Brain

1. Brain • Prosencephalon – embryonic forebrain • Telencephalon • Rhinencephalon • Olfactory bulbs • Olfactory tract • Olfactory lobe

4. Key Points • Identify the meaning of rhin- and olfactory.

5. Brain - Prosencephalon • Telencephalon • Cerebral hemispheres • Paleostriatum – primary region in fish, primarily involved with olfactory reflexes • Neostriatum – beginning with reptiles, more complex and paleostriatum becomes buried • Hyperstriatum – primarily in birds responsible for stereotypical behavior such as migration, courting, nesting

7. Brain - Prosencephalon • Telencephalon • Cerebral hemispheres = Cerebrum • Corpus striatum = Basal nuclei – remnants of paleostriatum buried in mammalian brain, responsible for stereotyped & repetitive movements • Cortex – starting with reptiles, billions of neurons that must be folded to fit in skull in mammals

10. Cerebral Cortex • Voluntary movement (motor) • Conscious sensations (sensory) • Memory • Integration (decisions) • 4 lobes according to skull bones

12. Brain - Prosencephalon • Telencephalon • Lateral Ventricles • Cavities in brain that contain • Cerebrospinal fluid (CSF) • Formed from blood vessels called choroid plexus • Circulates around CNS providing cushion, protection, nutrients

14. Cerebrum Comparisons

18. Brain - Prosencephalon • Diencephalon • Epithalamus - Pineal body is light receptor in agnathans & endocrine in gnathostomes • Thalamus – intermediate mass/adhesion; sensory relay • Hypothalamus – optic chiasma, infundubular stalk for pituitary gland; functions as endocrine, regulates ANS, emotions, water balance, thermostat, hunger, satiety

23. Diencephalon • Third Ventricle carries CSF • Enters from Lateral ventricle via the interventricular foramen • Exits to Fourth ventricle via the cerebral aqueduct

25. Brain • Mesencephalon – embryonic midbrain, but term used in adult too • Optic lobes – especially well developed in birds • Auditory lobes – auditory reflexes • Corpora Quadrigemina • Cerebral Peduncles – motor tracts • Cerebral Aqueduct – for CSF

26. Key Points • What does the term corpora quadrigemina mean? • What structures are included in the corpora quadrigemina that you learned in lab?

31. Brain • Rhombencephalon Embryonic hindbrain • Myelencephalon • Medullaoblongata • Pyramids – crossing of sensory & motor tracts • Vital reflexes such as breathing, connection between brain & spinal cord for ascending & descending pathways

35. Brain - Rhombencephalon • Metencephalon • Cerebellum – Coordination & balance, quite large in birds & mammals • Pons – “bridge” between parts of brain • Fourth Ventricle carries CSF

40. Key Points • What is the root enceph? • Pro? Tel? Di? Mes? Met? Myel? Rhomb?

41. Cranial Nerves – See Cr. N. Page • I. Olfactory Nerve – Sensory only for smell • II. Optic Nerve – Sensory only for vision • III. Oculomotor Nerve – Motor to intrinsic & extrinsic eye muscles

46. Cranial Nerves • IV. Trochlear Nerve – motor to extrinsic eye muscles • V. Trigeminal nerve – mixed nerve, motor to mastication & pharyngeal arch muscles, sensory to nose & mouth • VI. Abducens nerve – motor to extrinsic eye muscles