Corticopontine fibers are projections from the cerebral cortex

Cerebral cortex

The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...

 to the pontine nuclei

Pontine nuclei

The pontine nuclei are a part of the pons involved in motor activity. Corticopontine fibres carry information from the primary motor cortex to the ipsilateral pontine nucleus in the ventral pons, and the pontocerebellar projection then carries that information to the contralateral cerebellum via...

.

Depending upon the lobe of origin, they can be classified as frontopontine fibers

Frontopontine fibers

The frontopontine fibers are situated in the medial fifth of the base of the cerebral peduncles; they arise from the cells of the frontal lobe and end in the nuclei of the pons....

, parietopontine fibers, temporopontine fibers

Temporopontine fibers

In the human nervous system the temporopontine fibers, a component of the corticopontine tract, are lateral to the cerebrospinal fibers; they originate in the temporal lobe and end in the nuclei pontis....

 and occipitopontine fibers.

They are motor fibers that stretch from the precentral gyrus (motor strip) to the nuclei of cranial nerves

Cranial nerves

Cranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves...

 V (trigeminal), VII (facial) and XII (hypoglossal). These fibers run alongside the corticospinal fibers.

Clinical significance

Several clinical phenomena result from injury to the corticopontine fibers. The corticopontine fibers to cranial nerves V and XII descend to bilateral nuclei. Injury to these fibers result in tongue weakness (cranial nerve XII) and jaw weakness (cranial nerve V) but not full paralysis. The corticopontine fibers to cranial nerve VII descend to innervate bilateral sub-nuclei that supply the forehead but only contralateral to the sub-nuclei that supply the lower face. Injury to these fibers results in paralysis of the lower face, but only weakness of the forehead.