The human brain (and the brains of most higher organisms) is a wonderful, complex organ. The various regions work together to allow the organism to process information, make decisions, and instruct the various body parts to react accordingly. However, none of this functionality is possible without the various “pathways” distributing information between the various regions. A prominent and essential pathway is the paired cerebral peduncles.

The cerebral peduncles are essential parts of the midbrain. Several distinct fiber bundles collect together in a cylindrical shape. These fibers act like a highway between various brain and spinal cord regions, conveying sensory and motor information and refining movement-related impulses.

While the brain’s highways are essential for transporting sensory information and motor responses to and from the brain, many highways also synthesize information and “act” accordingly. Below we’ll investigate the cerebral peduncles in more detail, examining what they are, why they are essential, how the peduncles function, and what complications they experience.

Cerebral Peduncles OverviewComplications Of The Cerebral PedunclesTreatment Of The Cerebral PeduncleConclusion

Cerebral Peduncles Overview

Complications Of The Cerebral Peduncles

Treatment Of The Cerebral Peduncle

Conclusion

A peduncle is thestalk or stemof an inflorescence (flower) andconnectsthe “flower head” to the rest of the plant, which makes it an apt name for cerebral peduncles.

Without the cerebral peduncle, an organismwould not function correctly. The “cerebral peduncle” refers to thecrus cerebri, substantia nigra, and tegmentum,which combine to formpaired cylindrical-shapedfiber collections.

Most cerebral peduncle fibersoriginate in the cerebral cortexandconnect to nuclei in the cerebellum(via the pons) or the spinal cord. The fibers aregrouped according to their functionand which part of the brain they attach to.

Thesegroupings (arrangements) include:

As with all parts of the human body, the cerebral peduncles arecritical for the organism’s effective functioning.

The Cerebral Peduncles Location And Structure

The cerebral peduncles arelocated 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 thetopmost spinal cordregion and connects theforebrain(via the thalami) to the cerebellum and pons.

The cerebral peduncles “branch off,“connecting to either side of the brainand leaving agapbetween the two stalks. We refer to this separation as theinterpeduncular cistern(a chamber filled with cerebrospinal fluid).

The cerebral peduncles are mostly white matter tracts. However, thecompositionof the cerebral peduncleschanges along their length(divided into two parts adjacent to the inferior colliculus and the superior colliculus).

Within theinferior colliculusregion, we find:

In addition to the above, within thesuperior colliculus regionof the cerebral peduncle, we find:

What Is The Cerebral Peduncles Purpose?

The cerebral peduncles play a critical role inpassing information(nerve impulses) between the various parts ofthe brain(theforebrain and the cerebellum)and the spinal cordto other parts of thecentral nervous system.

However, the function of the cerebral peduncles is not limited to “passing on” information. Theyalsoplay a role in“refining” the instructionspassed 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, thepeduncles “adjust” the instructionsto fit the situation.

If the instructions were not tailored to fit the need, our responses would be exaggerated, insufficient, and ungainly.

The cerebral peduncles also assist inlearning new motor skillsand maintainingbalance and posturethrough interpretingproprioceptive stimuli.

The cerebral peduncles are aproduct of their various components. Each component is responsible fordifferent functionsand information processing; some of theseinclude:

The crus cerebricontains four fiber tracts:

Thecrus cerebriconnects thecerebral hemispheres to thecerebellumthrough a network of neurons. These neurons are mostly thewhite matter(axons covered in myelin sheaths) of motor neurons.

The crus cerebri iscritical for transporting nerve impulsesfrom the brain, down the spinal cord, and eventually to the relevant muscles.

Together theanterior pars reticulataand theposterior pars compactafrom the substantia nigra, a collection ofpigmented nuclei. The substantia nigra separates the crus cerebri from the tegmentum.

These cells mediate movementandmotor coordination(usually inhibiting neurons, particularly those in the caudate nucleus and putamen).

These cells also have aninhibitory actionthrough the gamma-aminobutyric acid present in their cells.

This inhibitory effectprevents/blocks impulsesfrom your brain from reaching the muscles.

The pars compacta and reticulata (together with the globus pallidus)create the striatum.

The substantia nigra plays afundamental rolein assisting withmovement, facilitatingconnectionsin the brain (as part of thebasal ganglia), and controlling variouschemical components(e.g., dopamine).

The tegmentum consists offiber tracts and two differentiated color areas:

Nerve fibers(crossed fibers) from thecerebellar pedunclesurround and (some) terminate in the red nucleus. These fibers receive information from themotor cortex.

This region deals withpain suppressionthroughendorphinproduction.

Although some sources view the substantia nigra as part of the tegmentum, others view it as a separate structure in the midbrain.

The tegmentum isessential for alertness, movement, and processing of pain.

Somecomplications include:

Trauma is a significant causeof complications of cerebral peduncles. When the cerebral peduncles are injured, thesymptoms present in thecorresponding 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 reasonfor complications in the cerebral peduncles.

Some of thesediseases include:

An infraction is whenblood vesselsleading to a particular organ (or part thereof)become blocked(often through swelling). This blockage leads to the “starvation” ofcellsin the affected area, whichbegin to die.

Duringa study in 2019, researchers discovered that the leading causes for these blockages in blood flow to the cerebral peduncles were due to pressure on the vertebrobasilar arteryand its branches throughstenosis or occlusion( a full or partial blockage of a blood vessel).

Stenosisisnarrowing spaces in the spine, applying pressure to the spinal cord and causingpain and discomfort, which could eventually lead to paralysis/loss of function.

Anocclusionin the intracranial regions of the brain couldcause ischemia(lack of oxygen). This ischemia leads toWallenberg Syndrome,Locked-In Syndrome, andTop-of-the-basilar syndrome, depending on where the blockage occurs.

These diseases range in consequences/symptoms, fromataxia and disturbances in brainfunction toquadriplegia.

Certain neurons fail to migrate duringfetal development(especially during weeks 12 and 24). This failure results in theabsence of grooves and foldsdeveloping on the brain’s surface.

The term“lesion” is a collective descriptionof anydamaged tissuein the brain. Althoughall tumors are lesions, not all lesions are tumors.

Unfortunately,tumorsmay develop in themidbrainand the cerebral peduncle. An example isgliomas. This type of tumor develops whenglial cellsgrow out of control. While some patientsmay not show symptoms, these tumors are frequentlycancerous(malignant).

These tumors areoften fatalas they arechallenging to treat/reach for surgery andmay spreadto other areas in the brain.

There arethree types of gliomas:

Somesymptoms of gliomainclude:

Thetype of disease/complication affecting the cerebral peduncles and surrounding brain regionsdictatesthe necessarytreatment.

In several cases, thetreatment includes:

For example,benign astrocytomas(a type of tumor) are usually treated withradiation therapy, assurgery is dangerousin this sensitive brain region. However, astudy published in 2002looked at 7 child patients who had theirtumors surgically removed.

Whilemost patients were finein the long term,somepatientsexperienced a loss of motor,oculomotor,ormemory functionin the short term. After the surgery, only1 patientexperienced aresurgenceof benign astrocytomas.

Occasionally there isno treatment, andmanagementof the disease/symptoms remains. Althoughgeneticsplay a significant factor,prevention is better than trying to fix the issue.

The cerebral peduncles form part of the midbrain, an essential part of the mammalian brain. The cerebral peduncles facilitate sensory and motor impulses from the brain to the muscles and vice versa. The cerebral peduncle is a collection of white and gray matter that play a fundamental role in the brain’s movement, pain responses, and chemical composition. They are paramount in refining motor signals from the cerebral cortex.

Related posts:Substantia Nigra FunctionVentral Root (Location + Function)Corticospinal TractMotor Cortex FunctionAnterior Horn (Location and Function)

Reference this article:Practical Psychology. (2022, September).Cerebral Peduncles.Retrieved from https://practicalpie.com/cerebral-peduncles/.Practical Psychology. (2022, September). Cerebral Peduncles. Retrieved from https://practicalpie.com/cerebral-peduncles/.Copy

Reference this article:

Practical Psychology. (2022, September).Cerebral Peduncles.Retrieved from https://practicalpie.com/cerebral-peduncles/.Practical Psychology. (2022, September). Cerebral Peduncles. Retrieved from https://practicalpie.com/cerebral-peduncles/.Copy

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