lect 14,15,16, 17: neuroanatomy & neurophysiology Flashcards
7.1 describe the structural organization of the CNS
- includes brain and spinal cord
subdivision:
cerebral hemispheres
diencephalon: thalamus, hypothalamus, epithalamus
brainstem: midbrain, pons, medulla, cerebellum
7.1.1 define gray matter, white matter, nucleus, ganglion
gray matter: non-myelinated, dendrites, nuclei: intense inter/synaptic communication
white matter: has been myelinated, axons with myelinated sheets around them
7.1.1 define gray matter, white matter, nuclei (spinal cord)
spinal cord: butterfly shape central cavity with grey matter, white matter outside
7.1.1 define gray matter (cerebral cortex)
define: type of thought, contralateral, lateralization
- conscious thoughts
3 functional areas: motor, sensory, association
contralateral: each hemisphere handles sensory and motor functions of opposite side of body
lateralization: largely symmetrical but not 100% equal in function
no functional area acts alone, all conscious behaviour involves entire cortex
7.1.2 describe the lobes, gyri and sulci of cerebral hemisphere
- gyrus: hill
- sulcus: valley, anatomical land marks
longitudinal fissure: (left and right)
transverse fissure: (cerebrum and cerebellum)
- lobes: frontal, parietal, occipital, temporal, insular, central sulcus: pre central/postcentral gyrus, parieto-occipital sulcus, lateral sulcus
7.1.2.1 location and function of motor areas
location: posterior part of frontal lobes, primary motor cortex, premotor cortex, Broca’s area and frontal eye field
7.1.2.1 location and function of motor areas: PRIMARY MOTOR CORTEX
(BA 4): pre central gyrus of frontal lobe of each hemisphere
- contains pyramidal cells (large neutrons) allow control of skeletal muscles
- body represented spatially = somatotopy
- digits require precise motor control
- motor innervation is contralateral
- no overlap between muscles involved unrelated movements
- stroke: damage to area of right hemisphere paralyzes body muscles of left, only voluntary movement lost, reflex contraction still possible
7.1.2.1 location and function of motor areas: PREMOTOR CORTEX
- anterior to primary motor cortex
- helps plan movements (basic motor movements into complex tasks)
- coordinates movements of multiple muscle groups simulataneousy (referred to as muscle memory)
- can control voluntary actions that depend on sensory feedback (feeling for something in the dark)
damage to premotor cortex: can have some movement but do not know where to put them
7.1.2.1 location and function of motor areas: Broca’s area + Frontal eye field
Broca’s area:
- region of BA 44
- present in one hemisphere only (usually left)
- originally thought to be ONLYYY a motor speech area
- prepares when we are about to yap/ organize sounds into words
Frontal eye field:
- close to BA 8
- controls voluntary eye movement
7.1.2.1 location and function of sensory areas (PSC + SAC)
primary somatosensory cortex (PSC):
- in postcentral gyrus of parietal lobe (BA 1-3)
- receives info from somatic sensory receptors (skin)
- & info from proprioceptors (joints + muscles –> spatial discrimination)
somatosensory association cortex:
- posterior to PSC (BA 5-7)
- integrate + analyze somatic inputs ( temp + pressure)
- interpret size, texture, relationship of parts based on prior experience (feeling for something in your pocket)
7.1.2.1 location and function of association areas (VISUAL)
primary visual cortex: map of visual space on retina
visual association area: surround PVC, interprets visual image based on prior experience (recognize face, ) + movement (see if something is moving or stationary)
damage to this area: blindness, some visuality but cannot understand what we’re seeing
visual agnosia: inability to understand what you’re seeing
7.1.2.1 location and function of association areas (AUDITORY, VESTIBULAR)
primary auditory cortex: sound for pitch, rhythm, loudness
auditory association area: interpretation based on memory (speech, words, music)
vestibular (equilibrium) cortex:
- not visible at surface, deep in lateral sulcus, posterior to insular, adjacent to parietal cortex
- awareness of balance
7.1.2.1 location and function of association areas (OTHERS)
olfactory:
- medial temporal lobes = uncus
- small in humans, tissue forms limbic system,(emotions/memory)
- conscious awareness of different odours
gustatory:
- insula
- aware of diff tastes
visceral sensory cortex:
- posterior to gustatory cortex
- conscious perception of visceral senses: (upset stomach, full bladder)
7.1.2.1 Multimodal association area
- receives input and sends output from multiple different areas
sensory receptor –> primary sensory cortex –> sensory association cortex –> multimodal association area
example
1. anterior association area (prefrontal cortex):
most complicated cortical area, intellect, complex learning, recall, personality (working memory)
- abstract areas, judgment, reasoning, concern
- matures slowly: depends on feedback from social environment
- closely linked to limbic system: involved in mood
- posterior association area (temporal, occipital, parietal lobes):
- stores complex memories
- linked to sensor input (feel/see)
- localization of self and surroundings in space
contralateral neglect: recognize one part of body and not the other
- recognize patterns, faces
- understanding language (written + spoken - wernicke’s area) - limbic association area
- emotional impact (aware of danger in a situation based on prior learning/experience)
7.1.2.2. Explain hemispheric lateralization
(commissural, associating, projection fibres)
- each hemisphere has abilities not completely shared by other hemisphere
- cerebral dominance: hemisphere that is dominant for language
- 90% of people: left hemisphere dominant for math, logic, language e
- right hemisphere: creativity, visual-spatial skills, intuition, emotion, artistic, musical skills
- left cerebral dominance: right handed
- right cerebral dominance: left handed/ambidextrous
- communicate with each other b/w cortex & lower CNS centres
commissural fibers: connect corresponding areas b/w 2 hemispheres, largest is corpus callosum,
associating fibers: connections within hemisphere w gyrus + lobes, diff parts of same hemisphere
projection fibers: to or from cortex and rest of nervous system, run vertically (lower brain)
7.1.2.3. Describe the locations of the basal nuclei and the limbic system
- caudate nucleus, putamen and globus pallidus
- inputs from entire cerebral cortex + other subcortical nuclei
- no direct access to motor pathways: project to premotor + prefrontal cortices to influence muscle movement directed by primary motor cortex
- precise roles elusive ( difficult to access, some overlap with cerebellum)
- start/stop/monitor intense movements (arm swing)
- inhibit antagonistic/unnecessary actions by only sending best response to cortex
- associated with cognition and emotion (filter)
7.1.2.3. Describe the locations of the basal nuclei and the limbic system (DISEASE)
Huntington - too much movement
- Huntington protein increases, degenerates nuclei, connections to frontal lobe lost, unable to control feeling/thought/movement
Parkinson’s- too little movement
- degeneration of dopamine releasing neuron’s of substantia nigra (mid brain)
- overactivity, tremors, loss of facial expression, difficulty walking/writing
7.1.2.4. Describe the structural components of the diencephalon (thalamus)
thalamus, hypothalamus, epithalamus: enclose 3rd ventral
- thalamus:
- INFO RELAY STATION, GATEWAY TO CEREBRAL CORTEX
- 2 masses of grey matter held by midline (inter thalamic adhesion)
- different nuclei named after position (lateral, medial etc)
- afferent impulses from all senses and of body converge here, gateway to cerebral cortex
- sorts & edits info, direct impulses to region of cortex
- crude recognition of senses as pleasant or unpleasant
- inputs emotion and visceral function from hypothalamus
- mediating senses, arousal, learning, memory
7.1.2.4. Describe the structural components of the diencephalon (hypothalamus - 7 functions )
hypothalamus:
- below thalamus
- autonomic control centre: bp, heart, respiration,
- emotion response: heart of limbic system
- body temp regulation
- food intake regulation: hunger, satiety (satisfied)
- water balance regulation: release ADH, thirst centre
- sleep-awake cycle
regulation: suprachiasmatic nucleus (biological clock) - control of endocrine system: release supraoptic and paraventricular nuclei which produce hormones, ADH and oxytocin
hypothalamic disturbances:
disorders in body homeostasis: obesity, sleep, emotion imbalance, dehydration
7.1.2.4. Describe the structural components of the diencephalon (epithalamus)
epithalamus:
- dorsal part, forms roof of 3rd ventricle
- pineal gland extends from dorsal border (secrete melatonin)
- also has choroid plexus (CSF forming structure)
7.1.2.5. Describe the structural components of the brainstem
(midbrain)
- midbrain:
- 2 cerebral peduncles carry large motor tracts (motor response)
- hollow cerebral aqueduct runs through midbrain
-periaqueductral gray matter: for pain suppression
- corpora quadrigemina (4 paired twin bodies)
- superior colliculi: visual reflex, follow moving object
- inferior colliculi: auditory relay, startle reflex
midbrain slice:
- level of cerebral aqueduct
- substantia nigra: high melanin content (communicate via dopamine as neurotransmitter), degeneration of this leads to parkinsons
red nuclei: rich vascular supply, have iron pigment, relay pathways for outgoing pathways and limb flexion, some associated with reticular formation
7.1.2.5. Describe the structural components of the brainstem
(pons)
pons: 4th ventricle level
- bridge, connection tracts
- cranial nerve V (trigeminal), VI (abducens), VII (facial)
7.1.2.5. Describe the structural components of the brainstem
(medulla oblongata)
medulla oblongata:
- pons to spinal cord
- pyramids (large motor tracts) decussation of which: crossing neural information
- olivary nuclei: relay sensory info re muscles and joints to cerebellum
- cranial nerves: XII hypoglossal, IX glossopharyngeal, X vagus
- *vestibulochoclear nerve fibers (VIII) for auditory and balance relay
- corresponding hypothalamus centres. hypothalamus CONTROLS through sending info through centres in medulla:
- cardiovascular
- respiratory
- vomit, hiccup, swallow, cough, sneeze