Midbrain + Brainstem In Depth

What does the mesencephalon form?

midbrain + cerebral aqueduct

What does the diencephalon consists of?

epithalamus, thalamus, + hypothalamus

What does the rhombencephalon form?

metencephalon + myelencephalon

What does the metencephalon form?

cerebellum + pons

What does the myelencephalon form?

medulla oblongata

medulla oblongata

connects brain w/ spinal cord, contains nuclei for cranial nerves N VIII, IX, X, XI, XII

olivary nuclei

relay info from spinal cord, red nuclei, diencephalon, + cerebral cortex to cerebellar vermis/cortex

gracile + cuneate nucleus

relay somatic sensory information to ventral posterior nuclei of thalamus

solitary nucleus

receives visceral sensory info from spinal + cranial nerves

cardiovascular center

regulate heart rate, contraction force, + distribution of blood flow

respiratory rhythmicity center

set rate of respiratory movements

reticular formation (medulla oblongata)

regulate vital autonomic nervous system functions

ascending + descending white matter tracts

link brain w/ spinal cord

pons

forms prominent bulge of brain stem; contains nuclei for cranial nerves N V, VI, VII, VIII

transverse fibers

interconnect cerebellar hemispheres

respiratory centers

pneumotaxic + apneustic center; modify output of respiratory centers in medulla oblongata

reticular formation (pons)

autonomic processing of incoming sensations + outgoing motor commands

mesencephalon (midbrain)

contains major nuclei of reticular formation + nuclei for cranial nerves N III, IV

tectum

roof of midbrain; contains corpora quadrigemina

superior colliculi

integrate visual info w/ other sensory input; initiate reflex response to visual stimuli

inferior colliculi

integrate auditory info w/ medial geniculate nuclei; initiate reflex response to auditory stimuli

substantia nigra

regulate activity in the basal nuclei

red nuclei

involuntary control of background muscle tone + limb position

reticular formation (mesencephalon/midbrain)

autonomic processing of incoming sensations and outgoing motor commands; can initiate motor responses to stimuli; helps maintain conscious

cerebral peduncles

connect primary motor cortex w/ motor neurons in brain + spinal cord; carry ascending sensory info to thalamus

epithalamus

anterior portion contains choroid plexus; posterior portion contains pineal gland that secretes melatonin

thalamus

largest mass of nuclei w/in CNS; form walls of diencephalon + surround third ventricle; integrate + relay sensory + motor info; all ascending sensory info synapses in thalamic nuclei before relaying a small portion to cerebrum or brainstem

anterior nuclei

play a role in emotions, memory, + learning; relay info from hypothalamus + hippocampus to cingulate gyrus

medial nuclei

provide awareness of emotional states; integrates sensory info arriving at thalamus from basal nuclei + hypothalamus and projects to frontal lobe

ventral nuclei

relay info from basal nuclei if cerebrum + cerebellum to motor areas of cerebral cortex; project sensory info to primary somatosensory cortex

pulvinar nuclei

integrate sensory info + project it to association areas

lateral geniculate nucleus

receives visual info from eye + projects it to visual cortex

medial geniculate nuclei

receive auditory info from ear + projects it to auditory cortex

lateral group

relay stations in feedback loops that adjust activity in the cingulate gyrus (emotional states) + parietal lobe (integration of sensory info)

hypothalamus

controls autonomic functions; sets appetitive drives + behaviors; sets emotional states w/ limbic system; integrates w/ endocrine system

tuberal area

produce inhibitory + releasing hormones that regulate anterior lobe of pituitary gland

paraventricular nucleus

secretes oxytocin, which stimulates smooth muscle contractions

pre-optic area

regulates body temp via control of autonomic centers in medulla oblongata

sympathetic + parasympathetic autonomic centers

control heart rate + blood pressure via regulation of autonomic centers in medulla oblongata

mammillary bodies

control feeding reflexes

suprachiasmatic nucleus

regulates daily circadian rhythms; receive direct input from retina + output adjusts activities of other centers

supra-optic nucleus

secretes antidiuretic hormone which restricts water loss at kidneys