Definition of ramus in English:



  • 1Anatomy
    An arm or branch of a bone, in particular those of the ischium and pubes or of the jawbone.

    • ‘The section passes through the mandibular ramus.’
    • ‘At the inferior border of the pubis the two corpora cavernosa separate, bend sharply caudally, laterally, and dorsally, and follow the inferior borders of the inferior rami of the pubic bones.’
    • ‘Mandibular length refers to the distance between the posterior ramus and the inner mentum.’
    • ‘Sandwiched between the two jaw rami is the left splenial, which has become detached and has been displaced slightly dorsally.’
    • ‘The gland may extend to the mandibular ramus to cover the buccinator muscle.’
    1. 1.1 A major branch of a nerve.
      • ‘Note the ventral and dorsal rami of cervical spinal nerves.’
      • ‘A substantial portion of the nerve makes up its two communicating rami with the facial nerve; these are the strongest and most consistent of the many peripheral communications between trigeminal and facial nerves.’
      • ‘The intermediate and ulnar sets of muscles are supplied by branches from the deep ramus of the radial nerve after it has passed through the supinator muscle.’
  • 2Zoology
    A structure in an invertebrate that has the form of a projecting arm, typically one of two or more that are conjoined or adjacent.

    • ‘Branchiopod characters include endites with setae turned backwards, the elongation of the telson, and its fluke-shaped rami.’
    • ‘These include the presence of true, elongate furcal rami bearing spines in Perspicaris.’
    • ‘The rami of antenna 2 have between 12 and 19 articles.’
    1. 2.1 A barb of a feather.
      • ‘That is, the main shaft of the barb, the ramus, has a branching pattern of barbules.’
      • ‘Finger et al. and Andersson have documented that the structural UV hues of feather barbs, like other barb structural colors, are produced by the keratin air matrix of the spongy medullary layer of the barb ramus.’


Mid 17th century: from Latin, literally ‘branch’.