Neuroanatomy Flashcards
What are sulci and gyri?
Sulci are the valleys formed by the folding of the cerebrums lobar surface.
Gyri are the ridges formed.
Primary (major) sulci do not change in their appearance
Secondary (minor sulci) may vary
Where are the primary motor cortex and primary somatosensory cortex located in the brain?
Primary Motor Cortex is located on the precentral gyrus (i.e the ridge of the frontal lobe that forms the central sulcus)
Primary somatosensory cortex is located on the postcentral gyrus (i.e. the ridge of the parietal lobe that forms the central sulcus)
What is the name given to the distribution of body parts in the primary motor and somatosensory cortices?
Homunculus representation
Regarding the lateral sulcus:
a) What is sometimes referred as?
b) Which lobes does it separate?
c) What structure is located within it
a) The lateral sulcus is also referred as the sylvian fissure
b) The lateral sulcus separates the frontal and temporal lobes
c) Deep within the lateral sulcus is the insula. The insula is the primary gustatory cortex
Which structures define the middle frontal gyrus?
The middle frontal gyrus is located between the superior frontal sulcus and the inferior frontal sulcus.
The middle frontal gyrus forms the dorsolateral prefrontal cortex - largely responsible for executive functions of the human brain
Outline the major primary sulci and the functions associated to the with the following key brain regions
- Dorsolateral prefrontal cortex
- Cingulate gyrus
- Orbitofrontal cortex
- Primary auditory cortex
- Inferior parietal lobe
- Primary striate cortex
- Superior frontal sulci and inferior frontal sulci. Form middle frontal gyrus that makes dorsolateral prefrontal cortex. Executive function occurs here
- Cingulate gyrus formed from cingulate sulcus on the medial side of frontal lobe. Motivation is the function here.
- On the inferior side of frontal lobe the olfactory sulcus and orbital sulcus are located. This is around the orbitofrontal cortex where associative learning and decision-making takes place.
- Superior temporal sulcus forms the superior temporal gyrus (on the top of the temporal lobe inferior to the lateral sulci). The primary auditory cortex is located here.
- The inferior parietal lobe is formed from the interparietal sulcus (separates parietal into superior and inferior lobes). Inferior paritetal lobe itself is formed from angular gyrus and supramarginal gyrus. The function is visuospatial attention.
- The primary striate (visual cortex) is located in the medial occipital cortex. The calcarine sulcus forms this.
How can we identify the dominant hemisphere?
The hemisphere contralateral lateral to the dominant hand but not always!
The dominant hemisphere mediates language and speech functions
What scales can be used to dominance?
Annette’s handedness scale
Edinburgh handedness inventory
Note these scales better assess dominance as handedness does not always correlate to dominance. 10% of right handed individuals the right hemisphere is dominant (mostly contralateral). However for L handed individuals 64% the L hemisphere is dominant (ipsilateral). 20% have R hemisphere dominance and 20% have bilateral dominance,
What is the planum temporale?
It is a triangular region on the superior temporal gyrus (note primary auditory cortex) important for language processing.
It is known to be very asymmetric with larger size on L > R hemisphere (in 65% of individuals).
In schizophrenia this asymmetry may be reduced or reversed.
Outline some functional deficits that can occur with L or R or bilateral lesions?
L hemisphere:
- Aphasia
- Right-left disorientation
- Finger agnosia (inability to name, move or identify fingers instructed by examiner)
- Dysgraphia (aphasic)
- Dyscalculia (number alexia)
- Limb apraxia
R hemisphere:
- Visuospatial deficits
- Anosognosia
- Neglect
- Dysgraphia (spatial, neglect)
- Dyscalculia (spatial)
- Constructional apraxia, dressing apraxia
Bilateral: face recognition
Higher level functions usually lateralise to one hemisphere.
Fundamental brain functions are bilateral)
Name some neuroscientist that originally defined the limbic system and what constitutes the Papez circuit?
Papez, Maclean and Broca
Papez circuit:
- Hippocampus -> fornix –> mamillary bodies -> mamilthalamic nucleus -> genu of internal capsule -> cingulate gyrus -> parahippocampal gyrus -> preforant pathway -> back to hippocampus
Regions later added to limbic system:
- Orbitofrontal cortex
- Amygdala
- Septum
- Basal forebrain
- Nucleus accumbens
Name some functions of the limbic system
- Emotional processing
- Coordination of neuroendocrine response (via hypothalamus)
- Coordination of reward processing via nucleus accumbens
Outline the medial temporal structures?
- Hippocampus
- Amygdala
- Enterohinal cortex
- Parahippocampal cortex
Outline the functions of the basal ganglia
- Coordinating movement
- Turning abstract thought into a voluntary response
They are a group of grey matter nuclei that form the largest subcortical structure in the brain
What structures make up the basal ganglia?
- Striatum (caudate nucleus + putamen)
- Pallidum (globus pallidum)
Putamen + Globus Pallidum = Lentiform/Lenticular nucleus
Although the subthalamic nuclei and substantia nigra functionally relate to the basal ganglia they are not structurally included
What parts of the brain are supplied by the:
- Anterior cerebral
- Middle cerebral
- Posterior cerebral
- Anterior cerebral –> medial and superior strips of lateral cerebral cortex (up to parietal/occipital border)
- Middle cerebral –> lateral aspect of cerebral hemisphere’s including Wernicke’s and Broca’s
- Posterior cerebral artery (basillar) –> inferomedial temporal lobe and occipital lobe
- Pons is supplied by basilar artery
- Medulla is supplied by posterior inferior cerebellar arteries and anterior spinal branches of vertebral arteries
