What does contralateral mean?
Contralateral is an adjective meaning located on, relating to, or affecting the opposite side of the body from a specified point of reference. It belongs primarily to the vocabulary of anatomy, neurology, and medicine, where precision about sides of the body matters greatly. Because many nerve pathways cross from one half of the brain to the other as they descend through the brainstem, damage to one cerebral hemisphere usually produces symptoms on the contralateral side: a stroke in the left hemisphere may leave the right arm weak, an effect described as contralateral weakness or hemiparesis. Clinicians use the term most often in explicit contrast with its counterpart 'ipsilateral', which denotes the same side rather than the opposite one. Outside medical contexts the word appears mainly in scientific writing about movement, sensation, and brain function. Though formal and technical, it is a useful term for anyone reading about neuroscience or rehabilitation, since so much of how the nervous system is wired depends on this left–right crossover.
adjectiveRelating to or situated on the opposite side of the body from a given point of reference; used chiefly in anatomy and medicine to describe structures, movements, or effects occurring on the side opposite to the one affected or mentioned.
- Situated on or affecting the opposite side of the body from a specified point, structure, or lesion.
- (Of movement or reflexes) involving or produced by muscles or limbs on the opposite side of the body.
"A stroke affecting the left hemisphere of the brain typically causes weakness on the contralateral side of the body."
"The patient exhibited reduced grip strength in the contralateral hand after the right-hemisphere stroke."
"Damage to the cerebellum often produces ipsilateral signs, whereas cerebral lesions tend to cause contralateral deficits."
Because the brain's motor nerves cross over in the brainstem, your left hemisphere controls your right hand — which is why doctors constantly talk about 'contralateral' effects when describing strokes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does contralateral come from?
Contralateral derives from two Latin roots joined in modern scientific Latin: 'contra-', meaning against or opposite, and 'lateralis', from 'latus' meaning side. The compound was formed within anatomical Latin, the international language of European medicine, and entered English usage as physicians adopted Latinate technical vocabulary; precise dating of its first appearance in English is uncertain, though such terms were well established by the nineteenth century. It shares the 'contra-' element with words like 'contrary' and 'contrast' and the '-lateral' element with 'lateral', 'bilateral', 'multilateral', and 'unilateral'.
Related word forms
How contralateral is actually used
Primarily a technical term of anatomy, neurology, and medicine; rare outside clinical, scientific, or academic writing. It is almost always used in contrast with its antonym 'ipsilateral' (same side), and occasionally with 'bilateral' (both sides). The word carries no emotional connotation — it is neutral and descriptive. It functions attributively ('contralateral limb') far more often than predicatively.
Easily confused with contralateral
Ipsilateral means on the same side of the body as the reference point, whereas contralateral means on the opposite side.