Brain

Prosencephalon – embryonic forebrain– Telencephalon

Rhinencephalon– Olfactory bulbs– Olfactory tract– Olfactory lobe

Key Points

Identify the meaning of rhin- and olfactory.

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

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

Cerebral Cortex

Voluntary movement (motor)Conscious sensations (sensory)MemoryIntegration (decisions)4 lobes according to skull bones

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

Cerebrum Comparisons

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

Diencephalon

Third Ventricle carries CSFEnters from Lateral ventricle via the

interventricular foramenExits to Fourth ventricle via the cerebral

aqueduct

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

Key Points

What does the term corpora quadrigemina mean?

What structures are included in the corpora quadrigemina that you learned in lab?

Brain

Rhombencephalon Embryonic hindbrain– Myelencephalon

Medulla oblongata Pyramids – crossing of sensory & motor tracts Vital reflexes such as breathing, connection between

brain & spinal cord for ascending & descending pathways

Brain - Rhombencephalon

Metencephalon– Cerebellum – Coordination & balance, quite

large in birds & mammals– Pons – “bridge” between parts of brain

– Fourth Ventricle carries CSF

Key Points

What is the root enceph?Pro? Tel? Di? Mes? Met? Myel? Rhomb?

Cranial Nerves – See Cr. N. Page

I. Olfactory Nerve – Sensory only for smellII. Optic Nerve – Sensory only for visionIII. Oculomotor Nerve – Motor to intrinsic

& extrinsic eye muscles

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

Cranial Nerves

VII. Facial Nerve – motor to facial muscles, salivation, lacrimation, taste

VIII. Acoustic = Vestibulocochlear Nerve – sensory only for hearing & equilibrium

IX. Glossopharangeal Nerve – Motor for swallowing, taste

Cranial Nerves

X. Vagus Nerve – Sensory for taste, motor to visceral of thorax & abdomen for the Parasympathetic Nervous System

XI. Accessory Nerve – amniotes only – Motor for swallowing, head movement

XII. Hypoglossal Nerve – Amniotes only, motor for tongue

Key Points

Which cranial nerves are sensory only?Which cranial nerve is the most important

for internal homeostasis?Which cranial nerves are missing in the

shark?

Key Points

Name the three parts of the embryonic brain. Match these terms with the three parts listed

above:– Hypothalamus– Pons– Cerebral peduncle– Cerebellum– Cerebrum

Key Points

Name the 12 cranial nerves in order.