Lesson 8 Flashcards
Cerebellum
- highly folded surface
- increases the surface area of its outer grey matter, allowing for a greater number of neurons
- it accounts for about a tenth of the brain mass but contains about half of the neurons
-things that separate the cerebellum from the cerebrum
-tentorium cerebelli
-transverse fissure
Vermis
the central constricted part of Cerebellum (the worm)
Cerebellum hemispheres
Hemispheres are the wings of the butterfly
Cerebellum hemispheres consist of?
lobes separated by deep and
distinct fissures
- Anterior lobe & Posterior lobe: govern subconscious mvt of
skeletal mm - Flocculonodular lobe:
-involved in equilibrium
Cerebellar cortex
- superficial layer of cortex
- consists of grey matter in a series of folia
Arbor Vitae
Deep to the folia (grey matter) are tracts of white matter
Cerebellar peduncles
- attach the cerebellum to the brain stem
- bundles of white matter
Superior Cerebellar peduncle
- cerebellum to red nuclei (midbrain) + thalamus
Middle Cerebellar peduncle
- largest
- axons carry impulses for voluntary mvts from pontine nucleus to cerebellum
Functions of the cerebellum
- primary function of cerebellum is to evaluate how well movements 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 movements and coordinate complex sequences of skeletal muscle contractions
- also regulates posture and balance
Damage to the cerebellum
ataxia: muscular incoordination
- alcohol inhibits activity of cerebellum so drunks show signs of ataxia
Diencephalon
Thalamus
Hypothalamus
Epithalamus
Thalamus
- relays almost all sensory input to cerebral cortex
- contributes to motor functions by transmitting information from cerebellum and basal nuclei to primary motor area of cerebral cortex
- also relays nerve impulses between different areas of the cerebrum and plays a role in the maintenance of consciousness
Intermediate mass (interthalamic adhesion)
- bridge of grey matter
- joins the right and left thalamus
- found in 70% of brains
Internal medullary lamina
- divides the grey matter of each thalamus
- myelinated axons that enter and leave the various thalamic nuclei
- (y-shaped)
Internal capsule
- thick band of white matter, lateral to the thalamus
Ventral posterior nucleus
- relays impulses for somatic sensations like touch, pressure, vibration, itch, tickle, temperature, pain and proprioception from face and body to cerebral cortex
Lateral geniculate nucleus
- relays visual impulses for sight from the retina to the primary visual area of the cerebral cortex
Medial geniculate nucleus
- relays auditory impulses for hearing from the ear to the primary auditory area of the cerebral cortex
Hypothalamus
- The hypothalamus controls many body activities and is one of the major regulators of homeostasis.
Hypothalamus important functions
- Control of ANS
- production of hormones
- regulates emotional and behavioural patterns
- regulates eating and drinking
- control of body temperature
- regulates circadian rhythm
Hypothalamus
4 regions
- Mammillary region
- Tuberal region
- Supraoptic region
- Preoptic region
Mammillary region
- adjacent to midbrain
- most posterior part
- mammillary bodies (memories)
- posterior hypothalamic nuclei
Tuberal region
- widest part of hypothalamus
- dorsomedial nucleus
- ventromedial nucleus
- arcuate nucleus
- infundibulum (conect pituitary to hypothalamus)
- medial eminence
Supraoptic region
- in front of optic chiasm
- paraventricular nucleus
- supraoptic nucleus
- anterior hypothalamus
- suprachiasmatic nucleus (circadian rhythym)
Preoptic region
- regulates certain autonomic activities
- contains medial and lateral preoptic nuclei
Epithalamus
- consists of pineal gland and habenular nuclei
- the pineal gland is part of the endocrine system because it secretes the hormone melatonin
- habenular nuclei are involved in olfaction, especially emotional responses to odors
Circumventricular Organs (CVOs)
- found throughout the brain, including parts of the hypothalamus, pineal gland, pituitary gland, and
medulla - these areas are clustered around the third and forth ventricles
- CVOs lack a blood-brain barrier (BBB) which allows them to better communicate with the rest of the body
CVO’s Function
- function: coordinate homeostatic activities of endocrine and nervous system
- CVOs are thought to be how HIV enters the brain
CEREBRUM
- it provides us with the ability to read, write, speak make calculations, compose music, to remember the past, plan for the future, imagine…
Cerebral cortex
- region of grey matter that forms the outer rim
- only about 2-4 mm thick
- contains billions of neurons arranged in layers
Parts of the cerebrum
- gyri/convolutions
-the folds - fissures
-deepest grooves
between the folds - sulci
-shallower grooves between
the folds - Longitudinal fissure
-the most prominent fissure
-separates the cerebrum into
left and right hemispheres
-within the longitudinal fissure
is the falx cerebri
Lobes of the cerebrum
- frontal lobe
- parietal lobe
- temporal lobe
- occipital lobe
Lobes of the central sulcus
- frontal lobe
- parietal lobe
Lobes of the lateral cerebral sulcus
- frontal lobe
- temporal lobe
Lobes of the Parieto-occipital sulcus
- parietal lobe
- occipital lobe
Postcentral gyrus
- located immediately posterior to the central sulcus
- contains the primary somatosensory area of the cerebral cortex
Cerebral white matter
There are mainly 3 types of myelinated tracts:
- Association tracts
- Commissural tracts
- Projections tracts
Association tracts
axons that conduct nerve impulses between
gyri in same hemisphere
Commissural tracts
- axons that conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other cerebral hemisphere
Commissural tract 3 major groups
- Corpus callosum – largest fiber bundle in the brain
- Anterior commissure
- Posterior commissure
Projections tracts
- contains axons that conduct nerve impulses from the cerebrum to lower parts of the CNS (thalamus, brainstem or spinal cord) or vice versa
Basal Ganglia/Nuclei
-3 nuclei that are deep within each cerebral hemisphere
1.Globus pallidus
2.Putamen
3. Caudate nucleus
Corpus striatum refers to the striated appearance of the internal capsule as it passes among the basal nuclei
Function of basal ganglia/nuclei
- regulate initiation and termination of movements
- suppress unwanted mvts and regulate muscle tone
- control subconscious contractions of skeletal mm
- influence cortical function (initiating and terminating cognitive processes like attention, memory and planning)
Dysfunction of circuits between basal nuclei and
limbic system
- Parkinson’s disease
- Obsessive-compulsive disorder
- Schizophrenia
- Chronic anxiety
Limbic system
- emotional brain
- plays a major role in a range of emotions
- involved in olfaction and memory
Limbic lobe
olfaction and memory
Dentate gyrus
new memories, regulate happiness
Septal nuclei
reward, reinforcement
Amygdala
reward, fear, mating
