[UW Anatomy |
Contents]
Function:
Pontine grey nuclei are involved in conveying information from the
motor cortex to the cerebellum regarding intended movement(s) of
CONTRA. arm and leg. There are lots of pontine grey neurons,
indicating the importance of the cortico-ponto-cerebellar circuit in
overall motor function.
Pathway:
Pontine grey neurons lie in the basilar (ventral) pons among the
numerous bundles of corticospinal, corticobulbar and corticopontine
fibers (there are a great many more of these than corticospinal and
corticobulbar fibers). Corticopontine fibers arise in IPSI. motor
associated cortical areas and provide the pontine grey neurons with
information regarding intended movement(s) of the CONTRA. side of the
body (remember that corticospinal fibers cross). Pontine grey neurons
possess pontocerebellar axons that CROSS through the other side of
the basilar pons, enter the MIDDLE CEREBELLAR PEDUNCLE (or brachium
pontis) and terminate in the cerebellar cortex (neurons in the LEFT
pontine grey project to the RIGHT side of the cerebellum via the
RIGHT middle cerebellar peduncle).
Deficits:
Lesion in the pontine grey results in incoordination of the CONTRA.
arm and leg. In contrast, a lesion of the middle cerebellar peduncle
results in motor incoordination of the IPSI. arm and leg.
Other Note:
Extra tidbit! Since there is only one source of CLIMBING FIBERS
(inferior olive), pontocerebellar (as well as cuneocerebellar and
dorsal spinocerebellar) fibers terminate in the cerebellum as MOSSY
FIBERS.