Definition of raphe in US English:



  • 1Anatomy Biology
    A groove, ridge, or seam in an organ or tissue, typically marking the line where two halves fused in the embryo.

    • ‘They are located close to the median raphe, ventromedial to the hypoglossal nucleus.’
    • ‘Its fibers pass dorsally from an extensive anterior attachment to insert on the pharyngeal raphe, the pharyngeal tubercle of the occipital bone.’
    • ‘If the variant is bilateral the deviant muscle plate has a raphe in the median line.’
    1. 1.1 The connecting ridge between the two halves of the medulla oblongata or the tegmentum of the midbrain.
      • ‘Stimulation of 5 - HT1A receptors in the raphe regulates serotonin synthesis and release.’
      • ‘In rats, the CO2-sensitive neurons of the caudal medullar raphe act during sleep only.’
      • ‘Because most medullary raphe neurons that project to motoneurons are inhibited by vagal afferents.’
      • ‘The second pathway arises from the median raphe and enervates the hippocampus and appears to mediate resilience and adaptation to stress.’
      • ‘Second, there is a midbrain trigger, perhaps in serotonergic neurons of the dorsal raphe.’
  • 2Botany
    A longitudinal ridge on the side of certain ovules or seeds.

    • ‘The raphe is a slightly depressed area on the opposite side of the hilum from the micropyle.’
    1. 2.1 A longitudinal groove in the valve of many diatoms.
      • ‘Through the raphe, the living diatom secretes mucilage, with which it may attach to a substrate or move by gliding over the substrate.’


Mid 18th century: modern Latin, from Greek rhaphē ‘seam’.