me·di·al / ˈmēdēəl/ • adj. technical situated in the middle, in particular: ∎  Anat. & Zool. situated near the median plane of the body or the midline of an organ.The opposite of lateral. ∎  Phonet. (of a speech sound) in the middle of a word. ∎  Phonet. (esp. of a vowel) pronounced in the middle of the mouth; central.DERIVATIVES: me·di·al·ly adv.

medial † (math.) mean XVI; that is in the middle; ordinary. XVIII. — late L. mediālis, f. medius MID; see -AL1.
So median (first in anat.) m. vein XVI; (gen.) middle XVII. — F. médian or L. mediānus; cf. MEAN3.

medial (mee-di-ăl) adj.
1. relating to or denoting parts of the body that are closest to the median plane of the body.

2. relating to or situated in the central region of an organ, tissue, or the body.