Forebrain, third ventricle & related structures & cortex Flashcards
what are the major functional regions in the cerebral cortex?
-frontal lobe
-parietal lobe
-temporal lobe
-occipital lobe
what does the frontal lobe contain?
-motor cortex - controls voluntary mvt of the skeletal muscles
-prefrontal cortex - responsible for higher cognitive functions eg planning, decision making etc
what does the parietal lobe contain?
-somatosensory cortex - receives and processes sensory info from the skin, muscles and joints enabling the perception of touch, temp & pain
what does the temporal lobe contain?
-auditory cortex - processes auditory information
-wernickes area - language comprehension & understanding
what important functions does the occipital lobe have?
-contains the visual cortex - processes visual info from the eyes
-contains visual association areas
what are the 3 different types of fibres in the brain?
-association
-projection
-commisural
what are association fibres?
fibres which connect different areas within the same cerebral hemispheres
-eg the cingulum (white matter tract)
what are commissural fibres & give an example?
fibres that connect corresponding areas of the cerebral cortex in different hemispheres
eg the corpus callosum
what is a a projection fibre & give an example?
-fibres that connect the connect the cerebral cortex with lower brain regions such as the brain stem and spinal cord
eg the corticospinal tract
where is brocas area located & what is its function?
-located in the frontal lobe in the dominant hemisphere (which is typically the left hemisphere in RH individuals)
-associated with language production & speech articulation
what can happen as a result of damage to brocas area?
-brocas aphasia - difficulty in forming grammatically correct sentences
-patient is aware of the problem
-comprehension/ understanding of words is still intact
what wernicke’s area - where is it located, function?
-located in the temporal lobe
-situated in the dominant hemisphere
-interpret & comprehend spoken and written language
-processes incoming auditory info and assigns meaning to words & sentences
what can happen as a result of damage to wernickes area?
wernickes aphasia - fluent speech but impaired comprehension of language and difficulty in selecting appropriate words
-patient is not aware of the problem
what is the ventricular system in the brain?
- a set of communicating cavities within the brain
-these structures are responsible for production & removal of CSF
what are the ventricles of the brain?
-lateral ventricles
-third ventricle
-4th ventricle
describe the anatomy of the lateral ventricles
-right & left lateral ventricles
-they have horns - anterior and posterior horns
-body
how are the lateral ventricles connected to the third ventricle?
interventricular foramen (of Monro)
how is the third ventricle connected to the 4th ventricle?
via the cerebral aqueduct
what cells line the lateral ventricles?
ependymal cells which form a structure called the choroid plexus in the lateral ventricles which produces CSF
what structures allow the fluid to drain the CSF into the dural venous sinuses?
the arachnoid granulations
describe the flow of cerebral spinal fluid CSF through the ventricular system of the brain
-CSF is produced by the choroid plexus within the lateral ventricles
-from the lateral ventricles, CSF flows through the intraventricular foramen into the 3rd ventricle
-from the 3rd ventricle, CSF flows through the cerebral aqueduct into the 4th ventricle
-CSF flows from the 4th ventricle into the median aperture or the lateral apertures into the subarachnoid space
once the CSF goes into the subarachnoid space, where does it flow to next?
-CSF circulates within the subarachnoid space and is eventually reabsorbed into the blood stream via specialised arachnoid granulations which are located in the dural venous sinuses
what is hydrocephalus?
abnormal condition caused by build up/ accumulation of CSF in the ventricles of the brain
where is the 3rd ventricle located?
-midline of the brain, situated between the 2 halves of the thalamus
what structures are closely related to the 3rd ventricle?
-thalamus
-hypothalamus
-pineal gland / epithalamus
-optic chiasm
-infundibulum (stalk of pituitary gland)
what important hormone does the pineal gland secrete?
melatonin
what is the important function of the thalamus?
-it serves as a relay station for sensory signals travelling to the cerebral cortex
what are important parts of the thalamus located posteriorly?
-lateral geniculate body - visual info
-medial geniculate body - auditory relay
what are the major somatosensory pathways in the brain?
-dorsal column and spinothalamic tract
briefly describe the DCML pathway (dorsal column medial lemniscal pathway)
-sensations eg tactile, fine touch, vibration transmitted through this pathway
-3 orders of neurons
-1 neuron located in dorsal root ganglia
-2 order neurons located in the medulla
-3rd order neurons located in the thalamus
briefly describe the spinothalamic tract
-pathway carries sensations of pain, temp, pressure
-3 order neurons
-1 order - dorsal root ganglia
-2 order - dorsal horn of cord
-3rd order in thalamus
in terms of decussication, what is the difference between the DCML pathway vs spinothalamic tract?
-DCML - decussates in the medulla
-spinothalamic tract - decussates immediately
