diameter


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diameter

 [di-am´ĕ-ter]
the length of a straight line passing through the center of a circle and connecting opposite points on its circumference; hence the distance between the two specified opposite points on the periphery of a structure such as the cranium or pelvis.
cranial d's (craniometric d's) imaginary lines connecting points on opposite surfaces of the cranium; the most important are biparietal, that joining the parietal eminences; bitemporal, that joining the extremities of the coronal suture; cervicobregmatic, that joining the center of the anterior fontanel and the junction of the neck with the floor of the mouth; frontomental, that joining the forehead and chin; occipitofrontal, that joining the external occipital protuberance and the most prominent midpoint of the frontal bone; occipitomental, that joining the external occipital protuberance and the most prominent midpoint of the chin; suboccipitobregmatic, that joining the lowest posterior point of the occiput and the center of the anterior fontanel.
pelvic diameter see pelvic diameter.

di·am·e·ter

(dī-am'ĕ-tĕr),
1. A straight line connecting two opposite points on the surface of a more or less spheric or cylindric body, or at the boundary of an opening or foramen, passing through the center of such body or opening.
2. The distance measured along such a line.
[G. diametros, fr. dia, through, + metron, measure]

diameter

/di·am·e·ter/ (di-am´ĕ-ter) the length of a straight line passing through the center of a circle and connecting opposite points on its circumference. Symbol d.
anteroposterior diameter  the distance between two points located on the anterior and posterior aspects, respectively, of the structure being measured, such as the true conjugate diameter of the pelvis or occipitofrontal diameter of the skull.
Baudelocque's diameter  external conjugate d.; see pelvic d.
conjugate diameter  see pelvic d.
cranial diameters  distances measured between certain landmarks of the skull, such as biparietal, that between the two parietal eminences; bitemporal, that between the two extremities of the coronal suture; cervicobregmatic, that between the center of the anterior fontanel and the junction of the neck with the floor of the mouth; frontomental, that between the forehead and chin; occipitofrontal, that between the external occipital protuberance and most prominent midpoint of the frontal bone; occipitomental, that between the external occipital protuberance and the most prominent midpoint of the chin; suboccipitobregmatic, that between the lowest posterior point of the occiput and the center of the anterior fontanel.
pelvic diameter  any diameter of the pelvis, such as diagonal conjugate, joining the posterior surface of the pubis to the tip of the sacral promontory; external conjugate, joining the depression under the last lumbar spine to the upper margin of the pubis; true (internal) conjugate, the anteroposterior diameter of the pelvic inlet, measured from the upper margin of the pubic symphysis to the sacrovertebral angle; oblique, joining one sacroiliac articulation to the iliopubic eminence of the other side; transverse (of inlet), joining the two most widely separated points of the pelvic inlet; transverse (of outlet), joining the medial surfaces of the ischial tuberosities.
Enlarge picture
Diameters of pelvic inlet (see also pelvic planes ).

diameter (D)

[dī·am′ə·tər]
Etymology: Gk, diametros
1 the length of a straight line passing through the center of a circle and connecting opposite points on its circumference.
2 the distance between two specified opposite points on the periphery of a structure such as the cranium or pelvis.

di·am·e·ter

(dī-am'ĕ-tĕr)
1. A straight line connecting two opposite points on the surface of a more or less spheric or cylindric body, or at the boundary of an opening or foramen, passing through the center of such body or opening.
2. The distance measured along such a line.
[G. diametros, fr. dia, through, + metron, measure]

diameter

the length of a straight line passing through the center of a circle and connecting opposite points on its circumference; hence the distance between the two specified opposite points on the periphery of a structure such as the cranium or pelvis.

cranial d's, craniometric d's
imaginary lines connecting points on opposite surfaces of the cranium.
pelvic diameter
any of the diameters of the pelvis; any measurement that expresses the diameter of the birth canal in the female.
References in classic literature ?
We had excavated the entire circle of four feet diameter, and now we slightly enlarged the limit, and went to the farther depth of two feet.
The car, which was of a circular form and fifteen feet in diameter, was made of wicker-work, strengthened with a slight covering of iron, and protected below by a system of elastic springs, to deaden the shock of collision.
He joined to these a spiral, two inches in diameter, which terminated in two branch pieces of unequal length, the longer of which, however, was twenty-five feet in height and the shorter only fifteen feet.
In the window opening he set small branches about an inch in diameter both vertically and horizontally, and so woven that they formed a substantial grating that could withstand the strength of a powerful animal.
Just ahead of him in the roof of the aqueduct was a round, black hole about thirty inches in diameter.
Tegetmeier, I separated two combs, and put between them a long, thick, square strip of wax: the bees instantly began to excavate minute circular pits in it; and as they deepened these little pits, they made them wider and wider until they were converted into shallow basins, appearing to the eye perfectly true or parts of a sphere, and of about the diameter of a cell.
The diameter of the whole tube was nearly equal, and therefore we must suppose that originally it extended to a much greater depth.
There also I have found, in considerable quantities, curious balls, composed apparently of fine grass or roots, of pipewort perhaps, from half an inch to four inches in diameter, and perfectly spherical.
I'm not tied down to anything that isn't 8,000 miles in diameter.
There was the mainmast, fifteen inches in diameter at what was now the butt, still sixty-five feet in length, and weighing, I roughly calculated, at least three thousand pounds.
At length I found out an experiment for that also, which was this: I made some earthen-vessels very broad but not deep, that is to say, about two feet diameter, and not above nine inches deep.
100), and the other a figure having one side equal to the former, but oblong, consisting of a hundred numbers squared upon rational diameters of a square (i.