Cortex and Blood Supply

Localisation of function of the brain

Idea that different functions are localised to a specific lobe in the cortex of the brain

Frontal lobe

Higher cognitive functions - decision making, consciousness, problem solving, emotions, behaviour, personality, intelligence
Broca’s area - speech production (only present in left hemisphere)

Parietal lobe

Integrating body’s sensory information, body perception, integrate somatosensory information, coordination of senses in relation to the environment

Temporal lobe

Parts of memory, hearing, emotion, some aspects of language, hearing, auditory cortex
Wernicke’s area - language processing/understanding (only in left hemisphere)

Occipital lobe

Visual processing, object and face recognition. assessing depth and distance, mapping visual world

Sensory homunculus

Description of how each body part is mapped to a specific area of the cerebral cortex in the primary somatosensory area (post central gyrus is parietal lobe)

Blood supply of the brain

Blood enters cranial cavity through two pairs of arteries
Internal carotid arteries anteriorly and the vertebral arteries posteriorly
Vertebral come to form the Basilar artery
These anastomose at the base of the brain as the Circle of Willis

Circle of Willis

Blood supply of cerebral cortex

Yellow by anterior cerebral
Red by middle cerebral
Blue by posterior cerebral

How impaired blood supply affects function

Reduced O2 to area means nerve tissue will die
Brain has high metabolic rate so requires high O2

Stroke

Blockage of blood supply to the brain
When brain is starved of oxygen

Brisk reflex

Reduced descending inhibition of reflex

Reduced sensation

Sensory pathways damaged

Weakness

Damage to motor pathways

Speech deficits

Damage to Broca’s area

Altered muscle tone

Damage to reticulospinal tract