Neuro Test 3 Flashcards
What pathways go through the thalamus? Name everything that goes through the thalamus. “it’s not hard, but anyway…”
All sensory input except olfactory travels through the thalamus. Cerebellum, Basal ganglia, and limbic structures.
The divisions of the thalamus. Know what they are, and what determines how they are separated, know their location.
The divisions are anterior, medial, lateral, intralaminar nuclei, reticular nucleus. The internal medullary lamina divides into medial and lateral groups nuclei. The internal medullary lamina superiorly devised around the anterior nucleus.
Name the type of inputs that are in the thalamus. The categories.
There are two classes of sensory inputs; specific inputs and regulatory input.
Specific input: sensory pathways, Basal ganglia, cerebellum, limbic system, cerebral cortex.
Regulatory input: Association areas of the cerebral cortex, thalamic reticular nucleus, reticular formation.
What are the functions of the inputs in the thalamus. Demonstrate an understanding of the inputs, that part of the brain they go to, and what types of decisions they are making.
Specific inputs: the input delivers information to a thalamic nucleus that will be passed on to the cerebral cortex.
Regulatory inputs: these inputs send information that is used to determine whether a message from a specific input is sent on to the cerebral cortex, and where it is sent within the cerebral cortex.
A tumor of the pineal gland. What night it look like?
A tumor of the pineal gland causes hydrocephalus which is extra fluid in the brain from compression of the aqueduct.
Eye-movement deflects and pupillary reaction deficits occur due to compression of cranial nerves three and four.
Changes in sexual development of youth.
There are projection nerve fibers that leave the thalamus, what are the areas those go to?
One. Projection nuclei–project to functional areas of cerebral cortex
Too. Association nuclei–parietal-occipital-Temporel cortex, prefrontal cortex
Three. Nonspecific nuclei–axons are widely distributed.
The internal capsule and Corona radiata. No the pathway from the brainstem to the cortex. Label and visualize the components.
Brainstem
Internal Capsule
Corona Radiata
Cerebral Cortex
Tonic and burst mode. How does that happen? What does it do? When does it function?
Tonic mode starts at -55 mV, Slightly depolarized. (occurs when paying Attention in class) it causes a train of action potentials. Magnitude is the frequency of the train
Burst mode begins at -77 mV, hyperpolarized. Occurs during sleep. Voltage gated calcium channels cause burst mode. The inactivation period Lasts for 100 ms or more.
Know the blood supply to the thalamus.
Branches of the posterior cerebral artery
Posterior choroidal artery = dorsimedial region
Perforating arteries of posterior cerebral artery and posterior communicating artery
Know the difference between thalamic pain and thalamic syndrome. Structurally, what makes the difference?
Thalamic pain “Central Pain Syndrome” secondary to a vascular accident in the posterior thalamus. This condition causes severe pain on the contralateral side of the body. Pain is drug-resistant.
Thalamic syndrome–A combination of thalamic pain, hemionesthesia, and sensory ataxia from a contralateral lesion of the medial lemniscus pathway and extensive posterior thalamic damage.
Name the various types of motor neurons and what types of motor fibers they innervate. Name the type of lower motoneuron with type of fiber it innervates.
S–smallest alpha motoneurons innervate red muscle fiber. Slow twitch.
FF–the largest alpha motoneurons innervate white muscle fiber. Fast twitch, Fatigues.
FR–intermediate Alpha motoneurons innervate intermediate muscle fiber. Fast twitch, fatigue resistant.
(most muscles have all 35 retypes randomly intermingled within the muscle… Proportions vary)
Understand how the synaptic current (synaptic drive) works to recruit the type of motor neurons as well as muscle fibers… How is it graded?
In order of size.
Smaller are recruited first because the size allows smaller ones action potentials first… not transmission of nerve impulse but how easily they are recruited. Smaller neurons have greater membrane potential changes for the given amount of synaptic currents.
As the synaptic drive reaches the anterior horn, S units are first, FR units are second, and FF are third.
This order of recruitment gives a progressively smooth increase during an increase in muscle contractile force.
This is an automatic phenomenon.
Need to know all the descending motor pathways to the brain and spinal cord–the names of those. 4
Corticospinal Tract
Medullary Reticulospinal Tract
Tectospinal Tract
Rubrospinal Tract
What is the corticospinal tract? What structures does it to send through from the cortex through the spinal column? 8
- precentral gyrus
- posterior internal capsule
- cerebral peduncle of the rostral midbrain (crus cerebri)
- Basal Pons
- Pyramids of the medulla.
- at the caudal medulla level, 85% of fibers decussate at pyramidal decussation.
- 85% descends in the lateral corticospinal tract.
- 15% descend in the uncrossed Anterior Corticospinal Tract. Most of these are headed to the axial skeletal muscle.
What are the descending tracts of the spinal cord? 6
Posterior to anterior
- Lateral Corticospinal Tract
- Rubrospinal Tract
- Lateral Reticulospinal Tract
- Medial Reticulospinal Tract
- Vestibulospinal Tract
- Ventral Corticospinal Tract
