Comparative AnatomyComparative AnatomyNervous SystemNervous System
Kardong Kardong Chapter 16Chapter 16
Part 15 Part 15
Primary Brain VesiclesPrimary Brain Vesicles
Prosencephalon (Forebrain)Prosencephalon (Forebrain) Smell Smell
Mesoncephalon (Midbrain)Mesoncephalon (Midbrain) VisionVision
Rhombencephalon (Hindbrain)Rhombencephalon (Hindbrain) Hearing Hearing
Figure 15.1. Primary brain vesicles (book figure 16.25).
Figure 15.2. Basic brain plan.
Primary Brain Vesicles Primary Brain Vesicles (cont’d.)(cont’d.)
Figure 15.3. Brain divisions.
HindbrainHindbrain MyelencephalonMyelencephalon
Medulla oblongataMedulla oblongata Involuntary reflexes Involuntary reflexes
Vagal lobeVagal lobe Metencephalon Metencephalon
CerebellumCerebellum Roof of metencephalonRoof of metencephalon Reflex control ofReflex control of
skeletal muscleskeletal muscle Pons - Floor of Pons - Floor of
metencephalon - relay metencephalon - relay station of sensory and motor station of sensory and motor tracts between spinal cord tracts between spinal cord and cerebrumand cerebrum
Figure 15.4. Regional divisions of the brain (book figure 16.25).
HindbrainHindbrain (cont’d.)(cont’d.)
4th ventricle4th ventricle Cavity of hindbrainCavity of hindbrain
Posterior choroid plexusPosterior choroid plexus Roof in hindbrainRoof in hindbrain 44thth ventricle tissue ventricle tissue Cerebrospinal fluidCerebrospinal fluid
Tela choroideaTela choroidea Roof of medullaRoof of medulla Thin membraneThin membrane
Figure 15.5. Choroid plexus shown in a larval anuran.
Brain Divisions/VesiclesBrain Divisions/Vesicles
Figure 15.6. Regions of the vertebrate brain (Fig. 16.32)
MidbrainMidbrain No subdivisionsNo subdivisions
Roof – tectum; floor - tegmentumRoof – tectum; floor - tegmentum Optic lobesOptic lobes
Optic reflex centersOptic reflex centers Well developed in birdsWell developed in birds
Auditory lobesAuditory lobes Caudal to optic lobesCaudal to optic lobes
Superior (optic) and inferior Superior (optic) and inferior (auditory) colliculi- when lobes occur (auditory) colliculi- when lobes occur togethertogether Corpora quadrigemina Corpora quadrigemina
collectivelycollectivelyFigure 15.7. Mesencephalon and tectum region.
MidbrainMidbrain (cont’d.)(cont’d.)
33rdrd ventricle ventricle Cavity of midbrainCavity of midbrain
Cerebral aqueduct Cerebral aqueduct Restricted passagewaysRestricted passageways Conducts between Conducts between 33rdrd and 4 and 4thth ventricle ventricle Aqueduct of Sylvius when Aqueduct of Sylvius when
restricted furtherrestricted further
Figure 15.8. Cerebral aqueduct and ventricles of brain.
Forebrain - DiencephalonForebrain - Diencephalon
Optic chiasmaOptic chiasma Two optic nerves crossTwo optic nerves cross
Pituitary glandPituitary gland Caudal to optic chiasmaCaudal to optic chiasma
Saccus vasculosus Saccus vasculosus Posterior to pituitary in Posterior to pituitary in
some fishsome fish Depth receptorDepth receptor
Figure 15.9. Regions of the diencephalon of a shark with third ventricle in red.
Forebrain- Diencephalon Forebrain- Diencephalon (cont’d.)(cont’d.)
HypothalamusHypothalamus Floor of diencephalonFloor of diencephalon
ThalamusThalamus Walls of diencephalonWalls of diencephalon 33rdrd ventricle cavity ventricle cavity
Communicates with lateral Communicates with lateral ventriclesventricles
Foramen of MonroForamen of MonroFigure 15.10. Medial view of the brain showing thalamus and hypothalamus of the diencephalon.
Forebrain- Diencephalon Forebrain- Diencephalon (cont.’d)(cont.’d)
EpithalamusEpithalamus Several evaginationsSeveral evaginations Roof of diencephalonRoof of diencephalon Paraphysis anteriorlyParaphysis anteriorly Epiphyseal complexEpiphyseal complex
PinealPineal PhotoreceptorsPhotoreceptors
ParapinealParapineal Pineal eye (3Pineal eye (3rdrd eye) eye)
Figure 15.11. Epithalamus; gross mid-sagittal section of the human brain.
Figure 15.12. Pineal in detail (see book figure 16.37).
Forebrain- TelencephalonForebrain- Telencephalon
Cerebral hemispheres posteriorCerebral hemispheres posterior Rhinencephalon anterior Rhinencephalon anterior
OlfactionOlfaction Lower vertebratesLower vertebrates
Rhinencephalon prominentRhinencephalon prominent Hemisphere smallerHemisphere smaller
Higher vertebratesHigher vertebrates Hemispheres increase in sizeHemispheres increase in size Olfactory get smallerOlfactory get smaller
Figure 15.13. Frontal section of cerebral hemisphere formation.
Evolution of Vertebrate BrainEvolution of Vertebrate Brain
Figure 15.14. Phylogenetic enlargement of vertebrate brains (see Fig. 16.33).
Vertebrate Brains Vertebrate Brains (cont’d.)(cont’d.)
Figure 15.15. Dorsal view of vertebrate brains .
Fish CerebrumFish Cerebrum
Primitive sensoryPrimitive sensory Pallium- dorsal areaPallium- dorsal area
Motor areaMotor area Subpallium- ventral areaSubpallium- ventral area
Globus pallidus (striatum)Globus pallidus (striatum)
Figure 15.16. Embryonic development of the telencephalon (Book figure 16.42.
Amphibian CerebrumAmphibian Cerebrum Similar pallium and globus pallidus Similar pallium and globus pallidus Split left and right hemispheresSplit left and right hemispheres
Figure 15.17. Globus pallidus of amphibian; left cerebral hemisphere.
Reptile CerebrumReptile Cerebrum Cerebrum is huge compared to Cerebrum is huge compared to
amphibiansamphibians Increase of lateral wallsIncrease of lateral walls Pushes into lateral ventriclePushes into lateral ventricle
Dorsal ventricular ridge formsDorsal ventricular ridge forms Receives visual, auditory, and Receives visual, auditory, and
sensory stimulisensory stimuli
Figure 15.18. Globus pallidus of reptile and bird; left cerebral hemisphere.
Bird CerebrumBird Cerebrum Similar to reptilesSimilar to reptiles Avian ridge (hyperstriatum)Avian ridge (hyperstriatum)
Stratum of neurons that capped ridgeStratum of neurons that capped ridge Processes visual informationProcesses visual information Important to instinctive stereotypic Important to instinctive stereotypic
behaviorbehavior Migration and courtshipMigration and courtship
Figure 15.19. Globus pallidus of reptile and bird; left cerebral hemisphere.
Mammalian CerebrumMammalian Cerebrum
Lateral ventricles extremely expandedLateral ventricles extremely expanded NeocortexNeocortex
Higher mental facilitiesHigher mental facilities Grooves (sulci)Grooves (sulci) Folds (gyrae)Folds (gyrae)
Figure 15.20. Neocortex of mammalian brain.
Mammalian Cerebrum Mammalian Cerebrum (cont.’d)(cont.’d)
Figure 15.21. Ventral view of human brain (see book Fig 16.36).
Mammalian Cerebrum Mammalian Cerebrum (cont.’d)(cont.’d)
Portion of primitive brain retainedPortion of primitive brain retained Ventral mediallyVentral medially Hippocampus- ancient olfactory Hippocampus- ancient olfactory
palliumpallium Memory storage?Memory storage?
Globus pallidum pushed interiorlyGlobus pallidum pushed interiorly Basal gangliaBasal ganglia
Changes in basal ganglia Changes in basal ganglia motor motor dysfunctiondysfunction Parkinson’s DiseaseParkinson’s Disease
Figure 15.22. Globus pallidus of human; left cerebral hemisphere
Mammalian Cerebrum Mammalian Cerebrum (cont.’d)(cont.’d)
Figure 15.23. Sagittal section of the human brain (book Fig. 16.37).
Cranial NervesCranial Nerves Amniotes have 12Amniotes have 12 Anamniotes have 10Anamniotes have 10 Terminal nerve (Nerve 0)- uncommon in humansTerminal nerve (Nerve 0)- uncommon in humans
Associated with pheromone receptorsAssociated with pheromone receptors
Figure 15.24. Cranial nerve locations on the brain.
Figure 15.25. Cranial nerve innervation(book Fig. 16.15).
Figure 15.26. Cranial nerve innervation(book Fig. 16.15).
Cranial Nerves Cranial Nerves (cont.’d)(cont.’d)
Figure 15.27. Cranial nerves in 6th week embryo.
Figure 15.28. Head organization in 4th week embryo (book figure 16.39).
Cranial Nerves Cranial Nerves (cont.’d)(cont.’d)
Cranial Nerves Cranial Nerves (cont.’d)(cont.’d)
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