Title: Comparative Anatomy Nervous System
1Comparative AnatomyNervous System
- Kardong
- Chapter 16
- Part 15
2Primary Brain Vesicles
- Prosencephalon (Forebrain)
- Smell
- Mesoncephalon (Midbrain)
- Vision
- Rhombencephalon (Hindbrain)
- Hearing
Figure 15.1. Primary brain vesicles (book figure
16.25).
3Primary Brain Vesicles (cont.)
Figure 15.2. Basic brain plan.
Figure 15.3. Brain divisions.
4Hindbrain
- Myelencephalon
- Medulla oblongata
- Involuntary reflexes
- Vagal lobe
- Metencephalon
- Cerebellum
- Roof of metencephalon
- Reflex control of
- skeletal muscle
- Pons - Floor of metencephalon - relay station
of sensory and motor tracts between spinal cord
and cerebrum
Figure 15.4. Regional divisions of the brain
(book figure 16.25).
5Hindbrain (cont.)
- 4th ventricle
- Cavity of hindbrain
- Posterior choroid plexus
- Roof in hindbrain
- 4th ventricle tissue
- Cerebrospinal fluid
- Tela choroidea
- Roof of medulla
- Thin membrane
Figure 15.5. Choroid plexus shown in a larval
anuran.
6Brain Divisions/Vesicles
Figure 15.6. Regions of the vertebrate brain
(Fig. 16.32)
7Midbrain
- No subdivisions
- Roof tectum floor - tegmentum
- 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. Mesencephalon and tectum region.
8Midbrain (cont.)
- 3rd ventricle
- Cavity of midbrain
- Cerebral aqueduct
- Restricted passageways
- Conduit between
- 3rd and 4th ventricle
- Aqueduct of Sylvius when restricted further
Figure 15.8. Cerebral aqueduct and ventricles of
brain.
9Forebrain - 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.
10Forebrain- Diencephalon (cont.)
- Hypothalamus
- Floor of diencephalon
- Thalamus
- Walls of diencephalon
- 3rd ventricle cavity
- Communicates with lateral ventricles
- Foramen of Monro
- (actually 2 foramina)
Figure 15.10. Medial view of the brain showing
thalamus and hypothalamus of the diencephalon.
11Forebrain- 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 (see book figure
16.37).
12Forebrain- Telencephalon
- Cerebral hemispheres posterior
- Rhinencephalon anterior
- Olfaction
- Lower vertebrates
- Rhinencephalon prominent
- Hemisphere smaller
- Higher vertebrates
- Hemispheres increase in size
- Olfactory get smaller
Figure 15.13. Frontal section of cerebral
hemisphere formation.
13Evolution of Vertebrate Brain
Figure 15.14. Phylogenetic enlargement of
vertebrate brains (see Fig. 16.33).
14Vertebrate Brains (cont.)
Figure 15.15. Dorsal view of vertebrate brains.
15Telencephalon Terminology
16Fish Cerebrum
- Primitive sensory
- Pallium- dorsal area
- Motor area
- Subpallium- ventral area
- Globus pallidus (striatum)
-
Figure 15.16. Embryonic development of the
telencephalon (Book figure 16.42.
17Amphibian Cerebrum
- Similar pallium and globus pallidus
- Split left and right hemispheres
Figure 15.17. Globus pallidus of amphibian left
cerebral hemisphere.
18Reptile 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.
19Bird Cerebrum
- Similar to reptiles
- Avian ridge (hyperstriatum)
- Stratum of neurons that capped ridge
- Processes visual information
- Important to instinctive stereotypic
- behavior
- Migration and courtship
Figure 15.19. Globus pallidus of reptile and
bird left cerebral hemisphere.
20Mammalian Cerebrum
- Lateral ventricles extremely expanded
- Neocortex
- Higher mental facilities
- Grooves (sulci)
- Folds (gyrae)
Figure 15.20. Neocortex of mammalian brain.
21Mammalian Cerebrum (cont.)
Figure 15.21. Ventral view of human brain (see
book Fig 16.36).
22Mammalian 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 15.22. Globus pallidus of human left
cerebral hemisphere
23Mammalian Cerebrum (cont.)
Figure 15.23. Sagittal section of the human brain
(book Fig. 16.37).
24Cranial Nerves
- Amniotes have 12
- Anamniotes have 10
- Terminal nerve (Nerve 0)- uncommon in humans
- Associated with pheromone receptors
Figure 15.24. Cranial nerve locations on the
brain.
25Figure 15.25. Cranial nerve innervation (book
Fig. 16.15).
26Figure 15.26. Cranial nerve innervation (book
Fig. 16.15).
27Cranial Nerves (cont.)
Figure 15.27. Cranial nerves in 6th week embryo.
Figure 15.28. Head organization in 4th week
embryo (book figure 16.39).
28Cranial Nerves (cont.)
29Cranial Nerves (cont.)