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Ventrolateral sulcus of medulla oblongata

The ventrolateral sulcus of the medulla oblongata is a longitudinal groove found on the anterolateral aspect of the medulla oblongata, an essential structure at the lower part of the brainstem. This sulcus plays a key anatomical and clinical role as it marks the exit point for several important cranial nerves, most notably the hypoglossal nerve (CN XII). Its identification is crucial in neuroanatomy and radiology, especially in MRI and CT imaging, for understanding brainstem pathology and guiding neurosurgical approaches.

SYNONYMS

  • Anterolateral sulcus of medulla oblongata

  • Ventrolateral groove of medulla

  • Sulcus anterolateralis medullae oblongatae

ANATOMICAL LOCATION

  • Situated on the ventral (anterior) aspect of the medulla oblongata

  • Lies between the pyramid (medially) and the olive (laterally)

  • Extends longitudinally along the medulla

FUNCTION

  • Serves as the point of exit for the rootlets of the hypoglossal nerve (CN XII)

  • Anatomical landmark for neuroanatomical orientation of the medulla

  • Aids in distinguishing the pyramids from the olivary bodies on imaging and during dissection

  • Indirectly involved in tongue movements via the hypoglossal nerve

ARTERIAL SUPPLY

  • Primarily supplied by branches of the anterior spinal artery

  • Additional contributions from the vertebral artery and branches of the posterior inferior cerebellar artery (PICA)

VENOUS DRAINAGE

  • Drained by small medullary veins

  • Venous blood ultimately drains into the anterior and posterior spinal veins and the inferior petrosal sinus via medullary and spinal venous plexuses

MRI Appearance

  • T1-weighted images: The sulcus appears as a thin hypointense (dark) line separating the higher signal intensity of the pyramids and the olive

  • T2-weighted images: The sulcus is seen as a thin hyperintense (bright) line due to the interface between CSF and medullary tissue

CT Appearance

  • The ventrolateral sulcus is not directly visualized on routine CT scans due to limited soft tissue contrast

MRI images

Ventrolateral sulcus MRI 3T axial image