The brain and cranial nerves Flashcards
Cerebrum
-weighs 1.3kg
-100 billion neurones
-outer layer= grey matter, accounts 80% weight
-inner= white matter
-vulnerable to injury through inter cranial pressure
-lobes of cerebrum correspond to bone names of skull
Cerebrum structure
-grey matter develops quicker than white matter causes cortical region to roll and fold in on itself
-ridges= gyri
-deepest ridges= fissures
-longitudinal fissure- divides R and L hemispheres
-central sulcus- divides frontal and parietal lobes
Frontal lobe
-largest lobe
-higher cognitive activity
-thinking, reasoning, understanding, language
-gives us our personality- auto biographical memory
-inhibited by alcohol and recreational drugs
Damage to frontal lobe
-increased display of combativeness
-abusive attitude
-inappropriate sexual activity
Areas of cerebral cortex
Brodmann’s areas -numbered regions of cortex that have been mapped to specific cognitive functions
Sensory areas- perception of sensory info
Motor areas- control execution of voluntary movements
Association areas- complex integrative functions eg. memory, personality, traits
Primary somatosensory area
-parietal lobe
-in postcentral gyrus
-receive nerve impulses for sensations of touch, pressure, vibration, temperature, pain
-impulse depends on number of neurones present not size of the body part
Parietal lobe
-supplied by large arteries
-where most strokes occur causing motor/ sensory paralysis
Sensory homunculus
describes the way the somatosensory area is distorted as the impulse is dependent on the number of neurones not the size of the body part
eg. larger region of the somatosensory area receives impulses from the lips/ fingers compared to the thorax/ hip- more receptors in lips
Motor area
-located in precentral gyrus of frontal lobe
-controls voluntary contractions of muscles
-homunculus map, more area devoted to muscles involved with skilled, complex or delicate movement
Location primary visual area
-located at posterior tip of occipital lobe
-mainly on medial surface
Primary gustatory area (taste) location
-located inferior to primary somatosensory areaP
Primary auditory area location
-superior part of the temporal lobe
Primary olfactory area location
-inferior medial temporal lobe
White matter in cerebrum
-consists primarily of myelinated axons in 3 types of tract:
1. association tracts- conduct impulses between gyri in the same hemisphere
2. commissural tracts- conduct impulses between gyri from one hemisphere to another
3. projection tracts- conduct impulses to lower parts of the CNS or vice versa
Corpus callosum
-one of the 3 important groups of commissural tracts
-thick band axons connects hemispheres
Basal nuclei
-part of grey matter
-conspicuous centres of cell bodies deep in cortex
-3 basal nuclei help initiate and terminate movements
-control subconscious contractions of skeletal muscles eg. swinging arms when walking
Limbic system
-3 integrated systems
-3 integrated systems
-1 and 2= limbic system
1.Reptilian brain- primary instincts and body functions, ANS
2.Mammalian brain- emotions, sexual desire, relationships, learning, memory
3.Cerebral cortex- neo cortex of homo sapiens
