The cerebral peduncles are the two stalks that attach the

cerebrum The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb ...

to the brainstem. They are structures at the front of the

midbrain The midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. The name comes from the Greek ''mesos'', " ...

which arise from the ventral

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of Va ...

and contain the large ascending (sensory) and descending (motor) nerve tracts that run to and from the

from the pons. Mainly, the three common areas that give rise to the cerebral peduncles are 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. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consistin ...

, the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

and the cerebellum. The region includes the

tegmentum The tegmentum (from Latin for "covering") is a general area within the brainstem. The tegmentum is the ventral part of the midbrain and the tectum is the dorsal part of the midbrain. It is located between the ventricular system and distinctive ba ...

crus cerebri The cerebral crus (crus cerebri) is the anterior portion of the cerebral peduncle which contains the motor tracts, travelling from the cerebral cortex to the pons and spine. The plural of which is cerebral crura. In some older texts this is calle ...

and

pretectum In neuroanatomy, the pretectal area, or pretectum, is a midbrain structure composed of seven nuclei and comprises part of the subcortical visual system. Through reciprocal bilateral projections from the retina, it is involved primarily in mediati ...

. By this definition, the cerebral peduncles are also known as the basis pedunculi, while the large ventral bundle of efferent fibers is referred to as the

cerebral crus The cerebral crus (crus cerebri) is the anterior portion of the cerebral peduncle which contains the motor tracts, travelling from the cerebral cortex to the pons and spine. The plural of which is cerebral crura. In some older texts this is call ...

or the pes pedunculi. The cerebral peduncles are located on either side of the midbrain and are the frontmost part of the midbrain, and act as the connectors between the rest of the

and the

thalamic nuclei This traditional list does not accord strictly with human thalamic anatomy. Nuclear groups of the thalamus include: *anterior nuclear group ** anteroventral nucleus ** anterodorsal nucleus ** anteromedial nucleus **superficial ("lateral dorsal" ...

and thus the

. As a whole, the cerebral peduncles assist in refining motor movements, learning new motor skills, and converting

proprioceptive Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neurons ...

information into balance and posture maintenance. Important fiber tracts that run through the cerebral peduncles are the

corticospinal The pyramidal tracts include both the corticobulbar tract and the corticospinal tract. These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (''co ...

, corticopontine, and

corticobulbar tract In neuroanatomy, the corticobulbar (or corticonuclear) tract is a two-neuron white matter motor pathway connecting the motor cortex in the cerebral cortex to the medullary pyramids, which are part of the brainstem's medulla oblongata (also called ...

s. Damage to the cerebral peduncles results in unrefined motor skills, imbalance, and lack of

proprioception Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neurons ...

Structure

The descending upper fibers from the

internal capsule The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the ...

continue on through the midbrain and are then seen as the fibers in the cerebral peduncles. The corticopontine fibers are found in the outer and inner third of the cerebral peduncle, these are the cortical input to the pontine nuclei. The corticobulbar and corticospinal fibers are found in the middle third of the cerebral peduncle. The corticospinal tract exits the internal capsule and is seen in the mid portion of the cerebral peduncles.

Cranial nerves

Cranial nerve 3 ( oculomotor nerve) appears ventrally between the two cerebral peduncles in the

interpeduncular fossa The interpeduncular fossa is a deep depression of the ventral surface of the midbrain between the two crura cerebri. It has been found in humans and macaques, but not in rats or mice, showing that this is a relatively new evolutionary region. A ...

. Cranial nerve 4 (

trochlear nerve The trochlear nerve (), ( lit. ''pulley-like'' nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates just one muscle: the superior oblique muscle of the eye, which operates through the pu ...

) wraps around the lowest part of the cerebral peduncle.

Additional images

File:Gray677.png, Scheme showing the connections of the several parts of the brain File:Gray684.png, Deep dissection of brain-stem (lateral view) File:Gray705.png, Dissection showing the projection fibers of the cerebellum File:Gray720.png, Median sagittal section of brain File:Gray773.png, The left optic nerve and the optic tracts File:Gray792.png, Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ File:Human brainstem anterior view 2 description.JPG, Human brainstem anterior view

References

External links

Diagram

NIF Search - Cerebral Peduncle
via the

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{{Authority control Cerebrum Central nervous system pathways

Structure

Cranial nerves

Additional images

See also

References

External links