#8. Cerebellum, Diencephalon, Cerebrum, limbic system Flashcards
Why does the cerebellum have a highly folded surface?
increases the surface area of its outer grey matter, allowing for a greater number of neurons
How much of the brain mass is the cerebellum?
1/10
What separates the cerebellum from the cerebrum?
the tentorium cerebelli and the transverse fissure
What is the vermis?
the constricted central part (the worm)
Do the cerebellar hemispheres have lobes?
yes. the lobes are separated by deep and distinct fissures.
What does the anterior lobe of the cerebellum do?
governs subconscious movement of skeletal muscles
What does the posterior lobe of the cerebellum do?
governs the subconscious movement of skeletal muscles
What are the names of the cerebellar lobes?
anterior lobe, posterior lobe and the flocculonodular lobe
What is the flocculonodular lobe involved in?
equilibrium
What is the cerebellar cortex?
- superficial layer of the cortex
- consists of grey matter in a series of folia
What is folia?
it is grey matter in the cerebellar cortex that looks like leaves on a tree
What is arbor vitae?
it is white matter in the cerebellar cortex that looks like tree branches.
“tree of life”
Where are the cerebellar nuclei?
in the white matter
What do the cerebellar peduncles do and what are they made of?
the attach the cerebellum to the brain stem and they are bundles of white matter tracts
What is in the superior cerebellar peduncles?
axons that extend from the cerebellum to the red nuclei of the midbrain and to several nuclei of the thalamus
Describe the middle cerebellar peduncles
- largest
- axons carry impulses for voluntary movements from pontine nucleus to the cerebellum
What are the 5 different types of axons in the inferior cerebellar peduncles?
- axons of spinocerebellar tracts that carry sensory information from proprioceptors in the trunk and limbs
- axons from vestibular apparatus of inner ear and from vestibular nuclei of medulla and pons. Carry sensory info from proprioceptors in head
- axons from the inferior olivary nucelus of medulla and enter cerebellum and regulate cerebellar neurons
- axons that extend from the cerebellum to the vestibular nuclei of medulla and pons
- axons that extend from cerebellum to reticular formation
What are the functions of the cerebellum?
- primary function of cerebellum is to evaluate how well mvmts initiated by the cerebrum are actually carried out
- if not carried out correctly, the cerebellum detects the discrepancy and sends feedback signals to the cerebral cortex
- the feedback signals help correct the errors, smooth the mvmts and coordinate complex sequences of skeletal mm contractions
- also regulates posture and balance
- very active in learning new skills
What is ataxia?
loss of ability to coordinate mm mvmts.
What are some signs of ataxia?
- changed speech pattern due to uncoordinated speech mm
- staggering or abnormal walking gait
What can cause ataxia?
defenerative diseases (MS, Parkinson’s), trauma, brain tumours, genetic factors, meds side effects, and alcohol
What is the primary purpose of the thalamus?
to relay almost all sensory input to the cerebral cortex.
What is the thalamus made of?
paired oval masses of grey matter organized into nuclei with interspersed tracts of white matter.
What is the intermediate mass?
- variable connection b/w the 2 thalamic masses across the third ventricle
- 70% of people have it.
What is the intermediate mass also called?
the interthalamic adhesion
What is the internal medullary lamina?
- layers of myelinated fibers that appear on transverse sections of the thalamus
- Y-shaped white matter that splits each thalamus
What is the internal capsule?
- axons that connect the thalamus and cerebral cortex pass through it.
- a thick band of white mater lateral to the thalamus
- mostly motor axons
What are the major groups of nuclei on each side of the thalamus?
- anterior nucleus
- medial nuclei
- lateral group
- ventral group (5 nuclei)
- intralaminar nuclei
- midline nucleus
- reticular nucleus
What does the anterior nucleus of the thalamus do?
receives input from the hypothalamus and sends output to the limbic system
What does the anterior nucleus of the thalamus function in?
it functions in emotions and memory
What does the medial nuclei of the thalamus do?
receives input from the limbic system and basal nuclei and send output to the cerebral cortex
What does the medial nuclei of the thalamus function in?
it functions in emotions, learning, memory, and cognition (thinking and knowledge)
What does the lateral group of nuclei of the thalamus do?
receives input from the limbic system, superior colliculi and the cerebral cortex and sends output to the cerebral cortex
What does the lateral group of nuclei of the thalamus function in?
it functions in the expression of emotions.
What are the 5 nuclei in the ventral group of the thalamus?
- ventral anterior nucleus
- ventral lateral nucleus
- ventral posterior nucleus
- lateral geniculate nucleus
- medial geniculate nucleus
What does the ventral anterior nucleus of the thalamus do?
- receives input from the basal nuclei and sends output to the motor areas of the cerebral cortex
- plays a role in movement control
What does the ventral lateral nucleus of the thalamus do?
- receives input from the cerebellum and basal nuclei and sends output to motor areas of the cerebral cortex
- plays a tole in movement control
What does the ventral posterior nucleus of the thalamus do?
-relays impulses for somatic sensations such as touch, pressure, vibration, itch, tickle, temperature, pain and proprioception from the face and body to the cerebral cortex
What does the lateral geniculate nucleus of the thalamus do?
relays visual impulses for sight from the retina to the primary visual area of the cerebral cortex
What does the medial geniculate nucleus of the thalamsus do?
relays auditory impulses for hearing from the ear to the primary auditory area of the cerebral cortex
Where is the intralaminar nuclei of the thalamus?
it lies within the internal medullary lamina and make connections with the reticular formation, cerebellum, basal nuclei, and wide areas of the cerebral cortex
What does the intralaminar nuclei of the thalamus do?
if functions in arousal (activation of the cerebral cortex from the brainstem reticular formation) and integration of sensory and motor information
Where is the midline nucleus of the thalamus located?
-forms a thin band adjacent to the third ventricle
What is the function of the midline nucleus of the thalamus?
it has presumed function in memory and olfaction
Where is the reticular nucleus located?
surrounds the lateral aspect of the thalamus, next to the internal capsule
What does the reticular nucleus do?
monitors, filters and integrates activities of other thalamic nuclei
What are the regions of the hypothalamus?
- mammillary region
- tuberal region
- supraoptic region
- preoptic region
Where is the mammillary region?
it is adjacent to the midbrain; the most posterior part
What does the mammillary region contain?
mammillary bodies and the posterior hypothalamic nuclei
Which sense stops at the mammillary region?
smell
Describe the tuberal region of the hypothalamus
- widest part of the hypothalamus
- infundibulum (stalk connection hypothalamus to pituitary gland)
What is the medial eminence?
where the tuberal region widens
Which nuclei are located in the tuberal region of the hypothalamus?
- dorsomedial nucleus
- ventromedial nucleus
- arcuate nucleus
Where is the supraoptic region of the hypothalamus?
-in front of the optic chiasm
Which nuclei are in the supraoptic region of the hypothalamus?
- paraventricular nucleus
- supraoptic nucleus
- anterior hypothalamic nucleus
- suprachiasmatic nucleus
What does the suprachiasmatic nucleus do?
circadian rhythms
What does the preoptic region of the hypothalamus do?
regulates certain autonomic activities
What does the preoptic region of the hypothalamus contain?
medial and lateral preoptic nuclei
What does the hypothalamus do?
controls many body activities and is one of the major regulators of homeostasis
List the regions in the hypothalamus from anterior to posterior
-preoptic region
-supraoptic region
-tuberal region
mammillary region
What are the important functions of the hypothalams?
- control of ANS (smooth mm, cardiac mm, glands)
- hormone production
- regulation of emotional and behavioral patterns (limbic system)
- regulation of eating and drinking (feeding center, satiation center, thirst center
- control body temperature
- regulation of circadian rhythms and states of consciousness
What is the epithalamus?
-consists of the pineal gland and habenular nuclei
What is the pineal gland a part of and what does it do?
it is a part of the endocrine system and it secretes the hormone melatonin
What does the habenular nuclei do?
it is involved in olfaction, especially emotional responses to odors
Where are the circumventricular organs and what do they do?
- part of the diencephalon
- they lie in the wall of the third ventricle so they can monitor chemical changes in the blood because they lack a blood-brain barrier
- includes part of the hypothalamus, the pineal gland, the pituitary gland
What is the function of CVOs?
to coordinate homeostatic activities of the endocrine and nervous system
(thought to be how HIV enters the brain)
What does the cerebrum do?
provides with with the ability to read, write, speak, make calculations, compose music, to remember the past, plan for the future, imagine….
What is the cerebral cortex?
- it is the region of grey matter that forms the outer rim of the cerebrum.
- only about 2-4 mm thick
- contains billions of neurons arranged in layers
What is the difference between the white and grey matter in the cerebral cortex compared to the white and grey matter in the spinal cord?
The cerebral cortex is reverse from the spinal cord.
spinal cord = grey matter inside, white matter outside
cerebral cortex = grey matter outside, white matter inside
What is the name of the bumps and folds in the cerebral cortex?
gyri/convolutions
What are the deepest grooves in the cerebral cortex called?
fissures
What are the shallower grooves in the cerebral cortex called?
sulci
What is the name of the most prominent fissure and what is its purpose?
the longitudinal fissure and is separates the cerebrum into right and left hemispheres and houses the falx cerebri
What separates the frontal and temporal lobe in the cerebrum?
the lateral cerebral sulcus
What separates the parietal and occipital lobe in the cerebrum?
the perieto-occipital sulcus
What separates the frontal and the parietal lobe in the cerebrum?
the central sulcus
What is the name of the first bump immediately anterior to the central sulcus and what is in it?
the precentral gyrus and it contains the primary motor area of the cerebral coretx
What is the bump immediately posterior to the central sulcus called and what is in it?
it is called the post central gyrus and it contains the somatosensory area of the cerebral cortex
What is a homunculus and how many do we have?
a map of the body in the brain. we have 2, sensory and motor
How many types of tracts are in the cerebral white matter?
3 myelinated tracts
What are the axons that conduct nerve impulses between gryi in the same hemisphere called?
association tracts
What are the axons that conduct nerve impulses from gyri in one cerebral hemisphere to the corresponding gryi in the other hemisphere called?
commissural tracts
What are the groups of commissural tracts called?
- corpus collosum - largest fiber bundle in the brain
- anterior commissure
- posterior commissure
What are the axons that conduct nerve impulses from the cerebrum to lowers parts of the CNS called?
projection tracts
Are projection tracts afferent or efferent? sensory or motor?
The tracts are both afferent motor and efferent sensory
What is the basal nuclei?
3 nuclei that are deep w/in each cerebral hemisphere
What is the Lentiform nucleus
the globus pallidus and the putamen. (part of the basal nuceli)
What are the nuclei in the basal nuclei?
- globus pallidus
- putamen
- caudate nucleus
What is the corpus striatum?
refers to the striated appearance of the internal capsule as it passes among the basal nuclei
What does the basal nuclei do?
receives input from the cerebral cortex and provides output to motor parts of cortex. also has connections with one another
What is the function of the basal nuclei?
- main function is movement
- regulate initiation and termination of mvmts
- suppress unwanted mvmts and regulate mm tone
- control subconscious contractions of skeletal mm
- influence cortical function
What is cortical function?
initiating and terminating cognitive processes like attention, memory and planning.
What can result from dysfunction of circuits between the basal nuclei and the limbic system?
- Parkinson’s disease
- OCS
- schizophrenia
- chronic anxiety
What is the limbic system?
- the emotional brain
- major role in a range of emotions
Other than emotions, what is the limbic system involved in?
olfaction and memory
What is the limbic lobe made of?
- cingulate gyrus
- parahippocampal gyrus
- hippocampus
What is the limbic lobe involved in?
olfaction and memory
What is the dentate gyrus involved in?
new memories and regulating happiness
What is the amygdala involved in?
reward, fear and mating
What is the septal nuclei involved in?
reward and reinforcement
What are the main components of the limbic system?
- limbic lobe
- dentate gyrus
- amygdala
- septal nuclei
- mammillary bodies of the hypothalamus
- anterior and medial nucleus of the thalamus
- olfactory bulbs
- fornix, stria terminalis, stria medullaris, medial forebrain bundle, mammillothalamic tract
