Topics

Topic

design image
Abducens nerve (orbital part )

The Abducens nerve (orbital part), also known as the sixth cranial nerve or cranial nerve VI, is a slender motor nerve responsible for innervating the lateral rectus muscle within the orbit. This nerve passes through the superior orbital fissure to enter the orbit, where it supplies the lateral rectus muscle, facilitating the abduction of the eyeball (lateral gaze). The orbital part represents the segment of the nerve after it enters the orbit and is crucial in the clinical evaluation of extraocular muscle function, especially in the context of sixth nerve palsy or orbital pathology.

Synonyms

  • Abducens nerve (orbital segment)

  • Cranial nerve VI (orbital part)

  • Lateral rectus nerve

  • Abducent nerve (orbital part)

Function

  • Provides motor innervation to the lateral rectus muscle of the eye.

  • Facilitates abduction of the eyeball (moving the eye laterally).

  • Essential for coordinated horizontal gaze.

MRI Appearance

  • T1-Weighted Imaging:

    • The Abducens nerve appears as a small, linear, low to intermediate signal structure within the orbital apex, lateral to the optic nerve.

  • T2-Weighted Imaging:

    • The nerve is typically isointense relative to surrounding soft tissues; better visualized against the hypointense background of orbital fat.

  • STIR (Short Tau Inversion Recovery):

    • The nerve may appear isointense ; STIR is particularly useful for detecting inflammation, edema, or nerve thickening.

    • Pathology (neuritis, edema) will cause the nerve to become more prominent or hyperintense on STIR sequences.

CT Appearance

  • The Abducens nerve (orbital part) is generally not directly visualized due to its small size.

MRI images

Abducens nerve mri image