Chp 13.4-13.7 Pons, Medulla, Diencephalon, Cerebellum, Midbrain Flashcards
2 major features of medulla oblongata
olive and pyramids
Pyramids
contain tracts of motor fibers that originate in cerebral cortex
3 components of medulla oblongata
autonomic centers, relay stations, nuclei associated with five cranial nerves
olive
prominent olive-shaped bulge that follows the contours of the olivary nucleus
medulla oblongata
all communication passes through here, contains ascending (sensory) and descending (motor) tracts
ascending tracts
sensory
descending tracts
motor
autonomic centers
control vital functions
relay stations
located along sensory and motor pathways
pons
links the cerebellum with midbrain, diencephalon, cerebrum, medulla oblongata, spinal cord
3 parts of pons
ascending and descending tracts, respiratory centers, reticular formation
reticular formation
loosely organized mass of gray matter, contains nuclei that regulate autonomic functions, extends from the medulla to midbrain
two primary functions of cerebellum
adjusting the postural muscles of the body
programming and fine-tuning movements controlled at the conscious and subconscious levels
ataxia
result from trauma or stroke or drugs or alcohol
damage to cerebellum
affects muscle coordination
cerebellum
automatic processing center
monitors proprioceptive, visual, tactile, balance, auditory sensations
cerebellum anatomy
large anterior and posterior lobes
two hemispheres
covered by cerebellar cortex
primary fissure
separates anterior and posterior lobes
vermis
separates two hemipsheres
it is a narrow band of cortex
cerebellar cortex
thin layer of gray matter folia less prominent than cerebral folds inner granular layer outer molecular layer arbor vitae cerebellar penduncles
folia (leaves)
folds of the surface of cerebeller cortex
outer molecular layer of cerebellar cortex
purkinje cells
receive input from 200,00 synapses (more than any other type of cell in brain)
relay motor commands
only axons leave the cortex are purkinje cells
arbor vitae
“tree of life”
branching array of white matter of the cerebellum
cerebellar penduncles
collections of tracts
links the cerebellum with the brain stem, cerebrum and spinal cord
three on each side (superior, middle, inferior)
superior peduncles
carries most of cerebellar output
middle peduncles
carries most cerebellar input
midbrain
most complex and integrative portion of the brainstem
can direct complex motor patterns at the subconscious level
influences level of activity in entire nervous system.
7 components of the midbrain
corpora quadrigemina, reticular activating system (RAS), red nucleus, substantia nigra, cerebral penduncles, tectum, tegmentum
2 parts of corpora quadrigemina
superior colliculus, inferior colliculus
corpora quadrigemina
two pairs of sensory nuclei located in the roof of the midbrain
superior colliculus
receives visual inputs from thalamus
controls reflex movements of eyes, head and neck in response to visual stimuli
inferior colliculus
receives auditory data from nuclei in medulla and pons
controls reflex movements of head, neck and truck in response to auditory inputs
substantia nigra
contains dark pigemented cells,
adjust activity in the basal nuclei of the cerebrum
damaged in a patient with Parkinson’s Disease
cerebral penduncles
nerve fiber bundles on ventrolateral surfaces of midbrain
contain descending fibers that:
reach the cerebellum using pons
carry voluntary motor commands from cerebral hemispheres
reticular activating system (RAS)
specialized part of the reticular formation
stimulation of the RAS increases alertness.
damage to the RAS produces unconsciousness
red nucleus
receives information from cerebrum and cerebellum
issues subconscious motor commands that affect upper limb position and muscle tone.
tectum
roof of the midbrain, region posterior to the cerebral aqueduct
tegmentum
region anterior to the cerebral aqueduct
3 regions of diencephalon
epithalamus, thalamus, hypothalamus
diencephalon
anterior limit marked by the anterior commissure
anterior commissure
tract that interconnects cerebral hemispheres and location of the optic chiasm
optic chiasm
where optic nerves connect to the brain
epithalamus
contains pineal gland
roof of the diencephalon
superior to the third ventricle
anterior portion contains area of choroid plexus
pineal gland
endocrine structure that secretes melatonin (day-night cycle)
thalamus
final relay point for ascending sensory information that will be projected to the cerebral cortex
acts as a filter
each region contains nuclei that connect to specific regions of cerebral cortex
3 parts of thalamus
lateral geniculate nucleus, medial geniculate nucleus, interthalamic adhesion
lateral geniculate nucleus
receives visual information over the optic tract
sends signals to midbrain and occipital lobe
medial geniculate nucleus
relays auditory information from specialized receptors of the inner ear to auditory area in cerebral cortex
interthalamic adhesion
protection of gray matter extending into the third ventricle from the thalamus on either side
no fibers cross midline
absent in about 20% of brains
hypothalamus may be stimulated by
- sensory information from the cerebrum, brainstem, and spinal cord
- changes in the composition of the CSF and interstitial fluid
- chemicals in the circulated blood
(blood rapidly enters the hypothalamus, since there is no blood brain barrier)
4 hypothalamic nuclei
autonomic centers, preoptic area, suprachiasmatic nucleus, hormonal centers
automatic centers of hypothalamus
control cardiovascular and vasomotor centers of the medulla
preoptic area
regulates body temp by coordinating adjustments in blood flow and sweat gland activity
suprachiasmatic nucleus
coordinates day-night
hormonal centers
secreate chemical messengers to the anterior pituitary and produce two hormones released at the posterior pituitary
2 hypothalamus structures
infundibulum and mamillary bodies
infundibulum
narrow stalk extending inferiorly from the hypothalamus
connects the floor of the hypothalamus to the pituitary gland.
mammilary bodies
control feeding reflexes