💢 فسيو العصبي motor 7
#Physiology_of_CNS 17
#CNS
*⃣Basal ganglia—control of movement :
🔹consists of the striatum, globus pallidus, subthalamic nuclei, and substantia nigra.
🔹modulates thalamic outflow to the motor cortex to plan and execute smooth movements.
🔹Many synaptic connections are inhibitory and use GABA as their neurotransmitter.
🔹The striatum communicates with the thalamus and the cerebral cortex by two opposing pathways.
🔹Indirect pathway is, overall, inhibitory.
🔹Direct pathway is, overall, excitatory.
🔹Connections between the striatum and the substantia nigra use dopamine as their
neurotransmitter. Dopamine is inhibitory on the indirect pathway (D2 receptors) and
excitatory on the direct pathway (D1 receptors). Thus, the action of dopamine is, overall,
excitatory.
🛑Lesions of the basal ganglia include :👇👇👇
1⃣Lesions of the globus pallidus:👇
■ result in inability to maintain postural support.
2⃣Lesions of the subthalamic nucleus:👇👇👇
■ are caused by the release of inhibition on the contralateral side.
■ result in wild, flinging movements (e.g., hemiballismus).
3⃣Lesions of the striatum:👇
■ are caused by the release of inhibition.
■ result in quick, continuous, and uncontrollable movements.
■ occur in patients with Huntington disease.
4⃣Lesions of the substantia nigra:👇
■ are caused by destruction of dopaminergic neurons.
■ occur in patients with Parkinson disease.
■ Since dopamine inhibits the indirect (inhibitory) pathway and excites the direct (excitatory) pathway, destruction of dopaminergic neurons is, overall, inhibitory.
■ Symptoms include lead-pipe rigidity, tremor, and reduced voluntary movement.
#⃣Remember that :👇👇👇
🔷Premotor cortex and supplementary motor cortex (area 6) 👌 and 👇
🔷Primary motor cortex (area 4 )
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