NEURO 2 Flashcards
what is the limbic system?
functional group that establishes emotion states, links conscious functions of cerebral cortex with autonomic functions of brain stem, faciliates memory storage & retrieval- also known as the motivational system
what happens if there is damage to hippocampus?
memory disorder & neurodegenerative diseases e.g. alzheimers
what are the components of limbic system?
amygdaloid body, limbic lobe of cerebral hemisphere, fornx, anterior nucleus, reticular formation, hypothalamus
what is the function of the amygdaloid body?
interfaces limbic system, cerebrum and sensory systems- interfaces limbic system, cerebrum and sensory systems- role in heartrate & sympathetic system
what makes up the limbic lobe?
cingulate gyrus, dentate gyrus, parahippocampal gyrus (conceals the hippocampus), hippocampus
what is the fornix?
tract of white matter, connects hippocampus with hypothalamus
what is the role of the anterior nucleus of thalamus?
relays information from mamillary body to cingulate gyrus
what is the role of the reticular formation?
stimulation or inhibition affects emotions (rage, fear, pain, sexual arousal, pleasure)
what is the role of hypothalamus?
responsible for controlling functions such as hunger, thirst, emotions, body temperature regulation and circadian rhythms
what is the role of hippocampus?
plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation
what does the brainstem include?
midbrain (mesencephalon), pons (part of metencephalon) & medulla oblongata (myelencephalon)
what levels is midbrain at?
Dorsal & ventral regions at level of cerebral/mesencephalic aqueduct
what is at the tectum (roof) of dorsal midbrain?
superior (involved in vision) & inferior colliculi (auditory)
what makes up the walls & floor of midbrain?
substantia nigra (involved in parkinsons), red nucleus, reticular formation (groups of nuclei- automatic processing centre)
what is at the tegmentum (covering) of ventral midbrain?
crus cerebri
what is the role of the superior & inferior colliculi?
superior= preliminary visual processing and control of eye movements- inferior= auditory processing
what does the tegmentum of mesencephalon contain?
red nucleus & substantia nigra (neuromalanin)- contains ascending & descending tract, relay nuclei & nuclei of cranial nerves III & IV
what are the cerebral peduncles?
bundles of axons on ventrolateral surfaces containing descending fibers to cerebellum & corticospinal fibres
what are the structures of the mesencephalon?
tectum, tegmentum, cerebral peduncles, reticular formation
what does the pons consist of?
pontine tegmentum & basilar pons (bulbous structure on anterior aspect of pons
what does the pons provide links to?
Links cerebellum with mesencephalon, diencephalon, cerebrum and spinal cord
what are the 4 groups of nuclei in pons?
sensory & motor nuclei of cranial nerves (v, vi, vii, viii), nuclei involved in respiration, nuclei & tracts, ascending + descending & transverse tracts
what does the basilar pons consist of?
large bundle of transversely orientated fibres that enter the cerebellum- middle cerebella peduncles
what is the function of medulla oblongata?
most caudal segment- all tracts passing to or from spinal cord transverse the medulla- cranial nerves vi to xii are associated with medulla or pons medullary junction- medullary retiular formation contain cell gorups that influence heart rate & respiration also controls visceral functions
what is the anterior medulla characterised by?
characterized by an anterior median fissure, two laterally adjacent longitudinal ridges, the pyramids and the olive (inferior olivary eminence)
what is located inside the pyramids of medulla?
location of motor (pyramidal) decussation- 90% of corticospinal fibers cross the midline
what are the 2 parts of the olive of medulla?
superior olivary nucleus (auditory system- perception of sound)- inferior olivary nucleus (cerebellar motor learning & function)
what is the posterior medulla characterised by?
by gracile & cuneate fasciculi & their respective tubercles- tubercles are formed by underlying gracile & cuneate nuclei
what are the 3 nuclei in medulla oblongata?
autonomic nuclei (visceral activities), sensory & motor nuclei (of cranial nerves), relay stations (along sensory & motor pathways)
what are the relay stations of the medulla?
nucleus gracilis & nucleus cuneatus (relay somatic sensory info to thalamus), solitary nucleus (receives visceral sensory information), olivary nuclei (relay info regarding somatic motor commands)
what are the 4 classifications of cranial nerves?
sensory nerves (somatic sensory info e.g. touch, pressure), special sensory nerves (sensations e.g. smell, sight), motor nerves (axons of somatic motor neurons), mixed nerves (mixture of motor & sensory fibres)
what cranial nerves are sensory?
olfactory (i), optic (ii), vestibulocochlear (viii)
what cranial nerves are motor?
occulomotor (iii), trochlear (iv), abducens (vi), spinal accessory (xi), hypoglossal (xii)
what cranial nerves are both sensory & motor?
trigeminal (v), facial (vii), glossopharyngeal (ix), vagus (x)
where does cranial nerve i to iv originate from and function?
telencephalon (smell), retinal ganglion (vision), anterior aspect of midbrain (eyelid & eyeball movement), dorsal aspect of midbrain (innervates superior obligue + turns eye downward & laterally)
where does CN V originate from and function?
lateral part of pons at junction between pons & middle cerebellar peduncle - chewing, face & mouth touch & pain
where does CN VI originate from and function?
nuclei lying under floor of 4th ventricle & pons- turn eye laterally
where does CN VII originate from and function?
pons (cerebellopontine angle) above olive - controls most facial expressions, secretions of tears & saliva, taste
where does CN VIII originate from and function?
lateral to CN VII (cerebellopontine angle) - hearing & equilibrium sensation
where does CN IX originate from and function?
3 or 4 rootlets from groove between the olive & inferior cerebellar peduncle - taste & senses carotid blood pressure
where does CN X originate from and function?
8 to 10 rootlets from groove between olive & inferior cerebellar peduncle - senses aortic blood pressure, slows heart rate, stimulates digestive organs, taste
where does CN XI originate from and function?
spinal root: segments from c6 to c1 join & ascend up through foramen magnum- cranial root: 4 or 5 rootlets from lateral part of medulla- controls trapezius, SCM, swallowing movements
where does CN XII originate from and function?
10 to 15 rootlets from groove between olive & pyramid of medulla - controls tongue movements
what does the dorsal root ganglion contain?
collection of cell bodies of sensory neurons
where are motor neuron cell bodies?
in anterior & lateral horns of spinal cord gray matter - somatic in anterior horn & autonomic in lateral horm
what are 3 major somatic sensory pathways?
posterior column pathway (dorsal column/medial lemniscus), anterolateral pathway (spinothalamic), spinocerebellar pathway
what is the function of dorsal column/medial lemniscus?
carries sensations of highly localised (fine) discriminative touch, pressure, vibration & proprioception
what are the tracts if the dorsal column?
left & right fasciculus gracilis (carry sensation from inferior half below T6) & left and right fasciculus cuneatus (carry sensation from superior half of trunk t6 & above, upper limbs & neck)
where does the dorsal column synapse?
on 2nd order neurons of nucleus gracilis & nucleus cuneatus in medulla oblongata - then they cross over to opposite side of brains stem & enter medial lemniscus tract to synapse in ventral nuclei of thalamus
how does the ventral nuclei of thalamus sort info?
accoding to nature of stimulus & region of body involved - determines whether a given sensation is perceived as fine touch, pressure or vibration
what is the function of the anterolateral pathway?
provides conscious sensations of poorly localised (crude) touch, pressure & temperature
where does anterolateral pathway 1st order synapse?
synapse on 2nd order neurons within posterior (dorsal) gray horns- axons of interneurons cross to opposite of spinal cord before ascending with anterior or lateral spinothalamic tracts
what does the anterior spinothalamic tract carry?
crude touch & pressure sensations
what does the lateral spinothalamic tract carry?
pain & temp sensation
what are the descending corticospinal pathways?
corticonuclear tracts, lateral corticospinal tracts, anterior corticospinal tracts
what are the descending medial pathways?
vestibulospinal tract, tectospinal tract, resticulospinal tract
what are the descending lateral pathways?
rubrospinal tracts
what is the function of descending tracts?
conscious & subconscios commands
what is the somatomotor pathway?
cell body of UMN in motor cortex sends its axon to cell body of LMN in ventral horn of spinal cord then sends axon to skeletal muslce
what is the function of the cerebellum?
automatic processin centre, adjusts postural muscles, fine tunes conscious & subconscious movements, store motor plans - part of metencephalon
what seperates cerebellum from occipital lobe & pons?
tentorium cerebelli & from pon & midbrain by 4th ventricle
how is the cerebellum joined to the brainstem?
by 3 large paired bundles of fibres= superior cerebellar peduncles (to midbrain), middle cerebellar peduncles (to pons), inferior cerebellar peduncles (to medulla)
what are structures of the cerebellum?
folia, anterior & posterior lobes, cerebellar hemispheres, vermis, flocculonodular lobe
where is the folia?
surface of cerebellum - highly folded neural cortex
what seperates the anterior & posterior lobe?
by primary fissure
what seperates the cerebellar hemispheres?
at midline by vermis
what is the vermis?
narrow band of cortex
where is the flocculonodular lobe?
below 4th ventricle
what are disorders of cerebellum?
ataxia, dysmetria, decomposition of movement (fluidity is lost)
what is ataxia?
damage from trauma or stroke, intoxication, disturbs muscle coordination
what is dysmetria?
loss of ability to gauge distance, speed or power of movement- leads to overshooting or undershooting
what are the gray matter components of cerebellum?
cerebellar cortex & nuclei
what are the white matter components of cerebellum?
arbor vitae, cerebellar peduncles, transverse fibres
what are the types of axons in the cerebrum?
association, commissural, projection fibres
what are the association fibres in cerebrum?
connects with 1 hemisphere- arcuate fibres (1 gyrus to another) & longitudinal fasciculi (connect frontal lobe to other lobes)
what are the commissural fibres?
bands of fibres connecting 2 hemis e.g. corpus collosum & anterior commissure
what are projection fibres?
pass through diencephalon- links cerebral cortex with diencephalon, brain stem, cerebellum & spinal cord- internal capsure (all ascending & descending projection fibres)
what occurs if there is interruption to brain blood supply?
lasting seconds, can cause neurological symptoms- if lasting minutes, irreversible
what arteries supplies the brain?
internal carotid (forebrain) + vertebral (occipital, brain stem & cerebellum)
what does the internal cartoid arise from, form & give rise to?
arises from common carotid- forms carotid syphon- gives rise to hypophyseal arteries, opthalamic artery, anterior choroidal artery, posterior communicating artery
what does the middle cerebral artery supply?
lateral aspect of cerebral hemisphere
what do the vertebral arteries form?
basilar artery and give rise to branches that supply cerebellum and brain stem
what is the principal terminal branch of basilar artery?
posterior cerebral artery- supplies occipital lobe of cerebral hemisphere
what is the minimal blood flow for structure maintenance?
8-10 mL per 100g tissue/min
what is the minimal blood flow for continued function?
20 mL per 100g tissue/min- may have functional deficit in absence of death of tissue (infarction)
what is blood flow required for normal function?
750-1000mL/min
what is the cause of stroke?
ischemia (lack of blood flow) caused by blockage)- arterial embolism (interruption of blood flow to organ or body part due to an embolus)- hemorrhage (bleed)
what is the role of mammillary bodies?
process olfactory & controls reflex eating movements (contain motor nuclei)
what is the tuberal area?
located between infundibulum & mamillary bodies- controls pituitary gland function
what is the role of precentral gyrus?
primary motor cortex- contains motor cells bodies
what is role of postcentral gyrus?
primary sensory cortex
what seperates frontal & temporal lobe?
lateral fissure
what gryuses are contained in temporal lobe?
superior temporal, medial temporal, inferior temporal gyrus- superior contains primary auditory cortex
where is motor speech located?
Broca’s area in frontal lobe
what is the role of cingulate cortex?
process emotional content
what area of the skull takes longest to development?
anterior frontanelle (12-18 months to close) - point between frontal & parietal bone
what are the 4 subcortical nuclei?
caudate + putamen (striatum), globus pallidus, substantia nigra, subthalamic nucleus
what does the caudate nucleus end in?
amygdala
what is the lentiform nucleus?
combo of putamen & globus pallidus (both internal & external)
what are the parts of substantia nigra?
pars compacta (cells produce dopamine- dies in parkinsons) & pars reticulum
