- SYN: decussatio. [L. decussatio]- fountain d. tegmental decussations (1).- Held d. the crossing of some of the fibers arising from the cochlear nuclei to form the lateral lemniscus.- d. of medial lemniscus the intercrossing of the fibers of the left and right medial lemniscus ascending from the gracile and cuneate nuclei, immediately rostral to the level of the d. of the pyramidal tracts in the medulla oblongata. SYN: decussatio lemnisci mediales [TA], decussatio sensoria, d. of the fillet, sensory d. of medulla oblongata.- optic d. SYN: optic chiasm.- d. of pyramids [TA] the intercrossing of the bundles of corticospinal fibers at the lower border region of the medulla oblongata. SYN: decussatio pyramidum [TA], decussatio motoria, motor d..- d. of superior cerebellar peduncles [TA] the d. of the left and right superior cerebellar peduncles in the tegmentum of the caudal mesencephalon. SYN: decussatio pedunculorum cerebellarium superiorum [TA], decussatio brachii conjunctivi, d. of brachia conjunctiva, Wernekinck d..- tegmental decussations 1. the posterior tegmental d. [TA] (dorsal tegmental d. [TA], fountain d., Meynert's d.) is formed by the crossing of the left and right tectospinal and tectobulbar tracts; 2. the anterior tegmental d. [TA] (ventral tegmental d. [TA], Forel's d.) is formed by the crossing of the left and right rubrospinal and rubrobulbar tracts; both decussations are located in the mesencephalon. SYN: decussationes tegmentales [TA].- d. of trochlear nerve fibers [TA] the crossing of the two trochlear nerves at their exit through the velum medullare anterius. SYN: decussatio fibrarum nervorum trochlearium [TA].
* * *de·cus·sa·tion .dē-(.)kə-'sā-shən n1) the action of intersecting or crossing (as of nerve fibers) esp. in the form of an X see DECUSSATION OF PYRAMIDS2 a) a band of nerve fibers that connects unlike centers on opposite sides of the nervous systemb) a crossed tract of nerve fibers passing between centers on opposite sides of the central nervous system: COMMISSURE
* * *n.a point at which two or more structures of the body cross to the opposite side. The term is used particularly for the point at which nerve fibres cross over in the central nervous system.
* * *de·cus·sa·tion (de″kə-saґshən) a crossing over; see decussatio.
Medical dictionary. 2011.