Introduction[edit | edit source]
The substantia nigra (SN) is a midbrain dopaminergic nucleus which has a critical role in modulating motor movement and reward functions as part of the basal ganglia circuitry. It is one of the brainstem nuclei and part of the extrapyramidal system. Although it is often referred to as one structure, there are actually two substantia nigrae, one on each side of the brainstem. They are situated in the anterior midbrain and mark the transition point of the tegmentum and cerebral peduncles.
Function[edit | edit source]
Located within the midbrain posterior to the crus cerebri fibers of the cerebral peduncle, the substantia nigra can be functionally and morphologically divided into two regions,
- Pars compacta (SNpc): Most of the dopamine neurones of the brain are found in either the substantia nigra or the ventral tegmental area, which is located adjacent to the substantia nigra. The dopamine neurones in. the SNpc express high levels of a pigment called neuromelanin, which accounts for their dark colour.
- Pars reticulata (SNpr) with populated largely by GABA neurones.
The SN It is an important relay station in the motor system. Projections from the substantia nigra leave the the forebrain forming synapses on multiple neuronal populations throughout the basal ganglia including the
- Caudate nucleus
- Anterior cerebral cortex
- Precentral cortex.
The substantia nigra is classically considered to be the primary input into the basal ganglia circuitry and a critical element to these functions ie functions ranging from voluntary movement, cognitive planning, emotions and reward functions, and even cognition and learning.
Physiotherapy Implications[edit | edit source]
The influence of the substantia nigra on movement is made apparent by observing the symptoms of Parkinson's disease, which are associated with the death of dopamine neurones in the substantia nigra pars compacta.
Being one of the major dopamine-producing areas of the brain the substantia nigra has functions other than motor control. It is also thought to play important roles in a number of other functions and behaviors, including learning, drug addiction, and emotion.
References[edit | edit source]
- Sonne J, Reddy V, Beato MR. Neuroanatomy, substantia nigra.2019 Available:https://www.ncbi.nlm.nih.gov/books/NBK536995/ (accessed 24.4.2022)
- Neuroscientifically challenged Substantia Nigra https://neuroscientificallychallenged.com/posts/know-your-brain-substantia-nigra (accessed 24.4.2022)
- Radiopedia Substantia Nigra Available;https://radiopaedia.org/articles/substantia-nigra (accessed 24.4.2022)