Neuroanatomy Flashcards
What is typical entry point?
traverses gyri SMA (supplementary motor area)
What is the outer part of the brain called?
cortex, cortical surface of the brain
What do you want to avoid when entering the brain?
primary motor cortex, ventricles and sulci
What are sulci?
valleys, very vascular, not good to enter here
What are gyri?
mountains/hills, good place to enter because less risky
What is the coronal suture?
Where 2 plates come together, dip in skull, make burr hole here, keeps you close to SMA and away from primary motor cortex
What is AC?
anterior commisure, runs across, looks like handle bars
What are commisures?
good guides and reference points because everyone has them, similar from person to person, easy to get to functional targets, white matter fiber bundles, crossing from L to R hemisphere of the brain
What is PC?
posterior commisure
The distal contact is the most \_\_\_ in the brain? posterior anterior dorsal ventral
ventral
What is the pineal gland?
sits above the PC, good landmark
What areas are involved in typical trajectory?
cortex striatum (Caudate) or internal capsule thalamus Zona Inserta or Fields of Forel (grey matter) STN SNr
What part of the STN is typically best to stimulate?
motor, dorsal and lateral
dorsolateral
What is a typical DBS lead trajectory?
pre-coronal entry point passes through the prefrontal cortex, subcortical white matter, the anterior limb of the internal capsule and the basal ganglia
What are the divisions of the STN? Why is this important?
Emotional/Limbic
Motor/Movement
Cognitive
We don’t just want to blow up the STN with energy, we generally want to be in the motor part of STN, the dorsal lateral portion, this is why we do MER
What is the anterior division of the STN responsible for?
emotional
What is the dorsal lateral division of the STN responsible for?
motor/movement (largest)
What is the medial part of the STN responsible for?
cognitive (associative)
What is halfway between the AC and PC?
Mid commisural (MC)
What are the typical coordinate for STN from MC?
Lateral: 12mm
Inferior: 3mm center of motor (STN), 4-5mm bottom of nucleus
Posterior: 3mm
What 2 parts of the brain make up the striatum? How do you describe what they look like?
Caudate and Putamen, caudate looks like a snake and the putamen looks like an egg that the caudate wraps around
What is the lemon wedge shape of matter above the pallidus?
Putamen
What lies lateral to the STN? (dark matter)
posterior limb of internal capsule (IC)
What lies on the other side lateral to the Internal Capsule? (STN on one side, what’s on the other)
globus pallidus
What separates the lobes of the brain?
fissures
what are the 4 lobes of the brain?
frontal, parietal, occipital, temporal
Which lobe is associated with reasoning, motor skills, and expressive language?
frontal
T/F Substantia Nigra is a main target for DBS Surgery.
F
Which lobe do surgeons generally attempt to pass the lead through?
frontal lobe
Explain the direct vs indirect pathway.
Direct Pathway: cortex-striatum-thalamus
overall effect: facilitates movement
Indirect Pathway: cortex-striatum-GPe-STN-GPi-thalamus
overall effect: inhibits movement
What is the trajectory once the physician is in the STN?
Thalamus: 20mm TO START
Zona Inserta: 8mm
STN: 4-5mm (or higher)
SNr: 1mm below target
What is STN target for DBS?
dorsal and lateral
What are the indirect coordinates for targeting the GPI?
We are targeting the lateral, inferior border (medial would be the internal capsule)
Lateral: 17.5mm from the wall of the 3rd ventricle
Anterior: 2mm from MC
Inferior: 5mm from MC
What are the indirect coordinates for targeting ViM
Lateral: 11.5mm
Posterior: 2 1/2 - 3 1/2 mm fraction of the AC/PC line length
Anterior: to the PC
What is ring mode and why is this important?
single source, when using more than 1 contact, is not voltage controlled or current controlled, it is impedance controlled, MICC is true ring mode because you can control energy circumferentially`
What are the components of the Basil Ganglia?
Caudate: striatum and putamen
Globus Pallidus: GPe and GPi
Subthalamic Nucleus: STN
Substantial Nigra: SNr
What is a neuron?
cells that transmit information: sensory, motor and interneurons, in general motor neurons control the symptoms associated with PD
Explain neuron communication
- dendrites collect electrical signals, receivers
- cell body integrates incoming signals and generates outgoing signal to axon
- axon: passes electrical signals to dendrites of another cell (transmitters)
What are the four distinct phases of an action potential?
resting sate: neuron is not sending signals and inside of the cell has a negative charge
depolarizing state: a stimulus causes the sodium channels to open, the negatively charged neuron causes positive sodium ions to rush in, the inside of the neuron becomes momentarily positively charged and its said to be depolarized
repolarizing state: the depolarization of the neuron leads to the opening of the potassium channels, allowing positive ions to leave the cell, the cell is back in the negative range
undershoot: refractory period since it is the very short period when another action potential is not possible
