Cerebral peduncle Information & Cerebral peduncle Links at HealthHaven.com

Brain: Cerebral peduncle
	Superficial dissection of brain-stem. Ventral view. ("Cerebral peduncle" visible in red at center-right.)
	Section through superior colliculus showing path of oculomotor nerve. (Crus cerebri labeled at lower left.)
Latin	pedunculus cerebri
Gray's	subject #188 800
NeuroNames	hier-478
MeSH	Cerebral+Peduncle
NeuroLex ID	birnlex_1202

<Saladin, Kenneth. Anatomy & Physiology The Unity of Form and Function. New York, NY: McGraw-Hill Companies, Inc., 2010.>

The cerebral peduncle, by most classifications, is everything in the mesencephalon except the tectum. The region includes the midbrain tegmentum, crus cerebri, substantia nigra 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 There are numerous nerve tracts located within this section of the brainstem. Of note, in the cerebral peduncular loop fibers from motor areas of the brain project to the cerebral peduncle and then project to various thalamic nuclei.

In as much as the peduncles are an anatomic landmark, for details regarding the function of this area interested readers are referred to the individual referenced articles. On a broad scale, though, this area contains many nerve tracts conveying motor information to and from the brain to the rest of the body.

Important fibers running through the cerebral peduncles include the corticospinal tract and the corticobulbar tract, among others.

Mainly, the three common areas that give rise to the cerebral peduncles are the cortex, the spinal cord and the cerebellum. Uncontrolled motor commands that only have Excitatory Postsynaptic Potentials (EPSPs) would produce uncoordinated, jerky and even spastic movements. To combat this, the brain uses the middle, superior and inferior peduncles in order to produce precise, fine controlled movement. When the cortex wants to send a command to the body, especially when concerning voluntary muscle movement, the command is first sent through the middle peduncle. At the same time, the spinal cord will send proprioceptive messages through the inferior peduncle. The sensory information concerning proprioception from the spinal cord will come from two afferent tracts, which are the "posterior (dorsal) and anterior (ventral) spinocerebellar" (Saladin 489). The spinocerebellar tracts will "travel through the lateral column and carry proprioceptive signals from the limbs and trunk" (Saladin 489). The information from the middle and inferior peduncles will then travel to the cerebellum. In the cerebellum, the correct amount of Inhibitory Postsynaptic Potential (IPSPs) will be added to the cortex's original command. The completed command will then leave the cerebellum through the superior peduncle and travel back to the cortex. Afterwards, the cortex will be able to send a finely controlled motor command for precise movement.

[edit] Additional images

Scheme showing the connections of the several parts of the brain.	Superficial dissection of brain-stem. Lateral view.	Dissection of brain-stem. Lateral view.	Deep dissection of brain-stem. Lateral view.
Dissection showing the projection fibers of the cerebellum.	Median sagittal section of brain.	The left optic nerve and the optic tracts.	Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.
Human brainstem anterior view