The Basal Ganglion

THE BASAL GANGLIA CONSISTS OF z z z z z

CAUDATE NUCLEUS PUTAMEN GLOBUS PALLIDUS SUBTHALAMIC NUCLEUS SUBSTANTIA NIGRA

CORPUS STRIATUM Caudate nucleus and Putamen are together called corpus striatum. Putamen, Globus pallidus are together called lenticular nucleus. FUNCTIONS z z z z z z z

Basal ganglia discharge begins before movement. Involved in planning and programming of voluntary movements. Inhibits the muscle tone. Regulates the subconscious gross movements in muscles. Role in cognitive processes– caudate nucleus. Substantia nigra is involved in coordination of impulses essential fro skilled movements. Center for control of normal automatic movements like swinging of arms during walking.

APPLIED: PARKINSON’S DISEASE. Case degeneratiuon of substantia nigra and globus pallidus. FEATURES CHARACTERISTIC z Rigidity z Posture in flexed attitude z Due to lack of dopaminergic activity, due to degeneration of substantia nigra.

z z

z

Resting tremors Hypokinesia- difficulty in initiating voluntary movements. Slow speech, mask life face, shuffling gait, loss of movement during walking such as swinging of arms.

CHOREA: Spontaneous involuntary movements due to damage to the caudate nucleus. FEATURES: z Muscle weakness z Rapid, irregular, involuntary movements ATHETOSIS Due to lesion of lenticular nucleus FEATURES Continous slow, twisting movements WILSON’S DISEASE Copper content of substantia nigra is increased FEATURES Cirrhosis of liver Muscular rigidity Tremors Emotional problems CONNECTIONS: AFFERENT CONNECTIONS CORTICOSTRIATE THALAMOSTRIATE EXCITATORY(CHOLINERGIC) PROJECTIONSFIBRES AFFERENTS FROM CEREBRAL CORTEX. INTERNUCLEAR DOPAMINERGICN GABBA-ergic CONNECTIONS IGROSTRIATAL INHIBITORY TRACTS PROJECTIONS. EFFRENT CONNECTIONS.

NOTE: Projections from globus pallidus and substantia nigra to the thalamus are inhibitory. Multiple Choice Questions: 1. Basal ganglia consists of all except a) Caudate nucleus b) Red nucleus c) Globus pallidus d) Putamen

2. Function of basal ganglia a) Involved in planning of voluntary movements b) Inhibits the muscle tone c) Discharge begins before the movement d) All of the above

3. In Parkinson's disease, there is degeneration of a) Substantia nigra b) Caudate nucleus c) Putamen d) Subthalamic nucleus

4. Characteristic features of Parkinson's disease are all except a) Rigidity b) Flaccidity c) Flexed posture d) Resting tremors

5. Which of the following is true about chorea a) Results due to lesion of caudate nucleus b) Muscle weakness c) Spontaneous involuntary movement d) All of the above