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 ?
Rachis browning is a common problem that affects grape quality and consumer preference.
The effect of relative humidity on resistance to abscission, which is a way to estimate the force with which the berries are attached to the rachis, was only affected at 0 days of shelf life (Figure 2C), whose response was represented by a parabola with maximum force at 92% relative humidity.
Christian Laurent, lead author of the study, said: "We started looking at the shape of the rachis and how it changes along the length of it to accommodate different stresses.
In CH40/91 mutants (Table 5), significant positive correlations were observed between plant height and rachis length (0.
Flowever, in terms the average number of flowers per rachilla in relation to their position on the rachis, there is no significant difference (Table 3).
The primary symptoms for this insect larval infestation on date palms are: presence of the insect larval frass (fecal excrement) on the young fronds, frond malformation, whitening of young leaves, "V" cut on leaf rachis, inflorescence axis and spathe, scratches, furrows and holes on the young fronds, and slight bend on the crown.
An Anatomical Study of Vascular System Spike: Distribution of Central and Peripheral Vascular Bundles along the Rachis of Wheat.
The oldest green leaf in the crown was sampled for each of the selected palms; mean values were calculated for the total length, sheath and petiole length, rachis length, and the number of pinnae on one side of the rachis; average mean values were calculated from samples of 3-6 pinnae taken in each of the medial, proximal and distal parts of the rachis, and from 3-4 largest spines on the sheath of each leaf.
12:00 Mufti of Lebanon Sheikh Mohammad Rachis Qabbani to receive at Dar Fatwa Swiss Ambassador
pineapple (Ananas comosus), bromeliads (Guzmania spp), banana (Musa spp), screw pine (Pandanus odoratissimus) and in the primary rachis of coconut (Cocos nucifera).
Inflorescence shortly paniculate, densely bipinnate, 22-30 cm long (including the terminal branch), 11-13 cm in diameter, erect, rachis nearly straight, green, glabrous, 0.