Comparative Anatomy Nervous System Kardong Chapter 16 Part 15

Primary Brain Vesicles Prosencephalon (Forebrain) Prosencephalon (Forebrain) Smell Smell Mesoncephalon (Midbrain) Mesoncephalon (Midbrain) Vision Vision Rhombencephalon (Hindbrain) Rhombencephalon (Hindbrain) Hearing Hearing Figure Primary brain vesicles (book figure 16.25).

Figure Basic brain plan. Primary Brain Vesicles (cont’d.) Figure Brain divisions.

Hindbrain Myelencephalon Myelencephalon Medulla oblongata Medulla oblongata Involuntary reflexes Involuntary reflexes Vagal lobe Vagal lobe Metencephalon Metencephalon Cerebellum Cerebellum Roof of metencephalon Roof of metencephalon Reflex control of Reflex control of skeletal muscle skeletal muscle Pons - Floor of metencephalon - relay station of sensory and motor tracts between spinal cord and cerebrum Pons - Floor of metencephalon - relay station of sensory and motor tracts between spinal cord and cerebrum Figure Regional divisions of the brain (book figure 16.25).

Hindbrain (cont’d.) 4th ventricle 4th ventricle Cavity of hindbrain Cavity of hindbrain Posterior choroid plexus Posterior choroid plexus Roof in hindbrain Roof in hindbrain 4 th ventricle tissue 4 th ventricle tissue Cerebrospinal fluid Cerebrospinal fluid Tela choroidea Tela choroidea Roof of medulla Roof of medulla Thin membrane Thin membrane Figure Choroid plexus shown in a larval anuran.

Brain Divisions/Vesicles Figure Regions of the vertebrate brain (Fig )

Midbrain No subdivisions No subdivisions Roof – tectum; floor - tegmentum Optic lobes Optic lobes Optic reflex centers Optic reflex centers Well developed in birds Well developed in birds Auditory lobes Auditory lobes Caudal to optic lobes Caudal to optic lobes Superior (optic) and inferior (auditory) colliculi- when lobes occur together Superior (optic) and inferior (auditory) colliculi- when lobes occur together Corpora quadrigemina collectively Corpora quadrigemina collectively Figure Mesencephalon and tectum region.

Midbrain (cont’d.) 3 rd ventricle 3 rd ventricle Cavity of midbrain Cavity of midbrain Cerebral aqueduct Cerebral aqueduct Restricted passageways Restricted passageways Conducts between Conducts between 3 rd and 4 th ventricle Aqueduct of Sylvius when restricted further Aqueduct of Sylvius when restricted further Figure Cerebral aqueduct and ventricles of brain.

Forebrain - Diencephalon Optic chiasma Optic chiasma Two optic nerves cross Two optic nerves cross Pituitary gland Pituitary gland Caudal to optic chiasma Caudal to optic chiasma Saccus vasculosus Saccus vasculosus Posterior to pituitary in some fish Posterior to pituitary in some fish Depth receptor Depth receptor Figure Regions of the diencephalon of a shark with third ventricle in red.

Forebrain- Diencephalon (cont’d.) Hypothalamus Hypothalamus Floor of diencephalon Floor of diencephalon Thalamus Thalamus Walls of diencephalon Walls of diencephalon 3 rd ventricle cavity 3 rd ventricle cavity Communicates with lateral ventricles Communicates with lateral ventricles Foramen of Monro Foramen of Monro Figure Medial view of the brain showing thalamus and hypothalamus of the diencephalon.

Forebrain- Diencephalon (cont.’d) Epithalamus Epithalamus Several evaginations Several evaginations Roof of diencephalon Roof of diencephalon Paraphysis anteriorly Paraphysis anteriorly Epiphyseal complex Epiphyseal complex Pineal Pineal Photoreceptors Photoreceptors Parapineal Parapineal Pineal eye (3 rd eye) Pineal eye (3 rd eye) Figure Epithalamus; gross mid- sagittal section of the human brain. Figure Pineal in detail (see book figure 16.37).

Forebrain- Telencephalon Cerebral hemispheres posterior Cerebral hemispheres posterior Rhinencephalon anterior Rhinencephalon anterior Olfaction Olfaction Lower vertebrates Lower vertebrates Rhinencephalon prominent Rhinencephalon prominent Hemisphere smaller Hemisphere smaller Higher vertebrates Higher vertebrates Hemispheres increase in size Hemispheres increase in size Olfactory get smaller Olfactory get smaller Figure Frontal section of cerebral hemisphere formation.

Evolution of Vertebrate Brain Figure Phylogenetic enlargement of vertebrate brains (see Fig ).

Vertebrate Brains (cont’d.) Figure Dorsal view of vertebrate brains.

Fish Cerebrum Primitive sensory Primitive sensory Pallium- dorsal area Pallium- dorsal area Motor area Motor area Subpallium- ventral area Subpallium- ventral area Globus pallidus (striatum) Globus pallidus (striatum) Figure Embryonic development of the telencephalon (Book figure

Amphibian Cerebrum Similar pallium and globus pallidus Similar pallium and globus pallidus Split left and right hemispheres Split left and right hemispheres Figure Globus pallidus of amphibian; left cerebral hemisphere.

Reptile Cerebrum Cerebrum is huge compared to amphibians Cerebrum is huge compared to amphibians Increase of lateral walls Increase of lateral walls Pushes into lateral ventricle Pushes into lateral ventricle Dorsal ventricular ridge forms Dorsal ventricular ridge forms Receives visual, auditory, and sensory stimuli Receives visual, auditory, and sensory stimuli Figure Globus pallidus of reptile and bird; left cerebral hemisphere.

Bird Cerebrum Similar to reptiles Similar to reptiles Avian ridge (hyperstriatum) Avian ridge (hyperstriatum) Stratum of neurons that capped ridge Stratum of neurons that capped ridge Processes visual information Processes visual information Important to instinctive stereotypic Important to instinctive stereotypicbehavior Migration and courtship Migration and courtship Figure Globus pallidus of reptile and bird; left cerebral hemisphere.

Mammalian Cerebrum Lateral ventricles extremely expanded Lateral ventricles extremely expanded Neocortex Neocortex Higher mental facilities Higher mental facilities Grooves (sulci) Grooves (sulci) Folds (gyrae) Folds (gyrae) Figure Neocortex of mammalian brain.

Mammalian Cerebrum (cont.’d) Figure Ventral view of human brain (see book Fig 16.36).

Mammalian Cerebrum (cont.’d) Portion of primitive brain retained Portion of primitive brain retained Ventral medially Ventral medially Hippocampus- ancient olfactory pallium Hippocampus- ancient olfactory pallium Memory storage? Memory storage? Globus pallidum pushed interiorly Globus pallidum pushed interiorly Basal ganglia Basal ganglia Changes in basal ganglia  motor dysfunction Changes in basal ganglia  motor dysfunction Parkinson’s Disease Parkinson’s Disease Figure Globus pallidus of human; left cerebral hemisphere

Mammalian Cerebrum (cont.’d) Figure Sagittal section of the human brain (book Fig ).

Cranial Nerves Amniotes have 12 Amniotes have 12 Anamniotes have 10 Anamniotes have 10 Terminal nerve (Nerve 0)- uncommon in humans Terminal nerve (Nerve 0)- uncommon in humans Associated with pheromone receptors Associated with pheromone receptors Figure Cranial nerve locations on the brain.

Figure Cranial nerve innervation (book Fig ).

Figure Cranial nerve innervation (book Fig ).

Cranial Nerves (cont.’d) Figure Cranial nerves in 6 th week embryo. Figure Head organization in 4 th week embryo (book figure 16.39).

Cranial Nerves (cont.’d)