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Cerebral crus

he cerebral crus (also known as the crus cerebri) is a prominent bundle of nerve fibers located in the anterior portion of the midbrain. It forms the large ventral part of the cerebral peduncle and contains descending motor tracts connecting the cerebral cortex to the brainstem and spinal cord. The cerebral crus plays a critical role in voluntary motor control and is a key structure evaluated in both clinical neuroanatomy and neuroimaging.

Synonyms:

  • Crus cerebri

  • Basis pedunculi

  • Cerebral peduncle (Note: "cerebral peduncle" is a broader term, but often used interchangeably)

  • Pes pedunculi

Arterial Supply:

  • Supplied primarily by branches of the posterior cerebral artery (PCA), particularly the paramedian and lateral branches.

  • Additional contributions from the posterior communicating artery and the anterior choroidal artery.

Venous Drainage:

  • Drained by the basal vein of Rosenthal.

  • Additional drainage via the peduncular veins into the great cerebral vein (vein of Galen).

Function:

  • Contains major descending motor pathways (corticospinal, corticobulbar, and corticopontine tracts).

  • Facilitates voluntary motor control of the body and face.

  • Conveys information from the cerebral cortex to the brainstem and spinal cord.

MRI Appearance:

  • T1-weighted images:

    • The cerebral crus appears as a hypointense (dark) band relative to the surrounding white matter.

    • Clear anatomical delineation, but pathology (e.g., infarct) may cause focal signal change.

  • T2-weighted images:

    • Appears hyperintense (bright) compared to T1, but generally isointense to other white matter tracts.

    • Lesions or demyelination manifest as areas of increased signal intensity.

  • FLAIR (Fluid Attenuated Inversion Recovery):

    • Normally isointense to adjacent white matter.

    • Pathological conditions (infarction, demyelination) can cause focal hyperintensity.

CT Appearance:

  • On non-contrast CT, the cerebral crus is not distinctly visualized from surrounding midbrain structures due to similar density.

MRI images

Cerebral crus mri et axial image