Adjective
(anatomy, medicine) Next to a cortex; thus:
(anatomy, medicine) Abutting the cortical layer of bone, as with juxtacortical chondroma.
(anatomy, medicine) Abutting the cerebral cortex (and thus involving subcortical U-fibers), as with juxtacortical white matter lesions in multiple sclerosis.
Source: en.wiktionary.org