Exam 4 - Part 2 Flashcards
What are the four divisions of the diencephalon?
- Epithalamus
- Dorsal thalamus
- Subthalamus
- Hypothalamus
What are the three parts of the epithalamus?
- Pineal gland
- Habenular
- Stria medullaris
What are the three parts of the dorsal thalamus and what divides it into these parts?
Anterior, medial, and lateral division nuclei; divided by internal medullary lamina
What are the two parts of the subthalamus?
- Subthalamic nuclei
2. Zona incerta
What is embedded in the internal medullary lamina?
Intralaminar nuclei
What covers the ventricular surface of the thalamus?
Midline nuclei
What partially surrounds/overlies the thalamus?
Thalamic reticular nuclei
What are the three functional groups of the thalamus?
- Specific or relay nuclei
- Association nuclei
- Non-specific nuclei
___ nuclei have well-defined inputs and projections.
Specific or relay
___ nuclei are reciprocally connected to the association cortex.
Association
___ nuclei are diffuse and function in arousal.
Non-specific nuclei
List the 7 specific/relay nuclei.
- Anterior
- Ventral anterior
- Ventral lateral
- Ventral posterior
- Lateral dorsal
- Medial geniculate
- Lateral geniculate
List the 3 association nuclei.
- Lateral posterior
- Pulvinar
- Medial dorsal
Lis the 2 non-specific nuclei.
- Intralaminar nuclei
2. Thalamic reticular nuclei
Where does the thalamic reticular nucleus receive information from and project information to?
From frontal cortices and thalamic nuclei to other thalamic nuclei (not to the cortex)
What is the input and projection of the VA/VL nuclei?
Input: basal ganglia, cerebellum
Output: motor areas
What is the input and projection of the VPL nuclei?
Input: medial lemniscus, spinothalamic tract (spinal components)
Output: somatosensory cortex
What is the input and projection of the VPM nuclei?
Input: medial lemniscus, spinothalamic tract (trigeminal components)
Output: somatosensory cortex
What is the input and projection of the medial geniculate?
Input: brachium of the inferior colliculus
Output: auditory cortex (transverse temporal gyri)
What is the input and projection of the lateral geniculate?
Input: optic tract
Output: visual cortex (occipital lobe)
What is the input and projection of the anterior nuclei?
Input: mammillothalamic tract
Outpu: cingulate gyrus
Compare and contrast S-units, FR-units, and FF-units with respect to size, type of muscle fiber, number of mitochondria and capillaries, twitch, force, and fatigue.
S-unit: small, type I, red fibers, lots of mitochondria and capillaries, slow twitch, small force, resistant to fatigue
FR-unit: medium, type IIa, white fibers, medium mitochondria and capillaries, fast twitch, moderate force, resistant to fatigue
FF-unit: large, type IIb, white fibers, few mitochondria and capillaries, fast twitch, large force, can be fatigued
What is a motor unit?
All muscle fibers innervated by a lower motor neuron
What is the size principle?
LMNs are recruited in order of size and force; slow/small units recruited first
What are upper motor neurons?
Corticospinal and corticobulbar neurons
What NT is released by lower motor neurons?
Acetylcholine
Describe the organization of lower motor neurons into groups (medial, lateral, dorsal, ventral).
Medial: trunk muscles
Lateral: distal limb muscles
Doral: flexor muscles
Ventral: extensor muscles
What are the 4 major control systems of the spinal cord LMNs?
- Reflex and pattern generators in the SC
- Descending pathways
- Cortical centers
- Basal ganglia/cerebellum
What are the 4 descending pathways and what do they control?
- Corticospinal tract (lateral): excitatory, release glutamate
- Vestibulospinal tract: postural adjustments/head movements
- Reticulospinal tract: locomotion and postural control
- Tectospinal tract: reflex turning of head to visual/auditory stimuli
What are the 4 cortical centers involved in controlling lower motor neurons?
- Association cortex (decides a movement is needed)
- Supplementary motor area (planning/learning complex movements)
- Premotor cortex (devise a plan for movements)
- Motor cortex (origin of commands to motor neurons)
What do the basal ganglia and cerebellum do?
Select/adjust movements to match intention
The CST passes through the ___ of the internal capsule.
Posterior limb
Which cranial nerves receive no direct corticobulbar innervation?
3, 4, and 6
What are the major divisions of the basal ganglia?
- Striatum (cadauate nucleus, nucleus accumbens, putamen)
- Globus pallidus (internal segment, external segment)
- Subthalamic nucleus
- Substantia nigra (compact part, reticular part)
What are the four basal ganglia circuits and what do they do?
- Motor loop: learned movements
- Cognitive loop: motor intention
- Limbic loop: emotional aspects of movement
- Oculomotor loops: voluntary saccades (fast eye movements)
Describe the direct motor pathway of the basal ganglia.
- Globus pallidus (internal segment) tonically inhibits VA/VL complex of thalamus with GABA.
- Association cortex excite the striatum with glutamate.
- Striatum inhibits globus pallidus
- VA/VL activated, stimulates premotor cortex
What is the basic circuity of the basal ganglia?
Thalamus -> Cortex -> Striatum -> GPi + SNr -> Thalamus
Describe the indirect motor pathway of the basal ganglia.
- Globus pallidus (external segment) tonically inhibits the subthalamic nucleus.
- Cortex excites striatum
- Striatum inhibits Globus pallidus (external segment)
- Subthalamic nucleus is disinhibited (it excites globus pallidus, internal segment)
- Thalmaus is inhibited
- Cortical activity is suppressed
How does substantia nigra affect the pathways of the basal ganglia?
D1 excites the striatum; D2 inhibits the striatum
What type of afferent information enters the cerebellar cortex?
Vestibular, proprioceptive, skin receptor, sensorimotor cortex, auditory/visual systems
Where do the outputs of the cerebellum travel to?
Motor systems (vestibular nuclei, thalamus, red nucleus/reticular formation)
True or false - there is no direct connection between the cerebellum and the spinal cord.
True
Describe the general flow of information through the cerebellum.
Inputs travel through mossy/climbing fibers to the cerebellar cortex, to Purkinje cells, to deep nuclei, out to motor systems
Describe the flow of information through the middle cerebellar peduncle.
- Information from cerebral cortex synapses on pontine nuclei.
- DECUSSATION occurs, then information travels to the middle cerebellar peduncle
- Information reaches the cerebellar cortex
Describe the flow of information through the inferior cerebellar peduncle.
- Information from the vestibular/cochlear nuclei, inferior olive, and dorsal spineocerebellar/cuneocerebellar tracts travels to the inferior peduncle. Only the information from the inferior olive DECUSSATES prior to reaching the peduncle.
- Information reaches the cerebellar cortex