The document discusses the development of the primary brain vesicles and divisions in the brains of different vertebrates. It notes that the brain originally forms from three primary vesicles - the prosencephalon (forebrain), mesencephalon (midbrain) and rhombencephalon (hindbrain). As vertebrates evolve, the forebrain increases in size and complexity, developing structures like the cerebrum, cerebellum and basal ganglia. In mammals, the lateral ventricles expand greatly and the neocortex develops, enabling higher mental functions. Across species, changes in brain structures correlate with new sensory abilities and behaviors.

1. Comparative AnatomyComparative Anatomy
Nervous SystemNervous System
Note Set 12Note Set 12
Chapter 16Chapter 16

2. Primary Brain VesiclesPrimary Brain Vesicles
 Prosencephalon (Forebrain)Prosencephalon (Forebrain)
 SmellSmell
 Mesoncephalon (Midbrain)Mesoncephalon (Midbrain)
 VisionVision
 Rhombencephalon (Hindbrain)Rhombencephalon (Hindbrain)
 HearingHearing
Figure 15.1: Primary brain vessicles
(book figure 16.13).

3. Figure 15.2: Basic brain plan.
Primary Brain VesiclesPrimary Brain Vesicles (con’t)(con’t)
Figure 15.3: Brain divisions.

4. HindbrainHindbrain
 MyelencephalonMyelencephalon
 Medulla oblongataMedulla oblongata
 Involuntary reflexesInvoluntary reflexes
 Vagal lobeVagal lobe
 MetencephalonMetencephalon
 CerebellumCerebellum
 Roof of metencephalonRoof of metencephalon
 Reflex control of skel.Reflex control of skel.
musclemuscle
 PonsPons
Figure 15.4: Neural tube development.

5. HindbrainHindbrain (con’t)(con’t)
 Lateral ventriclesLateral ventricles
 Two cerebral hemispheresTwo cerebral hemispheres
 Posterior choroid plexusPosterior choroid plexus
 Roof in hindbrainRoof in hindbrain
 44thth
ventricle tissueventricle tissue
 Cerebral spinal fluidCerebral spinal fluid
 Tela choroideaTela choroidea
 Roof of medullaRoof of medulla
 Thin membraneThin membrane
Figure 15.5: Choroid plexus shown of
larval anuran (book figure 16.18).

6. Divisions and VesiclesDivisions and Vesicles
Figure 15.6: Divisions of the brain and ventricles numbered.

7. MidbrainMidbrain
 No subdivisionsNo subdivisions
 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 inferiorSuperior (optic) and inferior
(auditory) colliculi- when lobes(auditory) colliculi- when lobes
occur togetheroccur together
 Corpora quadrigeminaCorpora quadrigemina
collectivelycollectively
Figure 15.7: Mesoncephalon and
tectum region.

8. MidbrainMidbrain (con’t)(con’t)
 33rdrd
ventricleventricle
 Optic ventricles- extensionOptic ventricles- extension
to optic lobeto optic lobe
 Ventricles disappear inVentricles disappear in
higher phylogenyhigher phylogeny
 Cerebral aqueductCerebral aqueduct
 Restricted passagewaysRestricted passageways
 Conducts 3Conducts 3rdrd
and 4and 4thth
ventricleventricle
 Aqueduct of Sylvius whenAqueduct of Sylvius when
restricted furtherrestricted further Figure 15.8: Cerebral aqueduct and ventricles of
brain.

9. Forebrain- DiencephalonForebrain- Diencephalon
 Optic chiasmaOptic chiasma
 Two optic nerves crossTwo optic nerves cross
 Pituitary glandPituitary gland
 Caudal to optic chiasmaCaudal to optic chiasma
 Saccus vasculosusSaccus vasculosus
 Posterior to pituitary in somePosterior to pituitary in some
fishfish
 Depth receptorDepth receptor
Figure 15.9: Regions of the
diencephalon of a shark with third
ventricle in red (book figure 16.19).

10. Forebrain- DiencephalonForebrain- Diencephalon (con’t)(con’t)
 HypothalamusHypothalamus
 Floor of diencephalonFloor of diencephalon
 Autonomic nervous systemAutonomic nervous system
 ThalamusThalamus
 Walls of diencephalonWalls of diencephalon
 33rdrd
ventricle cavityventricle cavity
 Communicates with lateralCommunicates with lateral
ventriclesventricles
 Foramen of MonroForamen of Monro
Figure 15.10: Medial view of the brain
showing thalamus and hypothalamus of
the diencephalon.

11. Forebrain- DiencephalonForebrain- Diencephalon (con’t)(con’t)
 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
(book figure 16.24).

12. Forebrain- TelencephalonForebrain- Telencephalon
 Cerebral hemispheresCerebral hemispheres
posteriorposterior
 Rhinencephalon anteriorRhinencephalon anterior
 OlfactionOlfaction
 Lower vertebratesLower vertebrates
 Rhinencephalon prominentRhinencephalon prominent
 Hemispheres smallerHemispheres smaller
 Higher vertebratesHigher vertebrates
 Hemispheres increase in sizeHemispheres increase in size
 Olfactory get smallerOlfactory get smaller
Figure 15.13: Front section of cerebral
hemisphere formation (book figure
16.13).

13. Craniate BrainsCraniate Brains
Figure 15.14: Craniate brains.

14. Craniate BrainsCraniate Brains (con’t)(con’t)
Figure 15.15: Dorsal view of craniate brains (book figure 16.14).

15. 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: Globus pallidus of
fish; left cerebral hemisphere
(book figure 16.25).

16. Amphibian CerebrumAmphibian Cerebrum
 Similar pallium and globus pallidusSimilar pallium and globus pallidus
 Split left and right hemispheresSplit left and right hemispheres
Figure 15.17: Globus pallidus of amphibian; left
cerebral hemisphere (book figure 16.25).

17. Reptile CerebrumReptile Cerebrum
 Cerebrum is huge comparedCerebrum is huge compared
to amphibiansto amphibians
 Increase of lateral wallsIncrease of lateral walls
 Pushes into lateral ventriclePushes into lateral ventricle
 Dorsal ventricular ridge formsDorsal ventricular ridge forms
 Receives visual, auditory, andReceives visual, auditory, and
sensory stimulisensory stimuli
Figure 15.18: Globus pallidus of reptile
and bird; left cerebral hemisphere
(book figure 16.25).

18. Bird CerebrumBird Cerebrum
 Similar to reptilesSimilar to reptiles
 Avian ridge (hyperstiatum)Avian ridge (hyperstiatum)
 Stratum of neurons that capped ridgeStratum of neurons that capped ridge
 Processes visual informationProcesses visual information
 Important to instinctive stereotypic behaviorImportant to instinctive stereotypic behavior
 Migration and courtshipMigration and courtship

19. Mammal CerebrumMammal Cerebrum
 Lateral ventricles extremely expandedLateral ventricles extremely expanded
 NeocortexNeocortex
 Higher mental facilitiesHigher mental facilities
 Grooves (sulci)Grooves (sulci)
 Folds (gyrae)Folds (gyrae)
Figure 15.19: Neocortex of mammalian brain.

20. Mammal CerebrumMammal Cerebrum (con’t)(con’t)
Figure 15.20: Ventral view of human brain (book figure 16.17).

21. Mammal CerebrumMammal Cerebrum (con’t)(con’t)
 Portion of primitive brain retainedPortion of primitive brain retained
 Ventral mediallyVentral medially
 Hippocampus- ancient olfactoryHippocampus- ancient olfactory
palliumpallium
 Memory storage?Memory storage?
 Globus pallidum pushed interiorlyGlobus pallidum pushed interiorly
 Basal gangliaBasal ganglia
 Changes in basal gangliaChanges in basal ganglia  motormotor
dysfunctiondysfunction
 Parkinson’s DiseaseParkinson’s Disease
Figure 15.21: Globus pallidus of
human; left cerebral hemisphere
(book figure 16.25).

22. Mammal CerebrumMammal Cerebrum (con’t)(con’t)
Figure 15.22: Sagittal section of the human brain (book figure 16.24).

23. 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 15.23: Cranial nerve locations on the brain.

24. Figure 15.24: Cranial nerve innervation.

25. Figure 15.25: Cranial
nerve innervation.

26. Cranial NervesCranial Nerves (con’t)(con’t)
Figure 15.27: Cranial nerves in 6th
week
embryo.
Figure 15.26: Head organization in 4th
week
embryo (book figure 16.39).

27. Cranial NervesCranial Nerves (con’t)(con’t)

28. Cranial NervesCranial Nerves (con’t)(con’t)

29. Literature CitedLiterature Cited
Figure 15.1, 15.5, 15.9, 15.12, 15.13, 15.15, 15.16, 15.17, 15.18, 15.20, 15.21 & 15.22, 15.27-Figure 15.1, 15.5, 15.9, 15.12, 15.13, 15.15, 15.16, 15.17, 15.18, 15.20, 15.21 & 15.22, 15.27-
Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9thKent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th
ed. McGraw-Hill, 2001.ed. McGraw-Hill, 2001.
Figure 15.2-Figure 15.2- http://people.eku.edu/ritchisong/342notes11.html
Figure 15.3-Figure 15.3-
http://web.lemoyne.edu/~hevern/psy340/lectures/psy340.04.2.ns.structure.html
Figure 15.4-Figure 15.4- http://people.eku.edu/ritchisong/342notes11.html
Figure 15.6-Figure 15.6- http://brain.exp.univie.ac.at/08_vorlesung_ss04/bilder.htm
Figure 15.7-Figure 15.7- http://songweaver.com/brain/index.html
Figure 15.8-Figure 15.8- http://www.medfriendly.com/multiplesclerosis.html
Figure 15.10-Figure 15.10- http://www.csuchico.edu/~pmccaff/syllabi/CMSD%20320/362unit5.html
Figure 15.11-Figure 15.11- http://www.sci.uidaho.edu/med532/epithala.htm
Figure 15.14-Figure 15.14- http://people.eku.edu/ritchisong/342notes11.html
Figure 15.19-Figure 15.19- http://www.aishamusic.com/prayer.htm
Figure 15.23-Figure 15.23-
http://www.besthealth.com/besthealth/bodyguide/reftext/html/nerv_sys_fin.html
Figure 15.24-Figure 15.24- http://www.neurophys.com/EMG/Cranial_Nerves/
Figure 15.25-Figure 15.25- http://www1.appstate.edu/~clarkhm/swallow_distance/page2.htm
Figure 15.27-Figure 15.27- http://isc.temple.edu/neuroanatomy/lab/embryo_new/nerves/