Nervous system overview II Flashcards
hindbrain: consists of
- pons
- cerebellum
- medulla oblongata
metencephalon: general features
- aka cerebellum
- 10% of volume of entire brain
- 80% of neurons in brain
- ‘silent area’ direct electrical stimulation causes no sensation and few motor outputs
metencephalon: function
- controls balance and posture (from inputs from vestibular system, proprioceptors)
- coordinates timing and force of muscles groups during voluntary movements
- ‘guidance system’ error detector to continuous refine motor output during task
- helps in motor learning
- controls eye movements: part of verstibulooocular reflex (VOR)
eg. lack of cerebellum
- 9 cases recorded, most patients die young
- CT scan showed lack of cerebellum
- dizziness, nausea, moderate motor impairment (walking) and mild speech problems (delayed speech development)
- cerebellar functions may have been taken over by cortex
brainstem: name areas
- medulla oblongata
- pons
- midbrain
brainstem: function
controls numerous essential functions:
- heart rate
- breathing
- sleeping
- eating
- consciousness/ alertness
brainstem: primary motor/ sensory innervation of face and neck
- via cranial nerves
- 10 arise from the brainstem
metencephalon: function
- aka pons
- relays signals from forebrain to cerebellum
- nuclei for efferent fibres CN V - VIII
metencephalon: nuclei deal primarily with
- sleep, bladder control respiration
- hearing, equilibrium, posture, eye movements
- taste, swallowing, fascial expressions, facial sensation
metencephalon: pontine respiratory centres and name centres
- essential for regulation of respiration
- modulate respiratory nuclei in medulla
- pneumotaxic centre
- apneustic centre
metencephalon: pneumotaxic centre
- controls rate of breathing through rhythmic bursts of activity
metencephalon: apneustic centre
- controls depth of breathing
- works w pneumotaxic centre to ensure ventilation is smooth and coordinated
myelencephalon: general function
- aka medulla oblongata
- controls many autonomic functions essential for life
- eg. cardiovascular and respiratory systems
- rhythmic cycle of breathing originates in medulla
myelencephalon: breathing- chemoreceptors
- medulla
- monitor blood pressure, CO2, pH
myelencephalon: breathing- dorsal respiratory group (DRG)
- medulla
- inhalation
- control rhythm of breathing (pacemaker cells)
- send impulses to motor nerves innervating diaphragm and intercostal mm
myelencephalon: breathing- ventral respiratory group (VRG)
- medulla
- inhalation and exhalation
- sends impulses to motor nerves innervating throat, diaphragm, intercostal and ab mm
myelencephalon: breathing- DRG/ VRG activity modified by
- medulla
respiratory centres in the pons
myelencephalon: nuclei for
- medulla
- efferent fibres CN VIII - XII
myelencephalon: assists in control of muscle tone, balance, posture
- medulla
- vestibula nuclei (rostral medualla) - caudal pons
- receive inputs regarding balance and spatial orientation from cerebellum and vestibular apparatus in inner ear (via CN VIII)
- sends signals to motor neurons controlling leg mm, and muscles of head, eyes, neck, trunk, proximal limbs
mesencephalon: tectum features
- midbrain
- superior colliculi
- inferior colliculi
mesencephalon: tectum superior colliculi (SC)
- receive visual input from thalamus (lateral geniculate nucleus)
- coordinates eye movements
- orientation of eyes and head
mesencephalon: tectum inferior colliculi (IC)
- receive auditory input from thalamus (medial geniculate nucleus)
- auditory signal integration
- frequency recognition
- pitch discrimination
SC + IC =
corpora quadrigemina
mesencephalon: tegmentum name parts
- midbrain tegmentum
- pontine tegmentum
- medullary tegmentum
mesencephalon: tegmentum- midbrain tegmentum general features
- red nucleus
- substantia nigra
- ventral tegmental area
- periaqueductal grey matter
- nuclei of CN III and IV
mesencephalon: tegmentum- midbrain tegmentum red nucleus
- motor coordination of shoulders/ upper arms
mesencephalon: tegmentum- midbrain tegmentum substantia nigra
- movement planning
- eye movements
- reward seeking
- addiction
mesencephalon: tegmentum- midbrain tegmentum ventral tegmental area
- dopaminergic neurons
- reward
- pleasure
mesencephalon: tegmentum- midbrain tegmentum periaqueductal grey matter
- controls basic movement sequences involved in fighting, mating, descending pain modulation
mesencephalon: tegmentum- pontine tegmentum
nuclei of CN V to VIII
mesencephalon: tegmentum- medullary tegmentum
nuclei of CN IX, X, XII
mesencephalon: tegmentum- what is the reticular formation
- network of ‘reticular nuclei’ on each side of tegmentum (midbrain, pons, medulla)
- part of reticular activating system (RAS) or ascending around system
- critical for maintaining ‘alert wakefulness; and controlling sleep-wake transitions
- helps to promotes cortical ‘alertness’ and direct attention to specific events
mesencephalon: tegmentum- reticular formation receives input from
- cerebral cortex, cerebellum, vestibular nuclei, ascending (sensory) fibres of spinal cord
mesencephalon: tegmentum- reticular formation projects to and importance
- thalamus
- hypothalamus (diencephalon)
- telencephalon
- making areas more receptive to signals comings from other pathways
cranial nerves: features
- 12 cranial nerves (CN) give sensory and motor function to head and neck
- some involved in autonomic control (eg. vagus CN X)
- 10 arise from nuclei in midbrain and hindbrain (pons and medulla)
cranial nerves: mnemonic
oh oh oh, to touch and feel very good velvet, ah heaven
diencephalon: name main structures
- thalamus
- hypothalamus
- epithalamus
diencephalon: function
- integrates sensory info and motor commands
- regulates autonomic functions, emotions
thalamus: features
- midline, symmetrical structure
- comprises multiple nuclei
thalamus: function
- relays all sensory (afferent) input to cortex (exc olfaction)
- regulate consciousness, sleep, alertness
- relays info from cerebellum and basal ganglia -> motor cortex to coordinate movement
thalamic nuclei: name 3 groups
- relay nuclei
- association nuclei
- ‘nonspecific’ nuclei
thalamic nuclei: relay nuclei function
process signals coming from: - periphery (sensory afferents), - basal ganglia, - cerebellum (motor pathways) and relays to cortex
thalamic nuclei: relay nuclei eg
relay: ventral nuclei, medial/ lateral geniculate nuclei
thalamic nuclei: association nuclei
connect areas of cortex w each other
- eg. control eye movements and attending to visual stimuli
- connect limbic areas involved in emotions and autonomic regulation
thalamic nuclei: association nuclei eg.
association: pulvinar, dorsal nuclei
thalamic nuclei: nonspecific nuclei
receive input from other thalamic nuclei, cortex and brainstem
- influence arousal, alertness and sleep (ARAS)
thalamic nuclei: nonspecific nuclei eg.
nonspecific: reticular nucleus
hypothalamus: function
- responds to int/ext environmental changes detected by somatic sensory/ visceral sensory fibres
- important component of limbic system (esp generating visceral response to emotional stimuli)