Putamen

Location and borders

Putamen (putamen) is located deep within the white matter of the telencephalon and is connected to adjacent structures of the diencephalon and telencephalon:

• Globus pallidus (globus pallidus) is located medially to the putamen. The putamen covers it like an eggshell and extends beyond it in the rostral and caudal directions. The putamen and globus pallidus form the lenticular nucleus (nucleus lentiformis), in which the putamen is the outer part. They are separated by a thin band of white matter, the medial medullary lamina (lamina medullaris medialis).
• Internal capsule (capsula interna) is a massive layer of projection fibers. Its anterior limb separates the head of the caudate nucleus and the putamen.
• External capsule (capsula externa) separates the putamen from the claustrum (claustrum), a thin sheet of gray matter lying lateral to the putamen.
• Thalamus (thalamus) is a large mass of gray matter located medial to the putamen and internal capsule.

Structure and phylogenesis

During embryogenesis, the putamen develops from the ganglionic eminence, a derivative of the ventral part of the telencephalic vesicle.

• Corpus striatum / striatum (corpus striatum) is the anatomical combination of the putamen and the caudate nucleus (nucleus caudatus). These nuclei are interconnected by numerous thin bridges of gray matter. The striated appearance forms during embryogenesis when fibers of the internal capsule grow through the initially homogenous basal ganglia.
• Neostriatum is a phylogenetically younger part of the basal ganglia, which includes the putamen and the caudate nucleus. During evolution, the neostriatum enlarged with the development of the cerebral cortex and reaches its maximum development in higher mammals and humans.

Neural connections and pathways

The putamen contains D1 and D2 dopamine receptors.

• Afferent pathways: The putamen receives excitatory signals from the frontal cortex; the neurotransmitter is glutamate. Modulating signals arrive via the nigrostriatal pathway from the substantia nigra; the neurotransmitter is dopamine.
• Efferent pathways: Inhibitory pathways from the D1 receptor zone project to the internal segment of the globus pallidus; the neurotransmitter is GABA. Inhibitory pathways from the D2 receptor zone project to the external segment of the globus pallidus; the neurotransmitter is GABA.

Functions and clinical significance

The putamen, as part of the striopallidal system, participates in the regulatory loop of interactions between the cortex and the basal ganglia.

• Functions: The basal ganglia are capable of exciting or inhibiting motor areas of the cortex. They participate in the initiation and coordination of movements, regulation of muscle tone, and control of complex motor patterns and automated movements.
• Pathology: Lesions of the basal ganglia are considered together with damage to functionally related nuclei, including the substantia nigra and subthalamic nucleus. They lead to an excess or deficit of motor impulses and pathological alterations in muscle tone. The most frequent cause of basal ganglia damage is Parkinson's disease, the clinical triad of which includes rigidity, akinesia, and tremor.

Not to be confused with: eggshell

In biology and embryology, the term "shell" (putamen/eggshell) is also used to refer to the calcareous outer covering of eggs in birds and reptiles. This complex system of membranes develops as an adaptation to terrestrial development, protects against desiccation and mechanical damage, and ensures gas exchange.

Class and exam questions

What else to study on this topic

• Globus pallidus
• Caudate nucleus
• Substantia nigra
• Extrapyramidal system

Other topics in the "Anatomical Structures" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.