rachis


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Related to rachis: petiolule

spine

 [spīn]
1. a thornlike process or projection; called also acantha and spina.
2. the rigid bony structure in the midline of the back, composed of the vertebrae; called also backbone, spinal column, and vertebral column.



The spinal column is the axis of the skeleton; the skull and limbs are in a sense appendages. The vertebrae also provide the protective bony corridor (spinal canal) through which the spinal cord passes; they can move to a certain extent and so give flexibility to the spine, allowing it to bend forward, sideways and, to a lesser extent, backward. In the areas of the neck and lower back, the spine also can pivot, which permits the turning of the head and torso.

There are usually 24 movable vertebrae and nine that are fused together. The topmost are the seven cervical vertebrae, which form the back of the neck, supporting the skull. The head turns from side to side by means of a pivotal motion between the two highest vertebrae. Below these are the 12 thoracic vertebrae, the supports on which the ribs are hinged, and then the five lumbar vertebrae, the largest movable vertebrae (the cervical are the smallest). Below the lumbar vertebrae, the spine terminates with two groups of vertebrae fused into single bones: the sacrum, composed of five vertebrae, and the coccyx, composed of four vertebrae. Viewed from the side of the body, the spine has the shape of a gentle double S curve.
Malformations of the Spine. Of the various types of spinal malformations, some are congenital and others the result of postural defects or injuries. spina bifida is congenital. kyphosis may occasionally be congenital but is more often caused by one of the diseases that attack the structure of the bones. The most common of these is pott's disease, or tuberculosis affecting the vertebrae and soft tissues of the spine. Another is osteitis deformans, a type of bone inflammation in which parts of the bone are replaced by softer tissue. scoliosis is a curvature of the spine toward one side.
cervical spine that portion of the spine comprising the cervical vertebrae.
lumbar spine that portion of the spine comprising the lumbar vertebrae.
thoracic spine that part of the spine comprising the thoracic vertebrae.

ver·te·bral col·umn

[TA]
the series of vertebrae that extend from the cranium to the coccyx, providing support and forming a flexible bony case for the spinal cord.

rachis

/ra·chis/ (ra´kis) vertebral column.

rachis

(rā′kĭs)
n. pl. rachises or rachides (răk′ĭ-dēz′, rā′kĭ-)
1.
a. The main stem of an elongated inflorescence, as in a grass.
b. The main axis of a pinnately compound leaf or of a fern frond.
2. The main shaft of a bird's feather, especially the part to which the barbs are attached.
3. The spinal column.

ra′chi·al adj.

ver·te·bral col·umn

(vĕr'tĕ-brăl kol'ŭm) [TA]
The series of vertebrae that extend from the cranium to the coccyx, providing support and forming a flexible bony case for the spinal cord.
Synonym(s): columna vertebralis [TA] , backbone, rachis, spina, spinal column, spine (2) .

rachis

or

rhacis

any central axis, particularly that of a feather.

rachis

1. the vertebral column.
2. the shaft of a feather.
References in periodicals archive ?
These berries appear similar to fruit with bunchstem necrosis, but the rachis look green and healthy.
Roots black, wiry; fronds pinnate-pinnatifid to bipinnate; rachis grooved; pinnate monomorhic or dimorphic; sori absent; sporangia on modified fertile segments of blades or separate fronds.
0 m long, rachis scales thick, subulate, terete, widely spreading; abaxial surfaces of rachises and costae with hairs 0.
An indeterminate rachis and extensive rhizomatous growth smother native understory vegetation and act as a fire ladder carrying low-intensity fires into the canopy, which causes extensive tree death (Pemberton & Ferriter 1998).
Le plus important c'est de bien choisir un praticien competant, specialise dans le rachis.
Then run the needle through the back of hole in the quilled strip that is on the same side of the rachis, but be sure to leave about V of the Nymo at the back of the feather.
Parmi eux, Kateb Yacine, Malek Haddad, Rachid Boudjedra, Tahar Ouatar, Rachis Mimouni.
tail - - - grains Triticum rachis 42 55 3 fragments Triticum glume 1459 1500 188 bases ** Cereal indet.
Shape of inflorescence, thickness of peduncle, venation of leaflet, and apex of floral bract (characters 10, 12, 9, and 13) were most important for determining the component score of the first axis; shape of rachis gland and length of leaflet (characters 3 and 7) were most important for determining the second axis, whereas the most important character for determination of the third axis was symmetry of stipular spine (character 1).
Elevation of high yielding hull-Less Barley varieties, an event in indian agriculture, Rachis, 2: 17-19.
distinctly exceeding the fascicles), inflorescence densely globose-capitate with the fascicles completely hiding the rachis (vs.