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Comparative Anatomy Nervous System. Witty/Woods PCB Biology. Primary Brain Vesicles. Prosencephalon (Forebrain) Smell Mesoncephalon (Midbrain) Vision Rhombencephalon (Hindbrain) Hearing. Figure 15.1: Primary brain vessicles (book figure 16.13). Primary Brain Vesicles (con’t).
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Comparative AnatomyNervous System Witty/Woods PCB Biology
Primary Brain Vesicles • Prosencephalon (Forebrain) • Smell • Mesoncephalon (Midbrain) • Vision • Rhombencephalon (Hindbrain) • Hearing Figure 15.1: Primary brain vessicles (book figure 16.13).
Primary Brain Vesicles (con’t) Figure 15.2: Basic brain plan. Figure 15.3: Brain divisions.
Hindbrain • Myelencephalon • Medulla oblongata • Involuntary reflexes • Vagal lobe • Metencephalon • Cerebellum • Roof of metencephalon • Reflex control of skel. muscle • Pons Figure 15.4: Neural tube development.
Hindbrain (con’t) • Lateral ventricles • Two cerebral hemispheres • Posterior choroid plexus • Roof in hindbrain • 4th ventricle tissue • Cerebral spinal fluid • Tela choroidea • Roof of medulla • Thin membrane Figure 15.5: Choroid plexus shown of larval anuran (book figure 16.18).
Divisions and Vesicles Figure 15.6: Divisions of the brain and ventricles numbered.
Midbrain • No subdivisions • Optic lobes • Optic reflex centers • Well developed in birds • Auditory lobes • Caudal to optic lobes • Superior (optic) and inferior (auditory) colliculi- when lobes occur together • Corpora quadrigemina collectively Figure 15.7: Mesoncephalon and tectum region.
Midbrain (con’t) • 3rd ventricle • Optic ventricles- extension to optic lobe • Ventricles disappear in higher phylogeny • Cerebral aqueduct • Restricted passageways • Conducts 3rd and 4th ventricle • Aqueduct of Sylvius when restricted further Figure 15.8: Cerebral aqueduct and ventricles of brain.
Forebrain- Diencephalon • Optic chiasma • Two optic nerves cross • Pituitary gland • Caudal to optic chiasma • Saccus vasculosus • Posterior to pituitary in some fish • Depth receptor Figure 15.9: Regions of the diencephalon of a shark with third ventricle in red (book figure 16.19).
Forebrain- Diencephalon (con’t) • Hypothalamus • Floor of diencephalon • Autonomic nervous system • Thalamus • Walls of diencephalon • 3rd ventricle cavity • Communicates with lateral ventricles • Foramen of Monro Figure 15.10: Medial view of the brain showing thalamus and hypothalamus of the diencephalon.
Forebrain- Diencephalon (con’t) • Epithalamus • Several evaginations • Roof of diencephalon • Paraphysis anteriorly • Epiphyseal complex • Pineal • Photoreceptors • Parapineal • Pineal eye (3rd eye) Figure 15.11: Epithalamus; gross mid-sagittal section of the human brain. Figure 15.12: Pineal in detail (book figure 16.24).
Forebrain- Telencephalon • Cerebral hemispheres posterior • Rhinencephalon anterior • Olfaction • Lower vertebrates • Rhinencephalon prominent • Hemispheres smaller • Higher vertebrates • Hemispheres increase in size • Olfactory get smaller Figure 15.13: Front section of cerebral hemisphere formation (book figure 16.13).
Craniate Brains Figure 15.14: Craniate brains.
Craniate Brains (con’t) Figure 15.15: Dorsal view of craniate brains (book figure 16.14).
Fish Cerebrum • Primitive sensory • Pallium- dorsal area • Motor area • Subpallium- ventral area • Globus pallidus (Striatum) Figure 15.16: Globus pallidus of fish; left cerebral hemisphere (book figure 16.25).
Amphibian Cerebrum • Similar pallium and globus pallidus • Split left and right hemispheres Figure 15.17: Globus pallidus of amphibian; left cerebral hemisphere (book figure 16.25).
Reptile Cerebrum • Cerebrum is huge compared to amphibians • Increase of lateral walls • Pushes into lateral ventricle • Dorsal ventricular ridge forms • Receives visual, auditory, and sensory stimuli Figure 15.18: Globus pallidus of reptile and bird; left cerebral hemisphere (book figure 16.25).
Bird Cerebrum • Similar to reptiles • Avian ridge (hyperstiatum) • Stratum of neurons that capped ridge • Processes visual information • Important to instinctive stereotypic behavior • Migration and courtship
Mammal Cerebrum • Lateral ventricles extremely expanded • Neocortex • Higher mental facilities • Grooves (sulci) • Folds (gyrae) Figure 15.19: Neocortex of mammalian brain.
Mammal Cerebrum (con’t) Figure 15.20: Ventral view of human brain (book figure 16.17).
Mammal Cerebrum (con’t) • Portion of primitive brain retained • Ventral medially • Hippocampus- ancient olfactory pallium • Memory storage? • Globus pallidum pushed interiorly • Basal ganglia • Changes in basal ganglia motor dysfunction • Parkinson’s Disease Figure 15.21: Globus pallidus of human; left cerebral hemisphere (book figure 16.25).
Mammal Cerebrum (con’t) Figure 15.22: Sagittal section of the human brain (book figure 16.24).
Cranial Nerves • Amniotes have 12 • Anamniotes have 10 • Terminal nerve (Nerve 0)- uncommon in humans • Associated with pheromone receptors Figure 15.23: Cranial nerve locations on the brain.
Cranial Nerves (con’t) Figure 15.27: Cranial nerves in 6th week embryo. Figure 15.26: Head organization in 4th week embryo (book figure 16.39).
Literature 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- Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001. Figure 15.2- http://people.eku.edu/ritchisong/342notes11.html Figure 15.3- http://web.lemoyne.edu/~hevern/psy340/lectures/psy340.04.2.ns.structure.html Figure 15.4- http://people.eku.edu/ritchisong/342notes11.html Figure 15.6- http://brain.exp.univie.ac.at/08_vorlesung_ss04/bilder.htm Figure 15.7- http://songweaver.com/brain/index.html Figure 15.8- http://www.medfriendly.com/multiplesclerosis.html Figure 15.10- http://www.csuchico.edu/~pmccaff/syllabi/CMSD%20320/362unit5.html Figure 15.11- http://www.sci.uidaho.edu/med532/epithala.htm Figure 15.14- http://people.eku.edu/ritchisong/342notes11.html Figure 15.19- http://www.aishamusic.com/prayer.htm Figure 15.23-http://www.besthealth.com/besthealth/bodyguide/reftext/html/nerv_sys_fin.html Figure 15.24- http://www.neurophys.com/EMG/Cranial_Nerves/ Figure 15.25- http://www1.appstate.edu/~clarkhm/swallow_distance/page2.htm Figure 15.27- http://isc.temple.edu/neuroanatomy/lab/embryo_new/nerves/