Brain Development and Anatomy 1

Early development

formation of the neural tube: neural groove and neural folds

cranial expansions [vesicles]

prosencephalon [forebrain]

mesencephalon [midbrain]

rhombencephalon [hindbrain]

flexures

cephalic

pontine

cervical

ventricles

development of the vesicles

forebrain

olfactory bulbs [rhinencephalon]

cerebral hemispheres [telencephalon]

optic vesicles

diencephalon

pineal body

infundibulum

mesencephalon

tectum [forms optic lobes in lower vertebrates]

corpora quadrigemina

hindbrain

cerebellum

pons

medulla oblongata

[metencephalon + myelencephalon]

Brain stem

medulla oblongata

fourth ventricle

inferior velum forms its roof

ascending and descending tracts

decussation of the pyramids

respiratory, vasomotor, cardiac centers

nuclei for cranial nn IX–XII

olivary nuclei [relay centers between cerebral cortex/basal ganglia and cerebellum]

reticular formation

pons

floor of the fourth ventricle

pontine nuclei

middle cerebellar peduncles

nuclei for cranial nn V–VIII

reticular formation

corticospinal, corticobulbar, and corticopontine tracts

Mesencephalon

midbrain [mesencephalon]

cerebral aqueduct (aqueduct of Sylvius)

cerebral peduncles

nuclei for cranial nn III–IV and anterior part of V

red nucleus and rubrospinal tract

superior cerebellar peduncle

corpora quadrigemina

superior colliculi [visual, auditory, tactile reflex centers]

inferior colliculi [auditory reflex centers]

Cerebellum

anatomy

peduncles

superior... midbrain

middle... pons

inferior (restiform body)... medulla oblongata

cerebellar hemispheres

vermis

cerebellar cortex

folia cerebelli

fissures

arbor vitae

layers

outer molecular layer [input]

Purkinje cell layer [output]

to deep cerebellar and lateral vestibular nuclei

inner granular layer [input]

functional considerations

functions quickly with no storage

coordination of somatic motor activity

regulation of muscle tone

maintenance of equilibrium

lesions

do not result in paralysis

ataxia

hyotonia and asthenia

tremors and nystagmus

ipsilateral representation

Forebrain

diencephalon

rostral limit is the interventricular foramina (foramina of Monro)

third ventricle

lateral walls are the thalami

intermediate mass [variable, ~60%]

roof is the epithalamus

floor is the hypothalamus

thalmus

major sensory center

crude, uncritical consciousness [the reptilian brain]

epithalamus

choroid plexus and the production of cerebrospinal fluid (CFS)

pineal body

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