rachidian


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spinal

 [spi´nal]
1. pertaining to a spine.
2. pertaining to the vertebral column.
spinal cord that part of the central nervous system lodged in the spinal canal, extending from the foramen magnum to the upper part of the lumbar region. It is composed of an inner core of gray substance in which nerve cells predominate and an outer layer of white substance in which myelinated nerve fibers predominate. Called also medulla spinalis. (See Plates and see accompanying figures.)
Gross anatomy of the spinal cord. From Applegate, 2000.
Cross section of the spinal cord. From Applegate, 2000.

spi·nal

(spī'năl),
1. Relating to any spine or spinous process.
2. Relating to the vertebral column.
[L. spinalis]
References in periodicals archive ?
There are clearly five cusped teeth in each row, in contrast to the expected seven (rachidian, two pairs of laterals and the pluricuspid) as shown in previous illustrations for the species gordensis and densata, as originally illustrated by McLean (1990).
angulifera in that the cusp of rachidian is strongly dentate, with a sharply pointed central denticle and several similar but smaller lateral denticles on each side; laterals with a sharply pointed central cusp; marginals very numerous and fine.
2) and an increased length of rachidian and lateral teeth (indicated by rachidian and L3 in Fig.
Rachidian short, its cusp and base-plate more or less equal in length; inner lateral teeth more or less parallel-sided, tapering to a point at tip, increasing slightly in size from first to fifth or sixth; outer 2 or 3 laterals considerably larger, with a strong quadrate base-plate and well-developed curved cusp (length of cusp variable between individuals, frequently relatively stout); outer lateral tooth the largest.
Rachidian present, with a relatively short, broad cusp, one quarter to one third length of base-plate; remaining teeth (laterals and marginals), elongate and slender, progressively (slowly) increasing in size, those in middle of lateromarginal series largest, then decreasing in size somewhat more rapidly toward edge of radula, the outermost tooth being minute; inner teeth claw-like, with a relatively short, weakly curved, broadly acuminate cusp; larger teeth in middle of lateromarginal series with a flatter, more elongate cusp, but lacking an enlarged quadrate base-plate; those peripheral to this becoming spathulate, with a rounded tip and anteriorly acuminate base-plate.
Each row has a single, central, large rachidian tooth flanked by five lateral teeth, the most distal of which is large and has a sharp point, followed by numerous thin, filamentous marginal teeth along the outer edge (Fig.
anulatus is characterized by having a brown or white body with pink, white, and brown spots, smooth papillae epithelium at the base and papillated in the distal part of each papilla, unbranched digestive gland ducts within the dorsal papilla, smooth jaws, and smooth rachidian and lateral teeth.
Radulae of more than 100 genera of non-truncatellid rissooideans have been illustrated by various authors; all have a trapezoidal central (rachidian) tooth, as do geomelaniines [ILLUSTRATION FOR FIGURE 6B OMITTED].
Rachidian with seven rounded cusps, central one largest, the outermost pair small; occasionally with very small intermediary teeth between the larger ones.
The marginal teeth are long and fine, and naturally tend to fold inwards, overlapping each other and the central radula field, and thus obscuring the rachidian and lateral teeth.
Rachidian with broad, trigonal cusp and well-developed hood; cusp with strong transverse ridge at its base, this generally concave due to medial indentation near cusp base; cutting edge coarsely dentate, central denticle largest, lanceolate, with 2-4 smaller denticles on each side.