Basal Ganglion

What are the components of the basal ganglion that are found in the cortex?

caudate

putamen

globus pallidum

What structure is located between the globes pallid us and the external capsule?

putamen

What structure is located between the putamen and internal capsule?

globus pallidus

neostriatum

caudate and putamen

Which components of the basal ganglia are NOT found in the cortex?

sub thalamic nucleus

substantia nigra

Which component of the basal ganglia is located lateral to the hypothalamus?

sub thalamic nucleus

What components make up the subthalamus

zona incerta

preubral field

sub thalamic nuclei

Where is the substantia nigra located?

tegmentum of mesencephalon

zona compacta

located dorsally in the substantia nigra, closest to red nucleus

contains melanin

zona reticulares

located ventrally in the substantia nigra, closest to the crus cerebri

corpus striatum

caudate, putamen, globus pallidus

What is the primary input in the the basal ganglion?

from cerebral cortex into striatum

What are the three inputs into the basal ganglion?

1. primary input is from cerebral cortex into striatum

2. thalamus into striatum

3. motor and premotor cortex into sub thalamic nucleus

What are the interconnections between the basal ganglion?

1. reciprocal connections between striatum and substantial nigra: striatonigra mostly into reticulates, nigrostraital tracts mostly from compacta

2. reciprocral connections between palladium and sub thalamic nucleus: pallidosubthalamic from lateral pallidum, sub thalamicpallidal into medial pallidum

3. numerous striatopallidal projections

What is the major output form basal ganglion?

pallidum to thalamus

What are the outputs from basal ganglion?

1. pallidum to thalamus

2. pallidothalamic via two bundles: lenticular fasciculus, anda lenticulares

3. thalamus then projects to premotor cortex

4. small output from substantial nigra to thalamus

What are the functions of the basal ganglion?

association areas of cortex generate will to move

striatum stores movement programs

association cortex activates striatum

basal ganglion initiates movement via pallidum to anterior ventral thalamus to premotor cortex to motor cortex

positive signs

actions the patient does not want to happen but cannot prevent

negative signs

actions the patient wants to occur but won't

What are the negative signs of basal ganglion disease?

akinesia: hesitancy in starting a movement

bradykinesia: slowness of speed of movement execution

abnormal postural adjustments: head and neck flexion and inability to make postural adjustments when falling, tilting, standing

What are the positive signs of basal ganglion disease?

hypertonicity: in severe form can affect flexors and extensors to joint becomes bidirectional rigid, lead pipe rigidity

dyskinesia/hyperkinesia: tremors, chorea, athetosis, ballismus

*all dyskinesias occur at rest

tremors

rhythmical/oscillatory movements of distal limb/hand

chorea

rapid jerky movement in distal limbs and face

athetosis

slow, writhing, snakelike movements of limbs

ballismus

violent flinging of limbs d/t contraction of proximal muscles

Cog-wheel rigidity

Motor dysfunction secondary to a lesion of the basal ganglia in which the muscles respond in a jerky motion when force is applied during flexion of a joint, common symptom of Parkinson's disease

What are the presentations of Parkinson's Disease?

1. akinesia and bradykinesia

2. flexion of trunk, shuffles feet, does not swing arms

3. mask like facial appearance

4. handwriting gets small

5. speech becomes a whisper

6. paradoxical tremor of thumb and fingers, pill rolling

What is the mechanism of Parkinson's disease?

degeneration of dopaminergic neurons in substantial nigra

What are the treatments for Parkinson's disease?

levodopa

transplantation of fetal dopamine producing tissue

bilateral ablation fo medial pallidus

stimulatory electrodes in anterior ventral thalamus

What is the etiology of Huntington's disease?

autosomal dominant disease causing degeneration of striatal neurons

What are the presentations of Huntington's disease?

dyskinesia: chorea or athetosis or choreoathetosis

progressive dementia

What re the lesions of sub thalamic nuclei typically due to?

ischemia

How do lesions to the sub thalamic nuclei present?

hemiballismus

tardive dyskinesia

involuntary movements of the facial muscles, tongue, and limbs; a possible neurotoxic side effect of long-term use of antipsychotic drugs that target certain dopamine receptors (thorazine)

cerebral palsy

non progressive neonatal CNS disorder of the motor system most commonly caused by hypoxemia

involves pyramidal tract and basal ganglion and therefore presents as spasticity and dyskinesia