Localisation Flashcards
What do the cerebral hemispheres consist of?
Include a dense core of white matter with an overlying thin layer of grey matter (cortex)
Describe the cerebral cortex
- Varies in thickness from 2-4mm
- Heavily folded to increase surface area (over half the total surface area is hidden by the walls of the sulci)
- Laminar arrangement (I-IV)
- 6 layers with specific cells
- Specific sulci are used to divide the cerebral hemispheres into lobes and specific gyri
What does the central sulcus divide? What is found on either side of the central sulcus?
- Divides the frontal lobe from the parietal lobes
- Precentral gyrus in front
- Postcentral gyrus behind
Sulci and gyri view
Which sulci and gyri are found on the lateral aspect of the frontal lobe?
2 sulci:
- Superior
- Inferior
Therefore 3 gyri:
- Superior
- Middle
- Inferior
What does the lateral sulcus separate?
Separates the frontal and parietal lobes from the temporal lobe
Which sulci and gyri are found on the lateral aspect of the temporal lobe?
2 sulci:
- Superior
- Inferior
Therefore 3 gyri:
- Superior
- Middle
- Inferior
What does the parieto-occipital sulcus separate?
The parietal lobe from the occipital lobe
Where is the calcarine sulcus found?
located on the medial surface of the occipital lobe
Which sulcus runs parallel with the corpus callosum?
The cingulate sulcus
What does the cingulate sulcus separate?
Separates the frontal and parietal lobes from the cingulate gyrus
In which view of the brain is the cingulate sulcus seen?
Only in the medial view
Where is the collateral sulcus found?
On the medial surface of the temporal lobe
What does the collateral sulcus define?
Defines the position of the parahippocampal gyrus
What is the uncus?
- an anterior extremity of the parahippocampal gyrus
- the most medial part of the temporal lobe
What is the parahippocampal gyrus? What lobe is it part of?
A cortical region in the medial temporal lobe that surrounds the hippocampus
Sulci and gyri: medial vs lateral view
What is the limbic system?
- A set of brain structures located on both sides of the thalamus
- Formed mainly of the subcallosal gyrus, the cingulate gyrus, the parahippocampal gyrus, and the hippocampus.
- Deal with emotion and memory
What part of the brain is circled in red?
Diencephalon
What is an uncal herniation? What is compressed?
- Occurs due to rising intracranial pressure
- Uncal parts of temporal lobe herniate below the tentorium cerebelli
- Compresses midbrain
What is a tonsillar herniation? What does it compress?
- Cerebellar tonsils herniate through the foramen magnum
- This compresses the medulla
Lobes medial and lateral
What is a ‘Broddman area’?
- A region of the cerebral cortex
- 46 areas in total
- Based on cellular organisation of cerebral cortex
- Specific areas of cortex are believed to carry out specific functions
- (you don’t have to remember numbers)
There are primary projection areas in the brain.
- What occurs at the primary sensory areas?
- What occurs at the primary motor areas?
- Sensory: specific sensory pathways terminate here –> perceived sensation
- Motor: specific motor pathways originate here
The primary sensory areas have different modalities. What cortical area is associated with each modality:
- General sensation (somaesthetic)
- Visual
- Auditory
- Olfactory
- Gustatory
- Post-central gyrus
- Either side of calcarine sulcus (striate cortex) and occipital pole
- Heschl’s gyrus (superior temporal gyrus)
- Uncus
- Inferior post-central gyrus
Which cortical area is the primary motor cortex?
Pre-central gyrus
Medial and lateral view of primary motor and sensory areas
What are secondary association areas?
Lie near the primary projection areas and are associated with further processing
What is the function of 2ary sensory areas?
- Receive input from 1ary sensory areas
- Involved in interpretation/understanding
- 1ary areas perceive info
- 2ary areas interpret info (give it meaning)
What is the function of the 2ary motor areas?
- Sends output to 1ary motor area
- Organises patterns of movement
- Organises instruction and then sends to 1ary area
- 1ary area then sends command to move that body part
The secondary sensory areas have different modalities. Which cortical area is associated with:
- General sensation (somaesthetic)?
- Visual?
- Auditory?
- Superior parietal lobe
- Pre-striate area
- Lateral fissure/superior temporal gyri
The 2ary motor areas have different modalities. What cortical area is associated with:
- Premotor area?
- Supplementary motor area?
- Frontal eye field?
- Anterior to precentral sulcus on lateral surface
- Anterior to precentral sulcus on medial surface
- Anterior to premotor
What is function of primary motor cortex in pre-central gryus?
- Sends descending motor fibres through brainstem, through spinal cord via specific tracts to perform muscle contractions
- Controls voluntary contraction of specific muscles
- Somatotopically organised
Where are the associated motor areas located?
Anterior to primary motor cortex
What are the association motor areas?
- Supplementary motor (sm)
- Pre-motor (pm)
- Frontal eye field (8)
- Broca’s area (44, 45)
Where are the supplementary motor and pre-motor association areas located? What is their function?
- Located anteriorly to primary motor cortex (pre-central gyrus)
- Sm located more medially
- Pm located more laterally
- Function: learned complex motor activities and storage of those activities
- Organise instructions to perform a complex motor activity and send it to the pre-central gyrus to execute this movement
- E.g. learning to tie shoelaces
- Storage of those activities (so can perform activity again)
- Organise instructions to perform a complex motor activity and send it to the pre-central gyrus to execute this movement