Block Three

medicoblasto's version from 2016-07-13 23:26

Basal ganglia

Question Answer
Basal ganglia Translates the idea of movement into the motor expression of that idea.
Direct pathwayDisinhibits thalamic motor nuclei (VA and VL), resulting in cortical activation and movement initiation.
Indirect pathway Inhibits the VA and VL, resulting in reduction in cortical activation and movement suppression.
DyskinesiaMovement disorders
HyperkinesiaInvoluntary spontaneous movements
HypokinesiaLack of spontaneous movement, and slowing of voluntary movement.
AthetosisContinual uncontrolled writhing movements (disappear during sleep).
ChoreaA series of rapid, jerky, involuntary movements.
DystoniaExtreme contraction of antagonist muscle groups results in limbs locked in one position for long periods of time.


Question Answer
DystoniaA severe form of athetosis.
BallismusInvoluntary flinging of limbs.
BradykinesiaPoverty and slowness of movement.
TremorOnly seen while extremity is at rest; disappears during sleep.
RigidityResistance to passive limb movements. (Lead pipe rigidity).
Cogwheel rigidityTremor and rigidity.

Basal ganglia breaks down as follows:

Neurological StructureBasal Nucleus
Caudate nucleusCaudate nucleus
Lentiform nucleusGlobus pallidus + Putamen
Corpus striatumLentiform + Caudate
Neostriatum (striatum)Caudate + Putamen
Amygdaloid bodyAmygdaloid nucleus

Clinical Summary

Lesion toResult
Globus pallidusTourettes
Subthalamic nucleusBallismus
Substantia nigra Parkinson’s
Various structuresWilson’s
Damage during pregnancyCerebral palsy

Connections of the Basal ganglia

Afferent Pathways

Question Answer
Cortex to striatumCorticostriatal
SNpc to various BG structures.Nigrostriatal
Amygdala to ventromedial caudate and putamen.Amygdalostriatal
From centromedian (and other) thalamic nuclei to striatum.Thalamostriatal

Efferent Pathways

Question Answer
From striatum (caudate and putamen) to globus pallidus.Striatopallidal
From striatum to substantia nigra.Striatonigral
Globus pallidus to thalamus.Ansa lenticularis
Globus pallidus to subthalamus.Fasciculus lenticularis