Corticopontine fibers are projections from

layer V The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of neural integration in the central nervous system, and plays a key ...

of the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...

to the

pontine nuclei The pontine nuclei (or griseum pontis) are all the neurons of the ventral pons. Corticopontine fibres project from the primary motor cortex to the ipsilateral pontine nucleus; pontocerebellar fibers then relay the information to the contralater ...

of the

ventral pons The basilar part of pons, also known as basis pontis, or basilar pons, is the ventral part of the pons (ventral pons) in the brainstem; the dorsal part (dorsal pons) is known as the pontine tegmentum. The basilar part of the pons makes up two thi ...

. They represent the first link in a cortico-cerebello-cortical pathway mediating neocerebellar control of the

motor cortex The motor cortex is the region of the cerebral cortex involved in the planning, motor control, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...

. The pathway is especially important for voluntary movements. Depending upon the lobe of origin, they can be classified as

frontopontine fibers The frontopontine fibers or frontopontine tract are corticopontine fibers projecting from the cortex of the frontal lobe to the pons. In the internal capsule, the fibers descend predominately in the anterior limb (but some also in the posterior ...

, parietopontine fibers, temporopontine fibers or occipitopontine fibers. Fibers from the

frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a Sulcus (neur ...

and the

parietal lobe The parietal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integra ...

are more numerous.

Anatomy

Origin

All corticopontine fibers arise from

pyramidal neuron Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal cells are the primary excitation units of the mammalian prefrontal cort ...

s in

of the

. They include fibers of the

premotor The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans ...

somatosensory The somatosensory system, or somatic sensory system is a subset of the sensory nervous system. The main functions of the somatosensory system are the perception of external stimuli, the perception of internal stimuli, and the regulation of bod ...

extrastriate The extrastriate cortex is the region of the occipital cortex of the mammalian brain located next to the primary visual cortex. Primary visual cortex (V1) is also named striate cortex because of its striped appearance in the microscope. The ext ...

posterior parietal The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory informa ...

, and

cingulate Cingulata, part of the superorder Xenarthra, is an order of armored New World placental mammals. The armadillos, whose species are split between the families Dasypodidae and Chlamyphoridae, are the only surviving members of the order. Two groups ...

cortices; there are also a few fibers originating from the

prefrontal Prefrontal may refer to: *Prefrontal bone, a skull bone in some tetrapods *Prefrontal cortex, a region of the brain of a mammal *Prefrontal scales The prefrontal scales on snakes and other reptiles are the scales adjacent and anterior to the fr ...

, temporal, and

striate cortex The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus an ...

. The corticopontine system contains a number of fibers from different areas of the cortex, and are far more numerous in total than the corticospinal fibers. Corticopontine fibers include: * Frontopontine fibers that arise from the

and are found in the medial third of the

crus cerebri The cerebral crus (crus cerebri. ''crus'' means ‘leg’ in Latin.) is the anterior portion of the cerebral peduncle which contains the motor tracts, traveling from the cerebral cortex to the pons and spine. The plural of which is cerebral crura ...

* Parietopontine fibers that arise from the

and found in the lateral part of the crus cerebri * Occipitopontine fibers that arise from the

occipital lobe The occipital lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin , 'behind', and , 'head'. The occipital lobe is the ...

and found in the lateral part of the crus cerebri * Temporopontine fibers arising from the

temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in pr ...

are also found in the lateral part of the cerebral crus

Course

All the fibers from the corticopontine system terminate in the

. The fibers descend through the sublenticular and retrolenticular of

internal capsule The internal capsule is a paired white matter structure, as a two-way nerve tract, tract, carrying afferent nerve fiber, ascending and efferent nerve fiber, descending axon, fibers, to and from the cerebral cortex. The internal capsule is situate ...

, then traverse the

midbrain The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, mo ...

through the basis pedunculi (i.e. ventral part of

cerebral peduncle The cerebral peduncles (In Latin, ''ped-'' means 'foot'.) are the two stalks that attach the cerebrum to the brainstem. They are structures at the front of the midbrain which arise from the ventral pons and contain the large ascending (sensor ...

) to reach the

and synapse with neurons that give rise to

pontocerebellar fibers The pontocerebellar fibers are the second-order neuron fibers of the corticopontocerebellar tracts that cross to the other side of the pons and run within the middle cerebellar peduncles, from the pons to the contralateral cerebellum. They arise f ...

. As the corticopontine fibres descend in the cerebral peduncle, those from the prefrontal regions are situated most medially; those from premotor and motor cortices are situated in the middle third of the peduncle, and fibers from the parietal, temporal and occipital regions that travel to the pons are in the lateral third of the cerebral peduncle. Two fiber bundles, an anterior and a posterior bundle relate the cortex to the

cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or eve ...

. The anterior bundle, is of frontopontine fibers, particularly from Brodmann areas 4 and 6 and is known as ''Arnold's bundle''. The posterior bundle is of the corticopontine fibers comprising the parietopontine, temporopontine, and occipitopontine fibers, and is known as ''Türck's bundle''.

References

External links

* https://www.csuchico.edu/~pmccaffrey/syllabi/CMSD%20320/362unit7.html * Cerebral white matter {{neuroanatomy-stub