Not to be confused with Desiccation, Chiasm (anatomy), or Commissure.
Section of the medulla oblongata at the level of the decussation of the pyramids
Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (decussis), from Latin decem 'ten', and as 'as'). In Latin anatomical terms, the form decussatio is used, e.g. decussatio pyramidum.
Similarly, the anatomical term chiasma is named after the Greek uppercase 'Χ' (chi). Whereas a decussation refers to a crossing within the central nervous system, various kinds of crossings in the peripheral nervous system are called chiasma.
Examples include:
In the brain, where nerve fibers obliquely cross from one lateral side of the brain to the other, that is to say they cross at a level other than their origin. See for examples decussation of pyramids and sensory decussation. In neuroanatomy, the term chiasma is reserved for crossing of- or within nerves such as in the optic chiasm.
In botanical leaf taxology, the word decussate describes an opposite pattern of leaves which has successive pairs at right angles to each other (i.e. rotated 90 degrees along the stem when viewed from above). In effect, successive pairs of leaves cross each other. Basil is a classic example of a decussate leaf pattern. Decussate phyllotaxis of Crassula rupestris
In tooth enamel, where bundles of rods cross each other as they travel from the enamel-dentine junction to the outer enamel surface, or near to it.
In this "true bug", Dysdercus decussatus, in the family Pyrrhocoridae, the specific epithet refers to the bandolier-like markings on the back.
In taxonomic description where decussate markings or structures occur, names such as decussatus or decussata or otherwise in part containing "decuss..." are common, especially in the specific epithet.[1]
^Jaeger, Edmund C. (1959). A source-book of biological names and terms. Springfield, Ill: Thomas. ISBN 0-398-06179-3.
Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (decussis), from Latin...
In neuroanatomy, the sensory decussation or decussation of the lemnisci is a decussation (i.e. crossover) of axons from the gracile nucleus and cuneate...
dorsal aspect of the ventricle and thus assist in forming its roof. The decussation of superior cerebellar peduncle is the crossing of fibers of the superior...
a commissure, decussation, or neural pathway. A commissure connects the two cerebral hemispheres at the same levels, while a decussation connects at different...
The ventral supraoptic decussation is the crossover (decussation) point for signals from the left and right eye, en route respectively to the right and...
cross over to the opposite side from which they originated, known as decussation. The axons that cross over move to the outer part of the medulla oblongata...
(rostral) or below (caudal) the pyramidal decussation. Damage to the body above the pyramidal decussation will cause contralateral motor deficits. For...
(anatomy)). A midline crossing of nerves inside the brain is called a decussation (see Definition of types of crossings). In all vertebrates, the optic...
(hence the spinothalamic tract being part of the anterolateral system). Decussation usually occurs 1-2 spinal nerve segments above the point of entry. The...
can be seen a decussation of fibers which marks the transition from the medulla to the spinal cord. The medulla is above the decussation and the spinal...
enlargements within the spinal cord. There is no decussation in the lateral corticospinal tract after the decussation at the medullary pyramids. The anterior corticospinal...
'Χ,' chi). A decussation denotes a crossing of bundles of axonal fibers inside the central nervous system. As a result of such decussations: The efferent...
postero-medially towards the optic chiasm, where there is a partial decussation (crossing) of fibers from the temporal visual fields (the nasal hemi-retina)...
system. At the caudal part of the medulla these tracts cross over in the decussation of the pyramids obscuring the fissure at this point. Some other fibers...
gray matter at the base of the posterior grey column.[citation needed] Decussation of pyramids. The motor tract. Berthold, Daniel Goude, C.-H. "Pyramidbanans...
spinal nerves. Upon decussation (crossing over) from one side of the medulla to the other, also known as the sensory decussation, they are then called...
crosses the midline at its level of origin or entry (as opposed to a decussation of fibers that cross obliquely). The nine are the anterior commissure...
gather in the internal capsule before crossing over to the opposite side (decussation) in the medullary pyramids and proceeding down the spinal cord to meet...
region of each side whereas a decussation connects different brain regions. The brainstem from the front, showing a decussation of the superior pedicle and...
base of the cerebral peduncle with the cerebrospinal fibers, undergo decussation and end in the motor nuclei of the cranial nerves of the opposite side...
mesencephalon (midbrain). This was to become known as "Meynert's decussation" or as "fountain decussation". Die Bloßlegung des Bündelverlaufs im Großhirnstamme,...
fibers of the buccinator pass across the lips from side to side without decussation. Superficial to this stratum is a second, formed on either side by the...
tectum. The superior colliculi process some visual information, aid the decussation of several fibres of the optic nerve (some fibres remain ipsilateral)...
segments with the higher centers. The optic chiasm is the primary cause of decussation; nasal fibers of the optic nerve cross (so each cerebral hemisphere receives...
crossing over to the contralateral side in the medulla oblongata (pyramidal decussation), the axons travel down the spinal cord as the lateral corticospinal...
'Χ,' chi). A decussation denotes a crossing of bundles of axonal fibres inside the central nervous system. As a result of such decussations: The efferent...
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