Download TSM4 - Structure-Function Relationships

TSM4: STRUCTURE / FUNCTION RELATIONSHIPS IN THE NERVOUS SYSTEM
26/09/08
LEARNING OUTCOMES
Give an overview of the basic functions of the nervous system
LATERAL ASPECT OF THE BRAIN – CEREBRUM (FOREBRAIN)
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Looking at the lateral (outermost) surface of the brain, a deep cleft can be seen that crosses
superioposteriorly across the centre of the cerebrum called the lateral sulcus
The lateral sulcus is bisected by the central sulcus which descends from the great longitudinal fissure
at the top of the brain and terminates centrally at the lateral sulcus
Part of the parieto-occipital sulcus can be seen near the posterior border
Anterior to the central sulcus and inferior part of the lateral sulcus is the frontal lobe
Immediately posterior to the frontal lobe and superior to the lateral sulcus is the parietal lobe, whose
posterior border is roughly at the line of the parieto-occipital sulcus
Immediately posterior to the frontal lobe and inferior to the lateral sulcus is the temporal lobe with a
posterior border along the same line as the parietal lobe
Posterior to the parietal and temporal lobes is the occipital lobe, occupying the posterior-most section
of the cerebrum
MEDIAN SAGITTAL ASPECT OF THE BRAIN
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Inferior to the frontal and parietal lobes the corpus callosum can be seen which joins the two cerebral
hemispheres together
Running anteriorly across the occipital lobe from the posterior margin to the parieto-occipital sulcus is
the calcarine sulcus
Inferior to the corpus callosum is the thalamus, hypothalamus and pituitary respectively
The pituitary stalk descends from the hypothalamus at the superior border of the temporal lobe
At the level of the pituitary stalk is an anterior projection called the optic chiasm
Inferior to the hypothalamus along the midline are the mammillary bodies
The midbrain occupies a small area inferior and posterior to the thalamus with two posterior
projections, the superior and inferior colliculi
BLOOD SUPPLY
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The arterial supply to the brain is from two pairs of arteries: the vertebrals and internal carotids
o These arteries divide and form a dense arterial network on the ventral brain surface
o Three main paired branches that supply the cerebrum are the anterior, posterior and middle
cerebral arteries
o The middle cerebral artery is the most important and is often involved in strokes
The primary motor cortex has lateral and medial elements anterior to the central sulcus supplied by
the middle and anterior cerebral arteries respectively
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The primary somatosensory cortex has lateral and medial elements posterior to the central sulcus
which are similarly supplied by the middle and anterior cerebral arteries respectively
o The lateral regions of the above are responsible for areas above the waist
o The medial region of the above are responsible for areas below the waist
Froca’s area (motor language) is superior to the lateral sulcus on the anterior side and is supplied by
the middle cerebral artery
Wernicke’s area (‘sensory language’) is inferior to the lateral sulcus on the posterior side and is also
supplied by the middle cerebral artery
The primary visual cortex at the posterior border of the medial surface is supplied by the posterior
cerebral artery