus; laterodorsal tegmental nucleus | ||
| 618 | Nucleus mesencephalicus nervi trigemini | Mesencephalic nucleus of trigeminal nerve | ||
| 619 | Nucleus nervi trochlearis | Nucleus of trochlear nerve | ||
| 620 | Nucleus parabigeminalis | Parabigeminal nucleus | ||
| 621 | Substantia grisea centralis | Periaqueductal grey substance; central grey substance | ||
| 622 | Nucleus peripeduncularis | Peripeduncular nucleus | ||
| 623 | Nucleus ruber | Red nucleus | ||
| 624 | Pars magnocellularis | Magnocellular part | ||
| 625 | Pars parvocellularis | Parvocellular part | ||
| 626 | Pars posteromedialis; pars dorsomedialis | Posteromedial part; dorsomedial part | ||
| 627 | Formatio reticularis | Reticular formation | ||
| 628 | Nucleus saguli; sagulum | Sagulum nucleus | ||
| 629 | Nucleus subbrachialis | Subbrachial nucleus | ||
| 630 | Nuclei tegmentales anteriores | Anterior tegmental nuclei; ventral tegmental nuclei | ||
| 631 | Nucleus interfascicularis | Interfascicular nucleus | ||
| 632 | Nucleus pigmentosus parabrachialis | Parabrachial pigmented nucleus | ||
| 633 | Nucleus paranigralis | Paranigral nucleus | ||
| 634 | Nucleus cuneiformis | Cuneiform nucleus | ||
| 635 | Nucleus subcuneiformis | Subcuneiform nucleus | ||
| 636 | Nucleus tegmentalis pedunculopontinus | Pedunculopontine tegmental nucleus | ||
| 637 | Pars compacta | Compact part; compact subnucleus | ||
| 638 | Pars dissipata | Dissipated part; dissipated subnucleus | ||
| 639 | Nuclei raphes | Raphe nuclei | ||
| 640 | Nucleus raphe posterior | Posterior raphe nucleus; dorsal raphe nucleus | ||
| 641 | Nucleus linearis inferior | Inferior linear nucleus | ||
| 642 | Nucleus linearis intermedius | Intermediate linear nucleus | ||
| 643 | Nucleus linearis superior | Superior linear nucleus | ||
| 644 | Aqueductus mesencephali; aqueductus cerebri Sylvii | Aqueduct of midbrain; cerebral aqueduct Sylvii | ||
| 645 | Apertura aqueductus mesencephali; apertura aqueductus cerebri | Opening of aqueduct of midbrain; opening of cerebral aqueduct | ||
| 646 | Tectum mesencephali | Tectum of midbrain | ||
| 647 | Lamina tecti; lamina quadrigemina | Tectal plate; quadrigeminal plate | ||
| 648 | Colliculus inferior | Inferior colliculus | ||
| 649 | Nuclei colliculi inferioris | Nuclei of inferior colliculus | ||
| 650 | Nucleus centralis | Central nucleus | ||
| 651 | Nucleus externus; nucleus lateralis | External nucleus | ||
| 652 | Nucleus pericentralis | Pericentral nucleus | ||
| 653 | Colliculus superior | Superior colliculus | ||
| 654 | Stratum zonale; lamina i | Zonal layer; layer i | ||
| 655 | Stratum griseum superficiale; lamina ii | Superficial grey layer; layer ii | ||
| 656 | Stratum opticum; lamina iii | Optic layer; layer iii | ||
| 657 | Stratum griseum intermedium; lamina iv | Intermediate grey layer; layer iv | ||
| 658 | Stratum medullare intermedium; lamina v | Intermediate white layer; layer v | ||
| 659 | Stratum griseum profundum; lamina vi | Deep grey layer; layer vi | ||
| 660 | Stratum medullare profundum; lamina vii | Deep white layer; layer vii | ||
| 661 | Brachium colliculi inferioris | Brachium of inferior colliculus | ||
| 662 | Brachium colliculi superioris | Brachium of superior colliculus | ||
| 663 | Commissura colliculi inferioris | Commissure of inferior colliculus | ||
| 664 | Commissura colliculi superioris | Commissure of superior colliculus | ||
| 665 | Decussatio fibrarum nervorum trochlearium | Decussation of trochlear nerve fibres | ||
| 666 | Nuclei reticulares | Reticular nuclei | ||
| 667 | Nucleus cuneiformis | Cuneiform nucleus | ||
| 668 | Nucleus subcuneiformis | Subcuneiform nucleus | ||
| 669 | Nucleus tegmentalis peduncolopontinus | Pedunculopontine tegmental nucleus | ||
| 670 | Pars compacta | Compact part; compact subnucleus | ||
| 671 | Pars dissipata | Dissipated part; dissipated subnucleus | ||
| 672 | Nucleus parapeduncularis | Parapeduncular nucleus |
Discussion