Basal ganglia, their connections and functions, Parkinsonism
Basal ganglia: a group of structures in the brain that help control movement. They play an important role in making sure our movements are smooth and coordinated. These structures work together to plan and execute voluntary actions like walking, talking, or picking up objects.[edit | edit source]
The Basal Ganglia are composed of multiple important structures: Caudate Nucleus, Putamen, Globus Pallidus (Internus & Externus), Subthalamic nucleus, Substantia Nigra. These components anatomy will be discussed in detail below.
Caudate Nucleus: a C-shaped structure deep in the brain which surrounds the lateral ventricles. It extends from the front to the back, so it is visible in mostly all coronal brain slices. It is one part of the STRIATUM- composed of the Caudate Nucleus and the Putamen.
Putamen: a round, oval-shaped structure located lateral to the caudate nucleus and is separated from it by a bundle of nerve fibers called the INTERNAL CAPSULE (is specified in drawing above, to showcase the region we can find the capsule, but the fibers are running not just between the 2 components, but rather conveying motor and sensory information to and from the cortex)
Globus Pallidus Internus & Externus: located medially to the putamen, next to the thalamus. The internus is located more medially whilst the externus is located more laterally (closer to the putamen). The INTERNUS is responsible for OUTPUT, sending signals to the thalamus and influencing motor control. On the other hand, EXTERNUS is responsible for INPUT, receiving information from neurotransmitters which affects the output from the internus and subsequent reactions.
Subthalamic Nucleus: from the name, located under the thalamus. Also located above the brainstem. It is involved in motor control by having an influence on the GLOBUS PALLIDUS.
Substantia Nigra: Located beneath the thalamus in a similar region to the subthalamic nucleus, but is easily distinguishable by the black color special to this one component of the basal ganglia. It is consisting of 2 parts: pars compacta & pars reticulata. The pars compacta is the darker stained region responsible for producing DOPAMINE, which is important in the function of some specific pathways in the basal ganglia. The pars reticulata is lightly stained and is responsible for sending signals involved in modulating the activity of other basal ganglia structures.
