Lecture 14 - The Brain Flashcards
what are the current names for the telencephalone, dienchephalon, and mesencephalon, metancephalon, myelencephalon
whats the other part without an old name
cortex, thalamus/hypothalamus, midbrain, pons, medulla oblongata
cerebellum
what sections of the brain are included in the thalamocortex and brainstem? what parts are their own?
thalamocortex = cortex, thalamus/hypothalamus
brainstem = pons, medulla oblongata, midbrain
cerebellum is its own sections
telencephalon - what region, what is it usually associated with, subdivisions
most anterior region, usually associated with advanced functions
cerebral cortex: grey matter is EXTERNAL (folding pattern during development) - several different lobes
rhinencephalon - olfactory portion and limbic system
basal nuclei (ganglia)
cerebral cortex - appearance and exception
folded into gyri (gyrus: outward fold) an sulci (sulcus: inward fold)
exception = animals like rodents, birds dont have folds in the brain
each gyrus and sulcus has a name
what fold divides the brain into right and left halves?
longitudinal fissure (also called cerebral hemisphere)
how is the cerebral cortex divided, information receiving, lobes
divided into 2 hemispheres, 1 on each side. 5 lobes
primiform/olfactory lobe internally folded = medial to temporal lobe
right information receives information from the left side of body and vice versa
lobes = olfactory, frontal, parietal, temporal, occipital
cerebral lobes - names and what they do
frontal lobe = sensory (caudal part), behaviour (rostral part), voluntary movement, learning
partietal = sensory and association
temporal = audition, equilibrium, association
occipital lobe = visual cortex, association
primiform/olfactory = olfaction, learning, memory, emotions
white matter of cerebral cortex - what does it contain, what do the connections do, what are important parts to remember
contains axons covered with myelin (oligodendrocytes)
connects neurons within same hemisphere –> association fibers (e.g. corona radiata)
connects cortex to brainstem –> projection fibers (e.g. optic radiations)
connects hemispheres together –> commissural fibers (e.g. corpus callosum)
rostal commissure (white matter), corpus callosum (white matter), white matter (tracts)
rhienencephalon - olfactory portion; what are important parts
olfactory portion = olfactory nerve (CN1), olfactory bulb, olfactory peduncles, entorhinal cortex (primiform lobe)
other region of rhinencephalon - what are the parts of it, what is connected and what does that do
limbic system; amygdala, septum, hippocampus
connected to the cortex (cingulate gyrus), thalamus and hypothalamus –> controls emotions and behaviour
well described in primates, not well understood in domestic animals
what happens if the limbic system is overactivated
fear, flight, anger etc happens
basal nuclei - what section is it in and what are the parts of it, function?
subcortical collection of grey matter; parts = caudate nucleus, putamen, globus pallidus, claustrum
function = modulate voluntary movement signals from cortex
thalamus - what is it composed of, what does it receive, what are its functions
composed of several bilateral nuclei (groups of neurons); lateral geniculate nuclei for vision, medial geniculate nuclei for audition
receives all sensory info (except olfaction) and projects to specific area of cortex – clinically linked with cerebral cortex
gets feedback from cortex and basal nuclei
some motor function: cranial part of red nucleus (origin of rubrospinal tract)
thalamocortex - why are they integrated? what are common signs you see here
because the thalamus and cortex have many integrated and overlapping functions, neurologic lesions and injuries in these areas can have similar presentations. These signs include seizures, behavioural changes, motor problems, circling in one direction, etc. These are considered signs of a thalamocortex lesion
what are signs of a thalamocortex lesion
seizures, behavioural changes, motor problems, circling in one direction, etc.
hypothalamus - function, how its grouped
regulates nervous and endocrine system - HR, BP, temp, water balance, food intake, circadian rhythms, emotions
receives and sends connection to thalamus, limbic system, ANS
grouped into severeal nuclei with specific functions
what does the hypothalamus control? secretion?
it controls endocrine secretions of neurohypophysis and adenohypophysis
direct secretion in neurohypophysis; (oxytocin, vasopression)
** know that oxytocin and vasopressin are NTs secreted right into blood stream by hypothalamus
it also secretes releasing hormones that trigger secretion of hormones from adenohypophysis (like ACTH to cortisol?)
effect and action of thyrotropin-releasing hormone (TRH) on adenohypophysis
effect on adenohypophysis = stimulates secretion of thyroid stimulating hormone (TSH)
action on adenohypophysis = increases secretion of thyroid hormones T3 and T4 from thyroid gland
effect and action of corticotropin releasing hormones (CRH) on adenohypophysis
effect on adenohypophysis = stimulates secretion of ACTH
action on adenohypophysis = increases secretion of glucocorticoids, mineralcorticoids and androgens from adrenal gland
effect and action of gonadotropin-releasing hormone (GnRH) on adenohypophysis
effect on adenohypophysis = stimulates secretion of FSH and LH
action on adenohypophysis = production of gametes and secretion of sex steroids
effect and action of prolactin releasing hormones on adenohypophysis
effect on adenohypophysis = stimulates secretion of prolactin
action on adenohypophysis = increases milk production from mammary gland
effect and action of growth-hormone-releasing-hormone on adenohypophysis
effect on adenohypophysis = stimulates secretion of growth hormone
action on adenohypophysis = increases anabolism and organ growth
pineal gland - where is it, what does it do
located dorsally to the thalamus
regulates day/night cycle through release of melatonin
midbrain - purpose of sensory (and other name) and motor portions
sensory (colliculi) = receives visual and auditory signals. mediate movement of the head in reponse to light and sound
motor portion = contraction of pupils (CNIII), gait (caudal part of red nucleus), movement of eye (CNIII, CNIV)
pons - what does it give rise to, function (3)
gives rise to CNV (facial sensation and masticatory muscle movement)
communicates with cerebellum (regulation of movement), some nuclei participate in respiratory control, centres for integration/control of micturition
medulla oblongata - what does it contain, what are its functions
contains nuclei of cranial nerves (6-12)
relays sensory info from spinal cord (tactile, temperature and pain sensation; proprioception)
relays motor information from cortex and brainstem
ascending reticular activating system
cardiovascular and respiratory functions
why are the parts considered part of the brainstem
because the midbrain, pons and medulla oblongata are anatomically continuous, have many related functions (basic control of life supporting activities) and are associated through the reticular formation, theyare often collectively called the brainstem and are functionally considered to be one of the three regions of the brain
brainstem - reticular formation: what is it, what does it do, what is the system called and its responsibility
complex network of neurons (functionally linking parts together)
present in all parts of the brainstem: medulla, pons, midbrain (+thalamus)
receives sensory signal from entire nervous system
projects to cortex via thalamus
ascending reticular activating system (ARAS); sends continuous flow of impulses to cerebral cortex: awakening –> responsible for the level of arousal
what is considered the internet of the brain
brainstem; reticular formation
what do lesions of the ARAS show up as
lethargy, obtundation, stupor, coma
what is the ARAS
ascending reticular activating system
what are some other functions of the reticular formation
locomotion and muscle tone
“true” pain: via poorly defined tracts (spinoreticular) in spinal cord
reflex processes: vomiting, swallowing, sneezing
linked to ANS: micturition, defecation, respiration and HR modulation
brainstem - respiration; specific nuclei
specific nuclei in the medulla and pons are integrated with each other to control inspiration, expiration, breath holding in response to changes in physiological demand
*Respiratory nuclei takes information from lungs/airways to regulate depth of breath and rhythmic
brainstem - cardiovascular regulation; what is it part of, what is included in it (centers) and what do they do
part of ANS
cardiac accelerator center (symapthetic): increases heart rate (chronotrope +) and contraction strength (inotrope +)
cardiac inhibitory center (parasympathetic): through vagal nerve (chronotrope and inotrope -)
vasomotor center: regulates blood pressure. gets info from baroreceptors, carotid sinus (CNIX), aortic arch (CNX)
where is the cerebellum in the brain
most caudal region above the brainstem
cerebellum - what is its function
what symptom can be expect if its not functioning properly, how is it divided
-compares intended movement to actual muscle activity (corrects any disparity, smoothens movement) (so lifting limbs is smooth, integrated and balanced)
-interacts with vestibular system (important for balance)
-Cerebellar ataxia, different from spinal ataxia (couldn’t hold straight line and stumbling) b/c stumbling gait + tremors + over-reaching with steps
- Wobbly cats = panleukopenia in utero, growing cerebellar cells are damaged and leads to cerebellar hypoplasia
- Also calves affected by blue tongue
-divided functionally into regions (cortex, cerebellar nuclei, nodular lobe)
How is the cerebellum divided
2 lateral hemispheres, medial vermis (divides it into two halves)
cerebellum - intended movement vs actual movement, through where
-receives information from cortex = intended movement
-and from spinal cord = actual movement
-sends back correction to cortex
-all through cerebellar peduncles
ataxia - definition, different types, what type of sign is it
ataxia is defined as an inability of an animal to coordinate the activity of its limbs, trunk and/or head in space as it moves. 3 distinct types are recognized clinically. It is a SENSORY (not a motor) sign
proprioceptive/spinal ataxia = spinal cord or brainstem injury to tracts
vestibular ataxia = damage to vestibylar system (braintem, inner ear)
cerebellar ataxia= cerebellum injury/lesions
is ataxia a sensory or motor sign
sensory
what are the three functional regions that we try to narrow down the localization of a lesion to in the brain?
thalamocortex, brainstem, cerebellum
