Extrapyramidal System (handout based) Flashcards
Pyramidal tracts refers to
the corticospinal and corticobulbar tracts
pyramidal system refers to
Motor system
Pyramidal tracts, strictly speaking refers to tracts that course longitudinally in
the pyramids of the medulla oblongata
These tracts subservethe automatic, static, postural and other less modifiable motor activities
Extrapyramidal tract
Specifically the tracts that does not pass through the pyramid of the medulla oblongata. The corticorubrospinal, corticoreticulospinal, , corticovestibulospinal, and corticotectospinal
Extrapyramidal tract
rigidity and tremor without loss of voluntary movement
Akinesia
Basal ganglia is composed of
Caudate nucleus, lentiform nucleus, Subthalamic nucleus (nucleus of Luys) & Substantia nigra
Is the RECEPTIVE PART of the basal ganlia, receiving topographically organized fibers from all parts of the cerebral cortex and from the pars compacta of the substantia nigra
Striatum (mainly the Putamen)
are the OUTPUT nuclei of the basal ganglia
Palligum medial (interna) & substantia nigra pars reticulata
Nuerotransmitters used in direct pathway
Glutamate & dopamine
Neurotransmitters used in indirect pathway
Gamma amino butyric acid (GABA) & enkephalin
Stimulation of the _______________ inhibits the ________ pallidum, which in turn, disinhibit the _______________ nuclei of the thalamus. As a consequence, thalamocortical drive is enhanced and cortically initiated movements are facilitated
Direct pathway; medial; ventrolateral and ventroanterior
The ______________ Has striatal projection that inhibits the _________ pallidum which in turn disinhibit the ___________ nucleus providing excessive subthalamic drive to the medial pallidumcausing a net effect of thalamic inhibition and reduced thalamocortical input
Indirect pathway; lateral; subthalamic
enhanced conduction through the indirect pathway leads to
hypokinesia
enhanced conduction through the direct pathway results in
hyperkinesia
sweeps around the internal capsule
Ansa lenticularis
traverses the internal capsule
Fasciculus lenticularis
Pre pyramidal circuit
Cerebral Cortex ➡️ Striatum ➡️ Globus Pallidus ➡️ thalamus ➡️ Pre Motor or Supplemental motor cortex ➡️ PRIMARY MOTOR CORTEX
function as a kind of clearinghouse where intended activities are facilitated and unnecessary ones are suppressed (DennyBrown & Yanagisawa)
Basal ganglia
Negative symptoms of basal ganglia disease
bradykinesia, hypo or akinesia and loss of normal postural reflexes
Positive symptoms of basal ganglia disease
Chorea, athetosis, ballismus and dystonia
disinclination on the part of the patient to use an affected part and to engaeit freelin all the natural actions of the body
Hypokinesia and akinesia
slowness rather than lack of movement
Bradykinesia
passive movement is not preceded by a “free interval”, there is uniform quality throughout movement, when released, does not go back to original position
Rigidity
Affect both flexor and extensor muscles, but more prominent on flexors
Rigidity
altered muscle tone where the muscles are continuously or intermittently firm and tense. The is a low threshold for involuntary sustained muscle contraction
Rigidity
Characterized by brief, semi-directed, irregular movements that are not repetitive or rhythmic, but appear to flow from one muscle to the next
Chorea
slow, involuntary, convoluted, writhing movements of the fingers, hands, toes, and feet and in some cases, arms, legs, neck and tongue
Athetosis
Caused by lesions to the striatum
Athetosis
Due to decrease in activity of thesubthalamic nucleusof thebasal ganglia, resulting in decreased suppression of undesired movements
Ballismus
Repetitive, but constantly varying, large amplitude involuntary movements of the proximal parts of the limbs.
Ballismus
This activity is almost ceaseless and movements are often complex and combined
Ballismus
Sustained muscle contractions cause twisting and repetitive movements or abnormal postures, produced by cocontractionof agonist and antagonist muscles in one region of the body
Dystonia
Responsible for: the regulation of muscle tone, coordination of movements, control of posture and gait
Cerebellum
Receives special proprioceptive impulses from the vestibular nuclei (vestibulocerebellum)
Floculonodular lobe of cerebellum
Essentially concerned with equilibrum
Floculonodular lobe of cerebellum
Receive proprioception from muscles and tendons of the limbs (spinocerebellum)
Anterior lobe of cerebellum (paleocerebellum)
Derives its afferent fibers from the cerbralcortex via the pontine nuclei (Pontocerebellum)
Posterior lobe of cerebellum (neocerebellum)
Coordinates the movements of the eyes and body with respect to gravity and movement of the head in space
Vermian zone of cerebellum
Interruption of connections disturb the posture, tone, locomotion and equilibrum
Vermian zone of cerebellum
Receive peripheral and central projection, influencing postural tone and individual movements of the ipsilateral limbs
Paravermian/ intermediate zone of cerebellum
Concerned mainly with coordination of movements of ipislateral limbs
Lateral zone of cerebellum
Cells from the vermis project in what deep cerebellar nuclei?
Fastigial
Intermediate zone project in what deep cerebellar nuclei?
Globose and Emboliform
Lateral zone project in what deep cerebellar nuclei?
Dentate
receives information from the premotor and supplementary motor cortices via the pontocerebellar system; helps initiate volitional/ voluntary movements
Dentate nucleus
receives pontocerebellar and spinocerebellar fibers ; It fires in relation to a movement once it has started
Interpositus Nucleus
controls antigravity and other muscles synergies in standing and walking
Fastigial nucleus
