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Cerebral Peduncles

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Mainly, the three common areas that give rise to the cerebral peduncles are the cortex, the spinal cord and the cerebellum[1]. The cerebral peduncle, by most classifications, is everything in the mesencephalon except the tectum.[citation needed] The region includes the midbrain tegmentum, crus cerebri and pretectum. 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 crus cerebri or the pes pedunculi.

The cerebral peduncle are located on either side of the mid brain and are the most anterior part of the midbrain, they act as the connectors between the rest of the midbrain and the thalamic nuclei and thus the cerebrum. As a whole the cerebral peduncles assists in refining motor movements, learning of new motor skills, and converting proprioceptive information into balance and posture maintenance[2][3]. The cerebral peduncles consists of three cerebellar peduncles on each side of the mid brain, which act as connections between the cerebellum and the brainstem. The axon fiber bundles that act as the connections can either preform input or output tasks depending on the type of signal they receive. These are the three input and output tracts of the cerebellum: superior (brachium conjunctivum), middle (brachium pontis), and inferior (restiform body) cerebellar peduncles. Important fiber tracts that run through the cerebral peduncles are: cortico-spinal, cortico-pontine, and cortico-bulbar tracts.

Damage to the cerebral peduncles results in unrefined motor skills, imbalance, and lack of proprioception[4].

Structure

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The descending fibers from the internal capsule continue on through the midbrain and are then seen as the fibers in the cerebral peduncles[5]. The superior, middle, and inferior cerebral peduncles connect the brain stem to the cerebellum. The superior peduncle connects the cerebellum to the midbrain, while the middle peduncle connects the pons to the cerebellum. The middle peduncle is the largest of the peduncles[6]. The inferior peduncle connects the medulla to the cerebellum. In terms of input and output signals, the middle and inferior peduncles are the primary peduncles for input information. While output from the cerebellum is via the superior peduncle[7]. The superior peduncle also connects the interposed nuclei to the red nucleus, as well as the dentate nucleus to the ventral lateral nucleus of the thalamus which relays to the cerebral motor cortex[8].

Superior peduncle (brachium conjunctivum) Middle peduncle (brachium pontis) Inferior peduncle (restiform body)
Coordination of the arms and legs, as well as transportation of information from the cerebellum to the midbrain and pons. Acts primarily as output from the cerebellum. Originates at the pontine nuclei. There are three types of nervous tissue: superior, inferior, and deep. Connects the pons to the cerebellum, assists in the intention for motor control. Largest of the peduncles, acts primarily as an input to the cerebellum. Responsible for proprioceptive information. Accomplishes this by connecting the cerebellum to the medulla. Acts primarily as an input to the cerebellum.

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Fiber tracts

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The contralateral red nucleus is the origin for the rubrospinal tract whose main function is to influence limb flexor muscles. The superior cerebellar peduncle facilitates the connection between the interposed nuclei and the red nucleus. The pontine nuclei exclusively connect to the cerebellum via the middle peduncle forming the cortico- pontine tract[10]. . The cortico-pontine fibers are found in the outer and inner third of the cerebral peduncle, these are the cortical input to the pontine nuclei[11]. The cortico-bulbar and cortico-spinal fibers are found in the middle third of the cerebral peduncle[12]. The cortico-spinal tract exits the internal capsule and is seen in the mid portion of the cerebral peduncles.

Cranial nerves

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Cranial nerve 5 (trigeminal nerve) is attached along the middle cerebral peduncle. Cranial nerve 3 (oculomotor nerve) appears ventrally between the two cerebral peduncles in the interpeduncular fossa. Cranial nerve 4 (trochlear nerve) wraps around the lowest part of the cerebral peduncle[13].

References

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  1. ^ Saladin, Kenneth (2010). Anatomy & Physiology The Unity of Form and Function. New York, NY: McGraw-Hill Companies, Inc.
  2. ^ Swenson, Rand. Review of Clinical and Functional Neuroscience (online ed.). Chapter 8B - Cerebellar Systems: Swenson 2006. {{cite book}}: |access-date= requires |url= (help)CS1 maint: location (link)
  3. ^ HENDELMAN, WALTER J. Atlas of Functional Neuroanatomy (PDF). CRC Press LLC. Retrieved 26 November 2015.
  4. ^ "Cerebral Peduncle Anatomy". Healthline. Retrieved 26 November 2015.
  5. ^ HENDELMAN, WALTER J. Atlas of Functional Neuroanatomy (PDF). CRC Press LLC. Retrieved 26 November 2015.
  6. ^ Swenson, Rand S. Review of Clinical and Functional Neuroscience. Chapter 8B: Swenson 2006. Retrieved 26 November 2015.{{cite book}}: CS1 maint: location (link)
  7. ^ Swenson, Rand S. Review of Clinical and Functional Neuroscience. Chapter 8B: Swenson 2006. Retrieved 26 November 2015.{{cite book}}: CS1 maint: location (link)
  8. ^ Swenson, Rand S. Review of Clinical and Functional Neuroscience. Chapter 8B: Swenson 2006. Retrieved 26 November 2015.{{cite book}}: CS1 maint: location (link)
  9. ^ Josiah, Andy. "What are Cerebellar Peduncles?". wiseGEEK. 2003-2015 Conjecture Corporation. Retrieved 26 November 2015.
  10. ^ Swenson, Rand S. Review of Clinical and Functional Neuroscience. Chapter 8B: Swenson 2006. Retrieved 26 November 2015.{{cite book}}: CS1 maint: location (link)
  11. ^ HENDELMAN, WALTER J. Atlas of Functional Neuroanatomy (PDF). CRC Press LLC. Retrieved 26 November 2015.
  12. ^ HENDELMAN, WALTER J. Atlas of Functional Neuroanatomy (PDF). CRC Press LLC. Retrieved 26 November 2015.
  13. ^ HENDELMAN, WALTER J. Atlas of Functional Neuroanatomy (PDF). CRC Press LLC. Retrieved 26 November 2015.
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