s) throughout the body.
- Temporo-parieto-occipito-pontine fibers (starting in the temporal lobe; these fibers connect the pons with the occipital, parietal, and temporal cortices).
As with all parts of the human body, the cerebral peduncles are critical for the organism’s effective functioning.
The Cerebral Peduncles Location And Structure
The cerebral peduncles are located in the midbrain’s anterior (towards the front) regionhttps://radiopaedia.org/articles/cerebral-peduncles. The posterior tectum, together with the cerebral peduncles, form the midbrain.
The midbrain forms the topmost spinal cord region and connects the forebrain (via the thalami) to the cerebellum and pons.
The cerebral peduncles “branch off,” connecting to either side of the brain and leaving a gap between the two stalks. We refer to this separation as the interpeduncular cistern (a chamber filled with cerebrospinal fluid).
The cerebral peduncles are subdivided into the crus cerebri and the tegmentum (in the posterior). This division is by the substantia nigra.
The cerebral peduncles are mostly white matter tracts. However, the composition of the cerebral peduncles changes along their length (divided into two parts adjacent to the inferior colliculus and the superior colliculus).
Within the inferior colliculus region, we find:
- Crus cerebri (containing four fiber tracts).
- Substantia nigra (made up of the pars reticulata (anterior) and pars compacta (posterior)).
- Tegmentum (which extends into the midline while the crus cerebri terminates).
- Decussation of the superior cerebellar peduncles (where fibers crisscross over the midline).
- Cerebral aqueduct.
- Lemnisci (medial, spinal, trigeminal, and lateral lemniscus).
- Trochlear nuclei.
In addition to the above, within the superior colliculus region of the cerebral peduncle, we find:
- Red nuclei
- Oculomotor nuclei
What Is The Cerebral Peduncles Purpose?
The cerebral peduncles play a critical role in passing information (nerve impulses) between the various parts of the brain (the forebrain and the cerebellum) and the spinal cord to other parts of the central nervous system.
However, the function of the cerebral peduncles is not limited to “passing on” information. They also play a role in “refining” the instructions passed on from the cerebral cortex.
Once the higher regions of the brain decide on the best course of action, the information moves into the cerebral peduncles. Here, the peduncles “adjust” the instructions to fit the situation.
I.e., nerve impulses emitted by the cortex fail to factor in certain aspects, like where the limbs are, how the body is already moving, etc. The cerebral peduncles receive this information from the other brain regions and adjust the nerve impulses accordingly.
If the instructions were not tailored to fit the need, our responses would be exaggerated, insufficient, and ungainly.
The cerebral peduncles also assist in learning new motor skills and maintaining balance and posture through interpreting proprioceptive stimuli.
The cerebral peduncles are a product of their various components. Each component is responsible for different functions and information processing; some of these include:
The Crus Cerebri Purpose, Function, And Structure
The two horns of the cerebral peduncles (located in the midbrain’s anterolateral regions) are separated from the tegmentum by the substantia nigra.
The crus cerebri contains four fiber tracts:
- Frontopontine fibers. These fibers, located most medially, originate in the frontal lobe and terminate at the pontine nuclei.
- Corticospinal fibers. These motor fibers originate in the primary motor cortex. This region is the bridge between the upper and lower motor neurons. The upper fibers connect the brain and spinal cord, while the lower fibers connect the spinal cord to the muscles.
- Corticobulbar tracts. The fibers here are also motor fibers from the primary motor cortex and originate in the precentral gyrus (the origin of several motor pathways). This tract innervates the cranial nerves linked to the head and face.
- Temporopont