Lab 11: Basal Ganglia System Flashcards
Overview of the Basal Ganglia
-as a group, these nuclei influence the selection and initiation of voluntary motor activity, primarily via influence on the frontal cortex.
their connections include:
A: motor areas of cortex—Striatum—-globus pallidus—-thalamus—-motor, premotor and supplementary motor cortex
B: globus pallidus—-subthalamic nucleus—–globus Pallidus, etc.
C: substantia nigra (pars compacta)—striatum
-They also function, through their influence on the frontal lobe, in some aspects of motivation, emotion and cognition
Caudate Nucleus
Head: rostral expanded portion, lateral to the anterior horn of the lateral ventricle
Body: long part lateral to the body and atrium of the lateral ventricle
Tail: along the roof of the inferior horn of the lateral ventricle
Caudate Nucleus Structure
A C-shaped structure with an expanded rostral extremity, the head which decreases in size to form a body and a tail. The head of the caudate nucleus bulges into the anterior horn of the lateral ventricle. The head and body have a close relationship to the lateral wall of the anterior horn and body of the lateral ventricle respectively, while the tail of the caudate nucleus is situated in the roof of the inferior horn of the lateral ventricle.
Putamen Location
The putamen is lateral to the globus pallidus.
-the anterior limb of the internal capsule separates the lentiform nucleus (Putamen and globus pallidus) from the head of the caudate nucleus. Rostrally, the head of the caudate nucleus and the putamen are connected by cellular bridges and both become continuous rostroventrally
Posterior Limb of the Internal Capsule Separates What 2 structure?
The thalamus and the lentiform nucleus
Nucleus Accumbens
A component of the limbic part of the basal ganglia
Anterior Limb of the Internal Capsule Separates what 2 structures?
The head of caudate and putamen
Striatum
Consists of input nuclei (caudate and putamen) of the basal ganglia, receiving impulses from widespread areas of the cerebral cortex via corticostriate fibers
Genu of the Internal Capsule
Area of internal capsule that is adjacent to the interventricular foramen
Insular cortex
Covers lentiform nucleus at the level of the posterior limb of the internal capsule
Globus Pallidus (external/lateral Segment)
An intrinsic nucleus that has output to the subthalamic nucleus
Globus Pallidus (internal/medial segment)
An output nucleus,with important outflow to the thalamus
Skeletomotor Loop
Cortex——putamen—–medial segment (GP)——VL of thalamus—–supplementary motor cortex
Thalamus
Receives fibers from thalamic fasciculus
- VL nucleus belongs to the somatomotor system
- Dorsomedial nucleus is important for the relay of information to association and limbic areas of the frontal cortex
Subthalamic Nucleus
Medial to the internal capsule
- is an intrinsic nucleus of the basal ganglia complex
- has input from the external (lateral) segment of globus pallidus and outflow to the internal (medial) segment of the Globus pallidus, with these connections traveling via the subthalamic fasciculus
Substantia Nigra
Dorsal to the basis pedunculi in the midbrain
- is a nucleus of the basal ganglia complex
- includes an output Nucleus, the pars reticulata, that receives input from the striatum and that sends fibers to the thalamus as part of the oculomotor loop
- has an INTRINSIC nucleus, the pars compacta, that sends dopaminergic fibers to the striatum via the nigrostriatal pathway
Tail of the Caudate
Dorsal to the temporal horn of the lateral ventricle
Posterior Limb of the Internal capsule (in regards to basal ganglia circuitry)
-contains fibers from VA/VL to the cerebral cortex
Supplementary Motor Cortex
Main target of the basal ganglia
Prefrontal Cortex
Most of the frontal cortex that is rostral to the motor areas (premotor and primary motor cortex, supplementary motor cortex, frontal Eye field)
Frontal Eye Field
-immediately rostral to the premotor cortex
Tremor (fine oscillations)
Often at rest
Athetosis
Slow, writhing movements of limbs, usually distal muscles
Chorea
Rapid, flick-like movements of distal limbs and/or face
Ballismus
Violent movements, mainly of proximal muscles
Rigidity
Resistance to passive movement
Bradykinesia
Slowness in movement
