Unit 6: Internal brain Flashcards
What is the function of the brainstem?
Pathways of connection between the brain, spinal cord and cerebellum
Contains important nuclei
Important for survival and cognitive functioning
What are the three divisions of the brainstem?
The midbrain
The pons
The medulla oblangata
What is the function of the medulla oblangat?
Where the brain connects with the spinal cord
Contains nuclei for the regulation of essential survival systems such as the respiratory and cardiovascular system.
Contains nuclei that are involved in reflexes such as sneezing, coughing, vomitting etc.
Some cranial nerves exit the brainstem at the level of the medulla
What is the function of the pons?
Connects the medulla oblangat to the brainstem
Contains nuclei of the cranial nerves, deals with sensation and movement of the head and space
Deals with autonomic functions like tear and saliva production
What four bumps are found on the midbrain and what is there function?
On the posterior surface of the midbrain there are four bumps that make up the superior and inferior colliculi
The superior colliculi are involved in eye movements and vision processing
The inferior colliculi are involved in auditory processing
What are the major dopamine producing nuclei of the brain?
The ventral tegmental area
The substantia nigra
What is the function of the tegemental area?
Major dopamine production
INvolved in motivation and reward
Found in the midbrain
What is the function of the substantia nigra?
Major dopamine production
Movement
Found in the midbrain
What are the different basal ganglia?
Found deep within the cerebral hemisphers and the brainstem
Contains the
-putamen
-caudate
-globus pallidus
-subthalamic nucleus
-substantia nigra
What is the striatum in relation to the basal ganglia?
Combined name for the putamen and caudate
What is the main role of the basal ganglia?
Facilitates movement by regulating and co-ordinating activity from other areas of the brain using the direct and indirect pathway
How are the basal ganglia split into the main input and output nuclei?
The putamen and caudate are the main input nuclei meaning they receives information from the cerebral cortex
The main output nuclei are the substantia nigra and the globus pallidus, these send information to the primary motor cortex by the thalamus and to the nuclei in the brain stem.
What are the subdivisions of the globus pallidus?
The internal and external segment
What are the subdivisions of the substantia nigra?
Pars compacta
Pars reticulata
Describe how the direct pathway in the basal ganglia initiates movement?
The globus pallidus internus and the substantia nigra pars reticulata send inhibitory signals to the thalamus (GABA)
When movement wants to be activated the cerebral cortex send excitatory information to the striatum (glutamate), the substantia nigra also send excitatory information to the striatum.
The striatum send inhibitory signals (GABA) to the gpi and sgpr.
This allows excitatory signals to be sent from the thalamus to the primary motor cortex, initiating movement
Describe the indirect pathway in relation to the basal ganglia?
The globus pallidus externus typically sends inhibitory signals to the subthalamic nucleus
In the inhibitory pathway the cerebral cortex activates the striatum which inhibits the globus pallidus externus
The cerebral cortex also activates the subthalamic nucleus to send activatory signals to the globus pallidus internus and the substantia nigra, these inhibit the thalamus preventing the initiation of movement
How is the indirect pathway modulated?
The indirect pathway inhibits movement
In order to stop its effect the substantia nigra pars compacta send inhibitory signals to the striatum, this means the globus palidus externus remains active.
Downstream less inhibitory signals are sent the the thalamus so it is able to initiate activity in the cerebral cortex.
What view of the midbrain is this?
Anterior
What view of the midbrain is this?
Posterior
What is the cerebral peduncle function?
A bundle of axons connecting the brainstem to the cerebrum
What is the function of the superior, middle and inferior cerebellar peduncles?
Branch off from the pons, connect the cerebellum to the midbrain and the cerebrum
What is the function of the inferior and superior colliculi?
The superior colliculi has a role in the visual pathway
The inferior colliculi has a role in the auditory pathway.
Identify the midbrain, pons and medullar
The midbrain is the purple section
The pons is the second grey section
The medulla is the blue and yellow section
What cerebral cortex structure is connected superiorly to the mdibrain?
The thalamus
Describe the terminology cortex, cerebrum, cerebral cortex and cortical.
The cortex/cortical is the superfificial part of the brain (the grey matter)
The cerebrum grey and white matter
The cerebral cortex is all of the above
Identify the different parts of the anterior brainstem
Top grey is the thalamus (not part of the brainstem)
THe purple is the cerebral peduncles
The bottom grey is the pons
The yellow is the pyramids
The blue is the olives
The cross in the pyramids section is the desiccation of the pyramids
What is the function of the desiccation of the pyramids?
A point for axon tracts in the medulla to cross to the contralateral side of the body, including the lateral corticospinal tract.
Identify the structures of the posterior surface of the brainstem.
The grey top is the thalamus (not part of the brainstem)
The purple is the cerebral peduncles
The green is the superior and inferior collilculi
The large dark red is the middle cerebellar peduncles
The light red and the pink are the superior and inferior cerebellar peduncles
The light blue is the floor of the fourth ventricle
THe final grey section is the medulla
Orientate the image of the midbrain transverse section and identify the labelled images?
Like a mouse - ears are dorsal and the nose is ventral
1. cerebral peduncles
2. substantia nigra
3. cerebral acqueduct
4. the superior/inferior colliculi
Orientate yourself using the structure of the pons and identify the key features
Dorsal has the flatter but wavy edge (made by the CSF)
Ventral has the two bumps
1. Floor of the fourth ventricle
3. corticospinal tract
4. middle cerebellar peduncles (ones viewed varies on height level)
Orientate yourself in the transverse cross-section of the medulla and identify the key features
Dorsal is the top of the image (more gradula decrease and bigger sides)
Ventral is the front with a sudden dip
1. Olives
2. Pyramids
3. Anterior median fissure
What plane is this image taken in?
Identify the key structures.
This is a coronal section of all the basal ganglia
1. lateral ventricle
2. caudate nucleus
3. internal capsule
4. putamen
5. globus pallidus
6. Thalamus
7. Third ventricle
What plane is this image taken in?
Identify the key structures
This is an anterior coronal sections, so only contains some of the basal ganglia
1. lateral ventricle
2. caudate nucleus
3. internal capusle
4. putamen
What plane is this image taken in?
Identify some of the key structures
This image is taken in the axial plane
It contains the lateral ventricles medially and the caudate nuclues laterally.
It is too superior to contain the rest of the basal ganglia
What plane is this image taken in?
Identify some of the key features
This image is taken in the axial plane
It contains all of the basal ganglia
1. lateral ventricle
2. caudate nucleus
3. Putamen
4.Thalamus
5. third ventricle
What plane is this image taken in?
Identify some of the key features
This is an axial section of the more inferior aspect of the brain
1. Caudate nucleus
2. Putamen
3. Globus Pallidus
4. Thalamus
What is the clinical importance of a tumour in the pituitary gland?
What bone is the pituitary fossa part of?
Pressure on the optic chiasm, can cause disruption in th eoptic field.
Note pituairy fossa is in the sphenoid bone
Where is the spinothalamic tract located in a vertebral cross section?
C shape around the ventral horn.
Where is the Lissauers fasiculus located in the vertebral cross section?
Off the tip of the dorsal horn
Give a detailed description of the spinothalamic tract.
Is a sesnory tract
Primary neurone cell body is in the dorsal root ganglion, travels up/down on or two levels in the spinal cord in the lissauers fasiculus.
Then synapses in the nucleus propius in the dorsal horn
The secondary neuron desicates to the contralateral side and travels up the white mater spinothalamic tract to the brain stem and up to synapse in the thalamus
The tertiey neuron carriers information from the thalamus to the primary somatosensory cortex.
What receptors may trigger the DCML pathway?
Fine touch and proprioception
1. Pacinian corpuscle
2. Meissners corpuscle
3. Ruffini endings
4 Merkel Cells.
What is the function of the vermis in the cerebellum?
Divides the cerebellum into left and right hemispheres.
What is the function of the primary and horizontal fissure in the cerebellum?
The pirmay fissure seperates the posterior lobe from the anterior lobe
The horizontal fissure seperats the posterior lobes from the inferior posterior lobe
What surface of the cerebellum is shown?
Label the structures
The dorsal surface
1. Anterior lobe
2. Posterior lobe
3. Primary fissure
4. Horizontal fissure
5. Vormis
6. Tonsils
What surface of the cerebellum is shown?
Label the structures
The ventral surface, (where it connects to the brainstem)
1. vormis
2. superior peduncles
3. middlepeduncle
4. inferior peduncle
5. THe flocculos
6. THe nodule
What makes up the limbic lobe?
A theoretical lobe containing parts of the parietal and the temporal lobe
Consists of the cingulate gyrus and the parahippocampal gyrus.
What is the normal range of CSF in an adult?
90-200ml
What is the pathophysiology when there is too much CSF?
Hydrocephalus
The accumulation of CSF in the subarachnoid space or the ventricles
This causes the ventricles to expand and exert pressure on the surrounding structures in the brain.
Often causes increased intracranial pressure
Symptoms include thin scalp with visible veins, downwards pointing eyes, headache, vommitting, irritability.
