Flashcards in Exam 4 - Part 2 Deck (114):
What are the four divisions of the diencephalon?
2. Dorsal thalamus
What are the three parts of the epithalamus?
1. Pineal gland
3. 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?
1. Subthalamic nuclei
2. Zona incerta
What is embedded in the internal medullary lamina?
What covers the ventricular surface of the thalamus?
What partially surrounds/overlies the thalamus?
Thalamic reticular nuclei
What are the three functional groups of the thalamus?
1. Specific or relay nuclei
2. Association nuclei
3. Non-specific nuclei
___ nuclei have well-defined inputs and projections.
Specific or relay
___ nuclei are reciprocally connected to the association cortex.
___ nuclei are diffuse and function in arousal.
List the 7 specific/relay nuclei.
2. Ventral anterior
3. Ventral lateral
4. Ventral posterior
5. Lateral dorsal
6. Medial geniculate
7. Lateral geniculate
List the 3 association nuclei.
1. Lateral posterior
3. Medial dorsal
Lis the 2 non-specific nuclei.
1. 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?
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?
1. Reflex and pattern generators in the SC
2. Descending pathways
3. Cortical centers
4. Basal ganglia/cerebellum
What are the 4 descending pathways and what do they control?
1. Corticospinal tract (lateral): excitatory, release glutamate
2. Vestibulospinal tract: postural adjustments/head movements
3. Reticulospinal tract: locomotion and postural control
4. Tectospinal tract: reflex turning of head to visual/auditory stimuli
What are the 4 cortical centers involved in controlling lower motor neurons?
1. Association cortex (decides a movement is needed)
2. Supplementary motor area (planning/learning complex movements)
3. Premotor cortex (devise a plan for movements)
4. 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.
Which cranial nerves receive no direct corticobulbar innervation?
3, 4, and 6
What are the major divisions of the basal ganglia?
1. Striatum (cadauate nucleus, nucleus accumbens, putamen)
2. Globus pallidus (internal segment, external segment)
3. Subthalamic nucleus
4. Substantia nigra (compact part, reticular part)
What are the four basal ganglia circuits and what do they do?
1. Motor loop: learned movements
2. Cognitive loop: motor intention
3. Limbic loop: emotional aspects of movement
4. Oculomotor loops: voluntary saccades (fast eye movements)
Describe the direct motor pathway of the basal ganglia.
1. Globus pallidus (internal segment) tonically inhibits VA/VL complex of thalamus with GABA.
2. Association cortex excite the striatum with glutamate.
3. Striatum inhibits globus pallidus
4. 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.
1. Globus pallidus (external segment) tonically inhibits the subthalamic nucleus.
2. Cortex excites striatum
3. Striatum inhibits Globus pallidus (external segment)
4. Subthalamic nucleus is disinhibited (it excites globus pallidus, internal segment)
5. Thalmaus is inhibited
6. 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.
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.
1. Information from cerebral cortex synapses on pontine nuclei.
2. DECUSSATION occurs, then information travels to the middle cerebellar peduncle
3. Information reaches the cerebellar cortex
Describe the flow of information through the inferior cerebellar peduncle.
1. 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.
2. Information reaches the cerebellar cortex
Where do climbing fibers come from?
The majority of fibers in the cerebellum are ___ (mossy or climbing).
What are some of the deep cerebellar nuclei?
Dentate nucleus, interposed nucleus, fastigial nucleus
The superior cerebellar peduncle receives afferent information from the ___.
Anterior spinocerebellar tract
The middle cerebellar peduncle receives afferent information from the ___.
The inferior cerebellar peduncle receives afferent information from the ___.
1. Inferior olivary nucleus
2. Vestibular nuclei
3. Spinal cord
4. Trigeminal nuclei
5. Reticular formation
The only axons that leave the cerebellar cortex are from the ___ cells.
Where do axons from basket cells synapse? Stellate cells?
Basket cells synapse on the Purkinje cell body; Stellate cells synapse on the Purkinje cell dendrites
Granular cells send their axons into the molecular layer as ___ fibers.
Describe how information travels to the Purkinje cells.
Climbing fibers from the contralateral inferior olivary nucleus travel directly to the Purkinje cells. Mossy fibers from everywhere else travel through granular cells; these bifurcate into parallel fibers that run to the cerebellar cortex and Purkinje cells. Purkinje cells inhibit. deep nuclei
Describe the somatotopic maps of the cerebellum.
Vermal portion: trunk
Paravermal portion: limbs
Describe the input and output of the flocculonodular lobe.
Input: vestibular afferents-> Fastigial nucleus of cerebellum -> vestibular nuclei -> ascending MLF & Descending MLF, lateral vestibulospinal tract
Information travels from the medial hemisphere of the cerebellum to the ___ nucleus, then to the ___ nucleus, and finally through the ___ tract.
Globose-emboliform; red; rubrospinal tract; note the decussation from globose to red
Information travels from the lateral hemisphere of the cerebellum to the ___ nucleus, then to the ___, then to the cerebral cortex.
Dentate; ventrolateral thalamic
What are the 6 layers of the cortex?
I: molecular layer
II: external granular layer
III: external pyramidal layer
IV: internal granular layer
V: internal pyramidal layer
VI: polymorphic layer
What are the efferents and afferents of layers II and III?
Afferents: other cortical
What are the efferents and afferents of layer IV?
Efferent: Layer I
Afferent: Thalamic relay nuclei
What are the efferents and afferents of layer V?
Efferent: brainstem, SC, corticostriate
What are the efferents and afferents of layer VI?
Afferent: Intralaminar nuclei
How are layers IV and V seen on myelin stains?
IV: outer band of Baillarger
V: inner band of Baillarger
Describe pyramidal cells.
-Long apical dendrite and a basal dendrite
-Axons leave cortex (excitatory - glutamate)
Describe non-pyramidal cells.
-Interneurons of the cerebral cortex
-Axons don't leave cortex (inhibitory - GABA)
What is the distribution of pyramidal cells and non-pyramidal cells?
80% pyramidal, 20% non-pyramidal
What are the 4 parts of the corpus callosum and where are they located?
1. Genu (frontal)
2. Anterior body (frontal)
3. Posterior body (parietal)
4. Splenium (occipital and temporal)
What is the anterior commissure?
Interconnects temporal lobe and components of olfactory system
What are association bundles (fasciculi)?
Corticocortical connections in the same hemisphere; none are discrete point-to-point; fibers travel in both directions
What are primary neocortical areas?
Direct link to the world; inputs from thalamic nuclei, outputs to brainstem and SC
Where is the primary motor neocortical area?
Precentral gyrus (4)
Where is the primary somatosensory neocortical area?
Postcentral gyrus (312)
Where is the primary visual neocortical area?
Where is the primary auditory neocortical area?
Transverse temporal gyrus (41)
Where is the primary gustatory neocortical area?
Where is the primary vestibular neocortical area?
What are unimodal association areas?
More complex response functions; adjacent to primary cortical areas; less precise
Injury to unimodal association areas causes ___.
Where is the premotor unimodal association area and what does it do?
6; involves larger groups of muscles in an activity
Where is the supplementary motor association area and what does it do?
6; assumption of posture or using muscles on both sides of the body
Where is the somatosensory unimodal association area?
Where is the visual unimodal association area?
18, 19, others?
What are multimodal association areas?
Deal with high level intellectual functions; association areas send converging inputs here
Injury to multimodal association areas can cause ___ (motor) or ___ (sensory).
What are the three major multi-modal association areas?
1. Parieto-occipital-temporal region
2. Prefrontal area
3. Limbic area
Injury to the right inferior parietal lobule can cause ___ (ispilateral, contralateral) neglect.
Injury to the left parietal area can cause an ___.
The ___ prefrontal area is more important for working memory, attention, and logical aspects of problem solving. The ___ prefrontal area has extensive limbic connections and are more important for emotional aspects of planning and decisions.
All cortical areas receive corpus callosum commissural fibers except for three areas. What are they?
1. Hand area of somatosensory and motor cortex
2. Area 17
3. Temporal lobe (connections pass through anterior commissure)
What is the reticular formation?
Coordination network for the brainstem nuclei
What are some of the functions of the reticular formation?
1. Pattern generator (chewing, swallowing, coughing, etc.)
2. Centers for respiratory/cardiovascular/micturition control
What are the three main hypothalamic inputs?
1. Fornix (hippocampus)
2. Stria terminalis (amygdala)
3. Medial forebrain bundle (amygdala)
What are the four main hypothalamic outputs?
3. Spinal cord
The ___ function in recollective memory and may also aid in spatial memory.
What are the two groups of fiber projections from the mammillary bodies?
1. Mammillothalamic tract (to anterior thalamic nucleus)
2. Mamillotegmental tract (to midbrain tegmentum)
Describe the Papez circuit, which describes the limbic system.
Main circuit: Cingulate gyrus -> Hippocampus -> Mammillary body of hypothalamus -> Anterior nucleus of thalamus -> Cingulate gyrus
*See powerpoint picture
Direct release of hormones occurs via the ___ pituitary, or neurohypophysis. Indirect release of hormones occurs via the ___ pituitary, or adenohypophysis.
Biologic rhythms are characterized by what four factors?
1. Period (time to complete one full cycle)
2. Frequency (# cycles/time unit)
3. Phase (point of reference from a standard/average value)
4. Amplitude (magnitude of variation from mean)
What are the four types of biologic rhythms?
The medial nuclei of the amygdala are interconnected with the ___ system.
The central nuclei of the amygdala are interconnected with the ___ and related brainstem nuclei; important in emotional responses.
The basolateral nuclei are extensively interconnected with ___ areas.
What are the inputs to the amygdala?
Olfactory information (from bulb and cortex) arrives at the medial nuclei; thalamic and unimodal association area information reaches the basolateral nuclei. Visceral sensory inputs reach the central nuclei from the hypothalamus and brainstem.
Fibers leave the amygdala through the ___ and ___.
Stria terminalis; ventral amygdalofugal pathway
Outputs from the amygdala include the following: ...
Unimodal sensory cortex, anterior limbic cortex, ventral striatum, thalamus (dorsomedial nucleus), hypothalamus, brainstem visceral nuclei, hippocampus
What causes Kluver-Bucy syndrome?
Bilaateral lesions to the tips of the temporal lobes
What are the 5 symptoms of Kluver-Bucy?
2. Dietary changes/hyperphagia
5. Visual agnosia
What are the components of the hippocampus?
1. Dentate gyrus
2. Hippocampus proper
What is the major interface between the hippocampus and vast areas of the association cortex?
Bilateral damage to the hippocampus causes ___.
What are the major inputs to the hippocampus?
Unimodal, multimodal, and limbic cortical areas; septal nuclei (backward through fornix), amygdala