Unit 14: The brain and the basal ganglia Flashcards
What anatomical components are important in the lateral sulcus of the brain?
Superior sinus of the temporal lobe - auditory cortex
Deep to the lateral sulcus - the insula - gustatory and sensorimotor functioning.
What seperates the parietal and the occpital lobe?
The parieto-occipital sulcus
What sulcus is important for identifying the primary visual cortex?
Calcarine sulcus
What meningeal structure seperates the left and right cerebellum?
The falx cerebelli
What are the different ways the cerebellum can be separated?
Left and right by vermis (superior and inferior part)
The primary fissure - divided into the anterior and posterior lobe
The horizontal lobe - divided posterior into the inferior and superior lobe
What structure can be found on the inferior surface of the cerebellum?
The tonsil (note can be displaced through foramen magnum)
What structures are found on the ventral surface of the cerebellum? (Aka facing the brainstem)
The nodule - continuation of the inferior vermis
The flocculus
Together form the flocculonodular lobe (functional lobe)
What is the cerebellar folia?
Appearance of cerebellum - leaf-like.
Grey matter around outside and also in channels within, surrounded by white matter which extends within as channels (tree branches)
Describe the location of the cerebellar arteries in relation to the basilar artery
Superior cerebellar - branch from basilar before becomes posterior cerebral
Anterior infer - just before basilar runs over pons
Posterior inferior - just before unification of vertebral to form basilar
What do the different cerebellar arteries supply?
Superior - superior portion of anterior lobe
Ant inf - flocculus, sup posterior lobe, and potentially inferior posterior lobe
Post inf - inferior vermis and inferior position of the posterior lobe.
What is the basic function of the cerebellum?
Involved in motor control on the unconscious level.
Mainly influences action of the ipsilateral side
What is the vestibulocerebellum and what is its function?
Flocculonodular lobe/vermis
1. balance and control
2 posture
3. Gaze control
What is the spinocerebellum and what is its function?
Made from the vermis, paravermis and the anterior lobe
1. posture
2. Monotr and correct motor activity
3. coordination
What is the cerebrocerebellum and what is its function?
The lateral hemispheres
1. coordination
2, motor learning
3. Initiation of movement
What are the three different functional division of the cerebellum?
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellar
What are the signs and functions of cerebellar dysfunction?
DANISH
Dysdiochokinesia - inability to perform rapid alternating movements
Ataxia - coordination
Nystagum - r,r,i eye
Intention tremor
Slurred speech
Hypotonia
What structures are associated with the ventricles?
The caudate nucleus
The thalamus
Where is CSF producted?
Choroid plexus - invagination of vascular pia matter into roof of lateral 3rd and 4th ventricles
What is the diaphragm sella?
Forms a dural roof over the pituitary gland
Where is the cavernous sinus located?
What does it drain into?
Bilateral plexus of drain
Found lateral to the sella turcia
Drains into the sigmoidal sinus via the superior petrosal sinus
Or into the internal jugular vein via the inferior petrosal sinus
What is the great cerebral vein?
What is its function?
Deep vein of the cerebrum
Other deep veins drain into it.
In combines with the inferior sagittal sinus to drain into the straight sinus.
What are the tributaries for the greater cerebral vein?
The internal cerebral veins (Left and right) - thalamus and choroid plexus of 3rd and lateral ventricles
Basal veins - midbrain structures.
These are the deep cerebral veins.
How can the superficial cerebral veins be classified?
Superior cerebral vein
Superficial middle cerebral vein
Both are present on the left and the right.
What is the role of the superior cerebral vein?
Travels superiorly up the lateral brain to drain into the superior sagittal sinus
What is the drainage route of the superficial cerebral vein?
Travels along the lateral fissure
1. Drain into superior sagittal sinus via a superior anastomotic vein
2. Drains into the transverse sinus via an inferior anastomotic vein
3. Extends internally into the cavernous sinus.
How do the basal ganglia affect movement?
Indirectly via regulating the activity of the thalamus and the primary motor cortex.
Via a balance of activity between the indirect and direct pathway.
What is the direct pathway of the basal ganglia?
The cerebral cortex and have glumatinergic projections to activate the striatum.
The striatum has GABAerigc projections to inhibit the GP internal and the SN pars reticulata.
Therefore reducing inhibitory GABAerigc projections from the GP internal and the SN pars reticulata to the thalamus
This enables the thalamus to communicate with M1 to initiate movement.
What is the indirect pathway of the basal ganglia?
- The cerebral cortex has glutaminergic projections to activate the subthalamic nucleus
- The cerebral cortex glutaminergic projections active the straitum, which has GABAerig projections into the GP external, this reduced GABAerig inhibition of the subthalamic nucleus via the GP external
The activate subthalamic nucleus has glutaminergic projections to the GP internal and SN pars reticularis.
These have GABAergic projections to inhibit the thalamus, prevent communication with M1, this inhibits unwanted movements.
How does the substania nigra pars compacta modulate the indirect pathway of basal ganglia?
Has dopaminergic projections to inhibit the striatum
This results in maintained inhibition of the subthalamic nucleus.
Hence the GP internal and SN pars reticular is not activated, the thalamus is not inhibited.
Therefore enables movement to occur.
What are the three different loops of the basal ganglia?
- Motor control
- Limbic control
- Associative loop
What is the motor loop of the basal ganglia?
input from the M1 and S1, balance of indirect (suppress unwanted movement) and the direct (inc wanted movement) to thalamus results in smooth movement control.
What is the function of the cognitive/association loop of the basal ganglia?
For motor learning and cognitive processing
For learning and evaluation movement - deciding what is the most effective solution
Active during training to complete motor skills. Streamlines motor processes by separating successful from unsuccessful during learning.
Projections from many cortical areas to the cuadate nucleus, particularly the nucleus accumbens (rewards confirming dopamingeric connections - reward after successful completion of a task), then projects to thalamus via direct and indirect pathways.
Projects back to cortical areas.
What is the role of the limbic loop?
Links basal ganglia to emotional processing areas - mediates postures, gestures and expressions related to emotion.
Limbic circuit hippocampus, amygdala and limbic lobe all project to the caudate nucleus, particularly the nucleus accumbens with dopaminergic properties.
Then projects via indirect and direct pathway to the thalamus, decides what emotion expression to suppress and what to express.
Thalamus projects back to the cerebral cortex.
What makes up the dorsal striatum?
The caudate and the putamen
What is the ventral striatum?
Consits of the nucleus accumbens and the olfactory tubercle that regulates function of the limbic system. (motivation, affect and reward)
What is the ventral palladium?
A component of the limbic loop of the basal ganglia.
What is the emrbyological origin of the subthalamic nucleus?
The diencephalon
Where is the substantia nigra located?
The midbrain
What structure is damaged during Parkinsons disease?
The substantia nigra.
What are the orange labels on this coronal cross section.
Thalamus
Putamen
Globus pallidus externus
Globus pallidus internus
Subthalamic nuclei
Substantia nigra
Tail of caudate nuclei
Globus pallidus
Body of the caudate nucleus
What are the purple labels on this image?
Choroid plexus
Temporal horn of the lateral ventricle
3rd ventricle
Body of the later ventricle
What are the green labels on this image?
Corpus callosum
INternal capsule
External capsule
Mamillary bodies
Hippocampus
Body of fornix
What are the lenticular nucleus?
Internal subcortical structure, bound by the internal and external capsule - contain the globus pallidus internus, externus and the putamen.
What are the blue labels on the image?
Cingulate gyrus
Claustrum
Optic tract
Insular lobe
What are the two different division of the corpus callosum?
The forceps minor - anterior
The forceps major - posterior
Label the structures on the transverse section of the brain?
Corpus callosum - forceps minor
Caudate head
Putamen
GPe
GPi
Thalamus
Caudate tail
Corpus callosum - forceps major
Internal capsule - anterior and psoteror limb
Claustrum
List the different cranial nerves and where in they exit the brain (e,g cerebral cortex, midbrain etc)
Olfactory - cerebral cortex
o - cerebral cortex
o - midbrain
t -midbrain
t - pons
a - pontomedullary junction
f - pontomedually junction
v - pontomedullary junction
g - medulla
v - medulla
a - medulla
h - medulla
What are the different Bamford classification of stroke?
Lacunar infarct
Total anterior circulation infarcts (TACI)
Partial anterior circulation infarct (PACI)
Posterior circulation infarcts (POCI)
What is a lacunar stroke?
A subcortical stroke - occurs secondary to small vessel disease.
No loss of higher cerebral function.
Only one of the following needs to be present:
- pure sensory stroke
- pure motor stroke
- sensorimotor stroke (contralateral motor and sensory loss)
- ataxic hemiparesis (ipsilateral ataxia and paresis)
What is a total anterior circulation stroke?
A large cortical stroke affecting areas of the brain supplied by both the middle and the anterior cerebral arteries.
All three of the following need to be present:
- unilateral weakness of face/arm/leg
- homonymous hemianopia
- higher cerebral dysfunction (visuospatial disorder ‘aka unable to recognise faces’ or dysphasia)
What is a partial anterior circulation stroke?
A less severe TACS, only part of the anterior circulation has been compromised.
Two of the following must be present:
- unilateral weakness (face, arm and leg)
- homonymous hemianopia
- higher cerebral dysfunction (dysphasia, visuospatial disorder_
What is a posterior circulation syndrome?
Damage to the brain supplied by posterior circulation e.g cerebellum and brainstem.
One of the following must be present for diagnosis of POCS:
- cranial nerve palsy and a contralateral motor/sensory deficit.
- bilateral motor/sensory deficit
- conjugate eye movement disorder
- cerebellar dysfunction (vertigo, ataxia)
- isolated homonymous hemianopia.
Identify the features of the midbrain
Cerebral aquaduct
Red nucleus
CN3 fibres
Crus cerebri (motor component of the cerebral peduncles)
Substantia nigra
CN3 nucleus
Superior colliculi
Identify the features of the pons
The superior cerebellar peduncle
Middle cerebellar peduncle
Corticospinal fibres
CNV fibres
4th ventricle
identify the features of the medulla
Dorsal motor nucleus of CNX
CNXII nucleus
CNXII fibres
Pyramids
Olives
Identify the features of the medulla
Pyramids
Medial lemniscus
Nucleus cuneate
Nucleus gracilis
Identify the features of the midbrain
CN4 nucleus
Crus cerebri
Substantia nigra
Red nucleus
Inferior colliculus
What is structure 2?
Caudate nucleus
What is structure A?
4th ventricle
This is a cross section of whic structure?
Midbrain
Which of the following structures has a role in the limbic system?
B - mamillary bodies
What structure is most associated with emotion and fear?
4 - amygdala
Which of the following subcortical structures is a major relay station for sensory and motor information?
4 - thalamus
In which region is the hippocampus?
Region 3
Fibres in this (ventral pontine) region carry which type of information.
Motor
What fibres types are found in region 1?
Commissual fibres
Aka corpus callosum
What strucutre is involved in homeostatis, feed behaviour and plays a role in the endocrine system?
4 - the hypothalamus
What is the difference between association fibres, projection fibres, commissural fibres and interneurons?
Association - a project between nearby regions on same side of cortex.
Projection fibres - .connects the cortex to other regions in the CNS e.g brainstem or cerebellum
Commissural fibre - connects to hemispheres of the brain
Interneurons - found in the spinal cord, connect motor and sensory neurons as well are varies signalling pathways.
What structures connect the cerebellum to the brainstem?
White matter tracts
The superior, middle and inferior cerebellar peduncles
What is the basic function of the cerebellum?
Control of movement
Describe the anatomical location of the cerebellum.
Within the posterior cranial fossa of the skull
Portion of the hindbrain
Caudal to the cerebrum and tentorium cerebelli
Dorsal to the brainstem.
Connects to midbrain, pons and medulla via the superior, middle and inferior cerebellar peduncles.
What is the posterolateral fissure of the cerebellum?
Demarcates the flocculonodular lobe
Seperates from the corpus cerebelli from flocculonodular lobe.
