Brain: How it grows and works (43b - 53b) Flashcards
Including what each part of the brain does
Which efferent pathway is involved in generating movement?
Corticostriate
Which MRI technique is used to evaluate contrast enhancement?
T1
- Great anatomic detail, but less sensitive to pathology
Occlusion of which artery leads to contralateral motor and sensory deficits in the lower limb?
Anterior cerebral artery
What is the most medial aspect of the temporal lobe?
The uncus of the temporal lobe
Clinical significance: swelling can compress the oculomotor nerve
A
- Loss of motor function: cortical spinal tract bilaterally
- Loss of Pain and temperature: loss of both spinothalamic tracts
- Preservation of other senses because posterior column is intact
Which areas of the brain are supplied by the posterior cerebral artery?
Occlusion leads to what deficits?
- Occipital lobe
- Inferior temporal lobe
- Posterior limb of the internal capsule
Loss of contralateral visual fields, color vision, visual/spatial problems
(Minimal motor or sensory deficits)
What neurotransmitter is synthesized in the raphe nuclei?
Serotonin
The outermost layer of the neocortex is layer ___
This layer developes [latest/earliest]
The outermost layer of the neocortex is layer 1
This layer developes latest
- Layer 6 is the innermost layer and develops first
- Neurons of subsequent layers prolifereate, differentiate, and then migrate from deep to superficial
- Layer 6 neurons are the oldest, while layer 1 neurons are the youngest
At what gestational age can 6 cortical layers be identified?
18 weeks post conception
What makes up a “disynaptic pathway?”
Sensory neuron + interneuron + motor neuron
A 63yo man with a history of hypertension, hyperlipidemia, and diabetes presents with acute onset of weakness and numbness of the right face and arm, global aphasia, and a left gaze palsy.
He is able to raise his right leg.
A stroke due to occlusion of what artery might cause these symptoms?
Middle cerebral artery
- Supplies the lateral surface of the frontal, parietal, and temporal lobes
- Language areas
- Motor cortex
A lateral lesion in the brainstem, as occurs in the lateral medullary syndrome, will damage which of the following cranial nerve nuclei?
- Hypoglossal nucleus
- Trochlear nucleus
- Abducens nucleus
- Oculomotor nucleus
- Spinal nucleus of V
E. Spinal nucleus of V
- A lateral lesion will damage sensory nuclei
- All other options are motor nuclei
Which cortical layer receives thalamic input?
Which cortical layer sends output back to the thalamus?
Which cortical layer receives thalamic input? Layer IV
Which cortical layer sends output back to the thalamus? Layer VI
What does fMRI measure?
What is this technique used for?
fMRI measures deoxyhemoglobin
- Helps us assess which areas of the brain are using the most oxygen
- It is an indirect measurement of electrical activity in the brain
- Used to determine which areas are used in different functions so they can be avoided during surgery
A 21 year old man with a history of precocious puberty presents for evaluation of transient episodes characterized by uncontrolled laughing?
Which image best fits this description?
iii
- Hypothalamus
- Produces hormones involed in endocrine axes
Which structures are contained in the tegmentum of the midbrain?
- Red nucleus
- Principle sensory nucleus of the trigeminal nerve
- Reticular formation
- Substantia nigra
At what level of the brainstem is the decussation of the pyramids?
Spinomedullary junction
What is the etiology of Rett syndrome?
Disorder of synaptogenesis
The [area of the brain] is the relay from the brainstem to the cerebral cortex
The diencephalon is the relay from the brainstem to the cerebral cortex
Contains the thalamus
Which nerve exits throught the intervertebral foramen between the C6 and C7 vertebrae?
The C7 spinal nerve
Although there are seven cervical vertebrae (C1-C7), there are eight cervical nerves C1–C8. C1–C7 emerge above their corresponding vertebrae, while C8 emerges below the C7 vertebra. Elsewhere in the spine, the nerve emerges below the vertebra with the same name (T1 nerve emerges below T1 vertebrae, etc)
What neurotransmitter is synthesized in the ventral area of the tegmentum?
Dopamine
CSF appears bright in [T1/T2] weighted MRIs
CSF appears bright in T2 weighted MRIs
Loss of pain and temperature sensation on the right side of the face might be due to a lesion in which tract?
Right spinal tract of V
Trigeminal lemniscus carries proprioception, touch, pressure, vibration
(Aka right trigeminothalamic tract)
A 60 y.o. male presents with dysphagia, decreased coordination (falling to left side), and left lower facial droop after a bicycle accident in which he hyperextended his neck. On imaging, he is found to have a stroke.
Which brain structures are most likely affected?
Left cerebellum
(likely medial/intermediat stuructures if posture is affected)
Which areas of the brain are supplied by the anteror cerebral artery?
What are the consequences of occluding this artery?
Medial surfaces of the frontal, parietal, and temporal lobes
Contralateral motor and sensory deficits in the lower limb
Which structure is labeled by D?
Third ventricle
- This is a T2 weighted MRI
- CSF is bright
What are the 4 types of glial cells?
Ependymal
Astrocytes
Microglia
Oligodendrocytes
A 44 y.o. woman presents with posterior headaches which are worse with coughing and straining as well as swallowing difficulty and frequent choking on foods. She is told she has a Chiari I malformation.
Which part of the cerebellum is used to diagnose this condition?
Cerebellar tonsils
The cell bodies of the first order neurons for proprioception from the face are located in which nucleus?
Mesencephalic nucleus
Which primodial tissue layers form the dura, arachnoid, and pia mater?
- Dura - Mesenchyme
- Arachnoid - Neural Crest Cells
- Pia - Neural Crest Cells
A 73 year old man presents with right inferior quadrantopsia
Which image best fits this description?
i
- Issues with vision = problem with the visual cortex, which is located in the occipital lobe
Radial crest cells expressing Nkx2 or Gsx2 will become [inhibitory/excitatory] neurons
Radial crest cells expressing Nkx2 or Gsx2 will become inhibiotry neurons
A lesion in the right ventral medulla will most likely affect which spinal tract?
Describe the effects
Left corticospinal tract
-> Left hemiparesis
In general, the medial aspects of the motor and sensory homunculi are associated with the _________, while the lateral surfaces are associated with the __________
In general, the medial aspects of the motor and sensory homunculi are associated with the legs** , while the lateral surfaces are associated with the **face and arms
E
The amygdala - in the superior, medial portion of the temporal lobe
What neurotransmitter is synthesized in the locus coeruleus?
Norepinephrine
A patient is experiencing loss of right visual fields, color vision, and ability to solve visual spacial problems.
There are no motor or sensory changes.
Which artery is likely occluded?
Left posterior cerebral artery
Supplies the occipital lobe, which is where we process visual information
B - Stria terminalis
How many weeks post-conception does gastrulation occur?
3 weeks
A 29 y.o. female presents with headaches and double vision. She is found to be tilting her head to the left.
Which structures are likely involved?
- Hypothalamus and optic chiasm
- Midbrain at the level of superior colliculus
- Left cerebellum and lateral medulla
- Right cerebellum and lateral medulla
b. Midbrain at the level of superior colliculus
* Superior colliculus is involved with reflexive eye movements
A 31 year old man presents with truncal ataxia and nausea
Which image best fits this description?
ii
- This sounds like a cerebellar issue
- Image ii is pointing to the cerebellum
Where are motor nerve fibers found?
J
Which structure is labeled by B?
Crus cerebri
(V hard to tell….)
Which imaging modality was used to produce this image?
Be specific
T2 weighted MRI
- White matter is darker than grey matter
- CSF is bright
Most local interneurons of the neocortex are [pyramidal/stellate]
Most local interneurons of the neocortex are stellate
Which neuromodulator has a major source of origin (cell bodies) in the telencephalon?
Acetylcholine
What is the purpose of the ventral pons?
Corticocerebellar relay
Which layer of the neocortex contains fusiform neurons?
Layer VI
An 81 year old man presents with weakness and numbness in his left leg
Which image best fits this description?
iv
- Motor homunculus: medial aspects are involved in leg actions
- This looks like a pretty medial sagittal slice, in the right area for the motor homunculus in the postcentral gyrus
Which structure is labeled by A?
Hippocampus
D
Corticospinal tract
The corticospinal tract (pyramid) is in the ventral medulla, while the dorsal column/medial lemniscus pathway (dorsal column nucleus) is in the dorsal medulla
Global aphasia is associated with occlusion of which artery?
What other signs may be present?
Middle cerebral artery, usually left (dominant side)
- If the dominant side is affected specifically, global aphasia occurs
- In general, if an MCA is occluded:
- Contralateral face and arm weakenss and numbness
- Contralateral hemianopsia
- Gaze preference - looks toward lesion side/away from affected limb
- Dysarthria
Occlusion of the posterior spinal arteries damages which spinal tract?
Dorsal column/medial lemniscus
-> posterior cord syndrome
Which cells make up the blood brain barreir?
Astrocytes
+
Endothelial cells of brain capillaries
What is the most common developmental disorder of the human forebrain?
Holoprosencephaly
Which section of the brain controls voluntary movement?
Cerebellum
- Balance
- Motor movement
- Coordination
Which letter labels sensory fibers exclusively?
B
Which lobe of the cortex is most involved in our personality?
Frontal
Where is the blood brain barrier weakest or absent?
Circumventricular organs
- Pineal gland
- Area postrema
The [area of the brain] contains the cerebro-cerebellar relay
The pons contains the cerebro-cerebellar relay
Which artery supplies the areas of the brain responsible for sensation and interpretation of visual input?
Posterior cerebral atery
What neurotransmitter is synthesized in the basal forebrain nuclei?
ACh
A mass in which legion is most likely to block CSF flow from the 3rd ventricle to the 4th ventricle?
- Right lateral ventricle
- Foramen of Monro
- Pineal region
- Foramen of Magendie
c. Pineal region
The pineal gland sits at the rostal portion of the cerebral aqueduct
Blockage of the cerebral aqueduct prevents CSF from flowing from the 3rd -> 4th ventricle
SO a pineal gland tumor could block the flow of CSF from the 3rd to the 4th ventricle
What is dyspraxia?
It is associated with a lesion in which area of the brain?
- Inabiltiy to plan/process motor tasks
- Can’t voluntarily do a task, even though the limb is working and understanding of the task is there
- Associated with frontal lobe damage
- May be due to occlusion of the anterior cerebral artery
The [area of the brain] is responsible for auditory and visual orientation/attention and oculomotor control
The midbrain is responsible for auditory and visual orientation/attention and oculomotor control
Radial crest cells expressing Pax6 will become [inhibitory/excitatory] neurons
Radial crest cells expressing Pax6 will become excitatory neurons
The [area of the brain] is the major route of communication between cerebral hemispheres
The corpus callosum is the major route of communication between cerebral hemispheres
Why does blood appear bright on a CT of the brain?
- Hemoglobin blocks the radiowaves -> brightness
- For blood to appear white, hemoglobin must be intact
- If a bleed is old, hemoglobin breaks down and will no longer appear bright
What begins first: neuronal development or glial development?
Neuronal development
After the neurons develop, glial cells are required for synaptic formation
The [area of the brain] is responsible for autonomic control, neuromodulators, and sensory and motor relays
The medulla is responsible for autonomic control, neuromodulators, and sensory and motor relays
Which layer of the neocortex is the thalamic reciprocal projection layer?
What does this mean?
Layer VI - the fusiform layer
- While layer IV is the main thalamic receiving layer, layer VI also receives some input from the thalamus
- Layer VI sends these signals back to the thalamus so that they are sent to layer IV
Note: Layer VI contains many differently shaped neurons, while layer IV contains mostly stellate
(I think this is how it works, if you have a better explanation please lmk)
C - subarachnoid space
What neurotransmitter is synthesized in the tuberomammillary nucleus?
Histamine
Which areas of the brain are supplied by the middle cerebral artery?
What are the consequences of occluding this artery?
Lateral surfaces of the frontal, parietal, and temporal lobes
Contralateral motor and sensory deficits in the face and hand
Global aphasia if left MCA is occluded
What structure forms during neurulation?
Neural tube
The [area of the brain] contains sensory and motor nerves and is responsible for reflexes
The spinal cord contains sensory and motor nerves and is responsible for reflexes
The [area of the brain] is responsible for motor control, sensory processing for motor control, and balance
The cerebellum is responsible for motor control, sensory processing for motor control, and balance
In general, which layers of the neocortext are considered granular?
Which are considered stellate?
-
Granular: II, IV, VI
- Although layer VI has many different kinds of neurons
- Stellate: III, V
- Layer I is not well understood, and doesn’t have many neurons
What usually causes central cord syndrome?
Spinal stenosis (in older patients)
After a high-speed trauma w/flexion and extension
Causes compression of the spinal cord inside of the bony canal, leading to damage in the center of the spinal cord
Afects cervical innervations most; motor and sensory pathways in arms and hands > legs/feet
The [area of the brain] is responsible for sensation, perception, movement, consciousness, attention, cognition, and memory
The cerebral hemisphere is responsible for sensation, perception, movement, consciousness, attention, cognition, and memory
Cerebral hemisphere = cerebral cortex?
B
The dorsal column medial leminiscus in the spinal cord is ipsilateral to the body parts it supplies
A patient presents with right hemiplegia of the arm and leg combined with right lower facial paralysis and sensory deficits in the right face, arm, and leg.
Where is the most likely location of the stroke?
- Left posterior limb of the internal capsule near the genu
- Left middle cerebral artery
- Right posterior limb of the internal capsule near the genu
- Right middle cerebral artery
- Left middle and anterior cerebral arteries
A. Left posterior limb of the internal capsule near the genu
- A stroke of the posterior limb would affect botht the corticospinal and corticobulbar tracts
- This is more likely than a storke of botht the middle and anterior cerebral arteries
A patient is seen who has paralysis of the right upper and lower face caused by a stroke of the facial motor nucleus. Additionally, he has loss of pain and temperature over the right side of the face and the left side of the body (alternating hemianesthesia). His lesion is probably located in the:
- Left lateral pons
- Right lateral medulla
- Right lateral pons
- Left lateral medulla
- Right posterior limb of the internal capsule
C. Right lateral pons
- The facial motor nucleus and spinal nucleus of V are both located in the pons
- Although it kind of looks like the spinal nucleus of V is both in the medulla and the pons?
What are fasciculi and funiculiin the brain?
Large white matter pathways
Damage to the anterior spinal artery causes damage to which major spinal tracts?
Corticospinal tract
Spinothalamic tract
(also Spinocerebellar from guiding questions)
This is anterior cord syndrome
Basically, everything except the dorsal column/medial lemniscus pathway is cut off
What is the first intradural branch of the internal carotid artery?
Ophthalmic artery
Which neurotransmitter modulates our highest functions?
(Cognition, consciousness, highest learning and memory)?
ACh
Occlusion of which artery leads to:
- Contralateral motor and sensory deficits in the face and hand
- Global aphasia
Left middle cerebral artery
(Language areas are in the left hemisphere)
Which structure is labeled by C?
Temporal horn/inferior horn of the lateral ventricle
- Can tell its filled with CSF becaues its bright
- This is a T2 weighted MRI
