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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.


1. Relating to any spine or spinous process.
2. Relating to the vertebral column.
[L. spinalis]


/ra·chid·i·an/ (rah-kid´e-an) spinal (1).

rachidial, rachidian

pertaining to the spine.
References in periodicals archive ?
The shafts of the rachidian and inner pair of lateral are narrow; the cusp of the second pair is larger than that of the first pair; the shaft of the second pair is hidden behind the larger pluricuspid.
The cusps have a rounded edge, unlike the square rachidian of Paralepetopsis floridensis and the acutely pointed outline of the other cusps of P.
The rachidian cusp is generally well developed and the lateral flanges on its upper shaft expanded to create a hood of variable extent.
The cusp of the innermost lateral is usually similar in size or slightly larger than that of the rachidian, with those of the remaining laterals being similar in size or progressively decreasing slightly in size (rarely the reverse).
5 mm SL contained the rachidian tooth (R), 2 pairs of lateral teeth (L1 and L2), and 2 to 3 pairs of marginal teeth per row (Fig.
The serrations on the working edges of the rachidian and lateral teeth became less pronounced as abalone grew.
Rachidian with well-developed hood and narrowly trigonal cusp; cusp with small medial indentation near its base; cutting edge with a dominant, lanceolate central denticle, with 2 or 3 smaller denticles on each side.
cretaceus differs in having a narrower, acutely trigonal rachidian cusp and inner marginals that lack a strongly pectinate outer margin.
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.
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.