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Lateral recess fourth ventricle

The lateral recesses of the fourth ventricle are slender, tapering extensions that project laterally from the main cavity of the fourth ventricle, located in the posterior fossa of the brain. They extend outward and slightly upward, terminating at the foramina of Luschka, which allow cerebrospinal fluid (CSF) to exit the ventricular system into the subarachnoid space of the cerebellopontine angle cistern. Recognition of the lateral recesses is important in neuroimaging for assessing pathologies such as cysts, tumors, and hydrocephalus, and for understanding the spread of CSF or pathological processes.

Anatomical Location and Features:

  • Situated at the lateral aspects of the fourth ventricle.

  • Extend from the ventricular cavity toward the cerebellopontine angle.

  • End at the foramina of Luschka, lateral to the brainstem.

  • Bordered medially by the inferior cerebellar peduncle and laterally by the flocculus of the cerebellum.

Synonyms

  • Lateral aperture of the fourth ventricle

  • Foramen of Luschka

  • Luschka’s foramen

  • Lateral ventricular recess

MRI Appearance

T2-Weighted Images:

  • The lateral recess appears as a CSF-filled linear or triangular extension from the fourth ventricle.

  • High signal intensity (bright), isointense to CSF.

  • Well-delineated borders against adjacent brainstem and cerebellar tissue.

  • Helps visualize patency and detect any encroaching lesions or cystic changes.

T1-Weighted Images:

  • The lateral recess is seen as a low signal (dark) structure, similar to CSF.

  • Appears as a thin extension lateral to the main fourth ventricular cavity.

  • Visualization may be less conspicuous compared to T2, but still useful for anatomical assessment.

FLAIR Sequence:

  • The lateral recess, filled with normal CSF, shows low signal (dark), as CSF is suppressed on FLAIR.

  • Becomes more conspicuous in the presence of abnormal signal (e.g., blood, pus, proteinaceous material) or pathology obstructing CSF flow.

CT Appearance

Non-Contrast CT:

  • The lateral recess of the fourth ventricle is difficult to delineate specifically due to limited soft tissue contrast.

  • Appears as a low-density (dark) region lateral to the fourth ventricle, isodense with CSF.

  • May become more apparent if dilated (e.g., in obstructive hydrocephalus) or distorted by mass lesions.

  • Better appreciated in thin-section or multiplanar reconstructions.

MRI images

Lateral recess of fourth ventricle mri 3t axial image

MRI images

Lateral recess of fourth ventricle mri 3t sagittal image