Globus pallidus

The globus pallidus (of the Latin , pale sphere ) indicates a structure Sous-cortical E of the Cerveau pertaining to the system of the Ganglions of the base. The globus pallidus form the dorsal part of the Pallidum and takes part with the Striatum and the Substantia will nigra with a circuit striato-pallido-nigral which constitutes the heart of the Système of the ganglia of the base of the primate.

Anatomy

At the Primate, the globus pallidus (GP), is divided by a fine plate of white substance into two parts side (known as external segment , noted GPe) and the other median ( segment interns , GPI). Each part is thin in dimension mediolatérale and extended in dimensions postéroantérieure and inferosupérieure. The internal segment is in contact with the knee of the internal Capsule.

The neuronal populations of these two segments are similar. Their dendritic arborisations are of great dimension but almost punts, discoidal. They are parallel the ones with the others and compared to the side edge of the pallidum.

In the field of the Phylogenetic evolution , the globus pallidus is the oldest structure of the ganglia of the base. Division between GPe and GPI is specific to the primate and at the others Mammifère S does not exist which have a unit globus pallidus. At the Bird X, following the Forum on the nomenclature of the avian brain, the Noyau entopédunculaire was famous globus pallidus by homology with the others Vertébré S.

The GP shares many histological characteristics with the Substantia will nigra (leave lateralis and leave reticulata) and, just like the latter, it receives many axons of striatum.

Connections

The GP receives axons of the thorny neurons of the Striatum. These afférences are inhibiting and especially directed towards GPe which itself projects on GPI forming what DeLong baptized the indirect Voie of motricity.

GPe maintains also a great number of reciprocal connections with the Noyau under-thalamique.

GPI constitutes the principal exit point of the pallidum and overall of the ganglia of the base (with the Substantia will nigra leave reticulata). He exerts an inhibiting action on the Thalamus and the cerebral Tronc, via the extra-pyramidal Système.

Function

The GP belongs to the subcortical nervous circuits implied in particular in the Motricité, and in particular on the control of the Posture. But it also takes part in nondriving functions (Cognition, emotion S, etc).

External bonds

Functional anatomy off movement disorders, A.R. Crossman, Newspaper off Anatomy , Volume 196 Page 519 - May 2000

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