ine fibers. These fibers originate in the cerebral cortex (within the temporal lobe) and run posterolateral. From the sublenticular limb of the internal capsule, these fibers join the crus cerebri and terminate in the pons.
The crus cerebri connects the cerebral hemispheres to the cerebellum through a network of neurons. These neurons are mostly the white matter (axons covered in myelin sheaths) of motor neurons.
The crus cerebri is critical for transporting nerve impulses from the brain, down the spinal cord, and eventually to the relevant muscles.
The Substantia Nigra Purpose, Function, And Structure
Together the anterior pars reticulata and the posterior pars compacta from the substantia nigra, a collection of pigmented nuclei. The substantia nigra separates the crus cerebri from the tegmentum.
- Due to the presence of melanin, the pars compacta provides the region with dark pigmentation. The cells in this area produce/synthesize dopamine.
These cells mediate movement and motor coordination (usually inhibiting neurons, particularly those in the caudate nucleus and putamen).
- Cells in the pars reticulata receive impulses from the pars compacta and push the impulses along to the thalamus. This region is important for eye movements, thinking, and learning.
These cells also have an inhibitory action through the gamma-aminobutyric acid present in their cells.
This inhibitory effect prevents/blocks impulses from your brain from reaching the muscles.
The pars compacta and reticulata (together with the globus pallidus) create the striatum.
The substantia nigra plays a fundamental role in assisting with movement, facilitating connections in the brain (as part of the basal ganglia), and controlling various chemical components (e.g., dopamine).
The Tegmentum Purpose, Function, And Structure
Separated from the crus cerebri by the substantia nigra and located in the posterior region of the midbrain (but still anterior to the tectum), the tegmentum continues down through the pons and up through the midline.
The tegmentum consists of fiber tracts and two differentiated color areas:
- The red nucleus assists in movement and the coordination of sensorimotor information (where sensory information is synergized/integrated with motor responses and affects voluntary and reflexive actions).
Nerve fibers (crossed fibers) from the cerebellar peduncle surround and (some) terminate in the red nucleus. These fibers receive information from the motor cortex.
- Periaqueductal gray matter. Behavioral (like pain and stress) processing and responses occur in this midbrain region. This region receives its color from the lack of axons (i.e., the greater concentration of neuron bodies).
This region deals with pain suppression through endorphin production.
Although some sources view the substantia nigra as part of the tegmentum, others view it as a separate structure in the midbrain.
The tegmentum is essential for alertness, movement, and processing of pain.
Complications Of The Cerebral Peduncles
As with most brain regions, the cerebral peduncles are not exempt from experiencing injury and diseases. When negatively affected by these complications, the cerebral peduncles severely impact the organism’s ability to function correctly.
Some complications include:
- A lack of proprioception.
- Loss of balance.
- Unrefined motor skills.
- Various degrees of paralysis.
Trauma is a significant cause of complications of cerebral peduncles. When the cerebral peduncles are injured, the symptoms present in the corresponding body part (i.e., the part of the body that the damaged nerve cells connect to).
Diseases And Conditions Affecting The Cerebral Peduncles
Aside from trauma, diseases are the other significant reason for complications in the cerebral peduncles.
Some of these diseases include:
Bilateral Cerebral Peduncle Infarction
An infraction is when blood vessels leading to a particular organ (or part thereof) become blocked (often through swelling). This blockage leads to the “starvation” of cells in the affected area, which begin to die.
During a study in 20