Comparative Anatomy Nervous System

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Comparative AnatomyNervous System

• Note Set 12
• Chapter 16

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Primary Brain Vesicles

• Prosencephalon (Forebrain)
• Smell
• Mesoncephalon (Midbrain)
• Vision
• Rhombencephalon (Hindbrain)
• Hearing

Figure 15.1 Primary brain vessicles (book figure
16.13).
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Primary Brain Vesicles (cont)
Figure 15.2 Basic brain plan.
Figure 15.3 Brain divisions.
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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.
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Hindbrain (cont)

• 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).
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Divisions and Vesicles
Figure 15.6 Divisions of the brain and
ventricles numbered.
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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.
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Midbrain (cont)

• 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.
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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).
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Forebrain- Diencephalon (cont)

• 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.
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Forebrain- Diencephalon (cont)

• 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).
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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).
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Craniate Brains
Figure 15.14 Craniate brains.
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Craniate Brains (cont)
Figure 15.15 Dorsal view of craniate brains
(book figure 16.14).
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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).
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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).
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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).
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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

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Mammal Cerebrum

• Lateral ventricles extremely expanded
• Neocortex
• Higher mental facilities
• Grooves (sulci)
• Folds (gyrae)

Figure 15.19 Neocortex of mammalian brain.
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Mammal Cerebrum (cont)
Figure 15.20 Ventral view of human brain (book
figure 16.17).
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Mammal Cerebrum (cont)

• 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
• Parkinsons Disease

Figure 15.21 Globus pallidus of human left
cerebral hemisphere (book figure 16.25).
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Mammal Cerebrum (cont)
Figure 15.22 Sagittal section of the human brain
(book figure 16.24).
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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.
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Figure 15.24 Cranial nerve innervation.
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Figure 15.25 Cranial nerve innervation.
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Cranial Nerves (cont)
Figure 15.27 Cranial nerves in 6th week embryo.
Figure 15.26 Head organization in 4th week
embryo (book figure 16.39).
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Cranial Nerves (cont)
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Cranial Nerves (cont)
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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/342n
  otes11.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/342n
  otes11.html
• Figure 15.6- http//brain.exp.univie.ac.at/08_vorl
  esung_ss04/bilder.htm
• Figure 15.7- http//songweaver.com/brain/index.htm
  l
• Figure 15.8- http//www.medfriendly.com/multiplesc
  lerosis.html
• Figure 15.10- http//www.csuchico.edu/pmccaff/syl
  labi/CMSD20320/362unit5.html
• Figure 15.11- http//www.sci.uidaho.edu/med532/epi
  thala.htm
• Figure 15.14- http//people.eku.edu/ritchisong/342
  notes11.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/sw
  allow_distance/page2.htm
• Figure 15.27- http//isc.temple.edu/neuroanatomy/l
  ab/embryo_new/nerves/