plane (plan)

1. A flat surface. See planum. 2. An imaginary surface formed by extension through any axis or two definite points in reference especially to craniometry and to pelvimetry. [L. planus, flat]
Addison's clinical p.'s a series of p.'s used as landmarks in thoracoabdominal topography; the trunk is divided vertically by a median p. from the upper border of the manubrium of the sternum to the pubic symphysis, by a lateral p. drawn vertically on either side through a point half way between the anterior superior iliac spine and the median p. at the interspinal p., and by an interspinal p. passing vertically through the anterior superior iliac spine on either side; transversely the trunk is divided by a transthoracic p. passing across the thorax 3.2 cm above the lower border of the body of the sternum, by a transpyloric p. midway between the jugular notch of the sternum and the pubic symphysis, corresponding to the disc between the first and second lumbar vertebrae, and by an intertubercular p. passing through the iliac tubercles and cutting usually the fifth lumbar vertebra; the p.'s formed on these lines, and also on transverse p.'s cutting the upper edge of the manubrium and the upper edge of the pubic symphysis, constitute the clinical p.'s of Addison.
Aeby's p. in craniometry, a p. perpendicular to the median p. of the cranium, cutting the nasion and the basion.
auriculo-infraorbital p. orbitomeatal p
axial p. transverse plane, as in CT scanning.transaxial p;
axiolabiolingual p. a p. parallel to the long axis of a tooth and extending in a labiolingual direction.
axiomesiodistal p. a p. parallel to the long axes of the teeth and extending in a mesiodistal direction.
bite p. occlusal p
Bolton p. a roentgenographic cephalometric p. extending from the Bolton point to nasion.Bolton-Broadbent p., Bolton-nasion line, Bolton-nasion p;
Bolton-Broadbent p. Bolton p
Bolton-nasion p. Bolton p
Broca's visual p. a p. drawn through the visual axes of each eye.
Camper's p. a p. running from the tip of the anterior nasal spine (acanthion) to the center of the bony external auditory meatus on the right and left sides.
canthomeatal p. p. passing through the two lateral angles of the eye and the center of the external acoustic meatus; this p. lies approximately midway between the Frankfort and the supraorbitomeatal p.'s.
coronal p. a vertical p. at right angles to a sagittal p., dividing the body into anterior and posterior portions.frontal p;
cove p. a classic description of terminal inversion of the electrocardiographic T wave with the initial portion arched above the baseline and the terminal portion below it, the former being rounded and the latter pointed.
datum p. an arbitrary p. used as a base from which to make craniometric measurements.
Daubenton's p. the p. of the foramen magnum. See also Daubenton's angle, Daubenton's line.
equatorial p. in metaphase of mitosis, the p. that touches all of the centromeres and their spindle attachments.
eye-ear p. orbitomeatal p
facial p. a measurement of the bony profile of the face.nasion-pogonion measurement;
first parallel pelvic p. superior pelvic aperture
fourth parallel pelvic p. inferior pelvic aperture
Frankfort p. orbitomeatal p
Frankfort horizontal p. orbitomeatal p
frontal p. coronal p
guide p. a fixed or removable device used to displace a single tooth, an arch segment, or an entire arch toward an improved relationship.
horizontal p. transverse p
p. of incidence the p. perpendicular to a lens surface that contains the incident light ray.
infraorbitomeatal p. orbitomeatal p
p. of inlet superior pelvic aperture
interspinal p. a horizontal plane passing through the anterior superior iliac spines; it marks the boundary between the lateral and umbilical regions superiorly and the inguinal and pubic regions inferiorly.planum interspinale [NA], Lanz's line;
intertubercular p. a horizontal plane passing through the iliac tubercles.planum intertuberculare [NA];
labiolingual p. a p. parallel to the labial and lingual surfaces of the teeth.
p. of least pelvic dimensions pelvic p. of least dimensions
mean foundation p. the mean of the various irregularities in form and inclination of the basal seat; the ideal condition for denture stability exists when the mean foundation p. is most nearly at right angles to the direction of force.
Meckel's p. a craniometric p. cutting the alveolar and the auricular points.
median p. a vertical p. through the midline of the body that divides the body into right and left halves. See also Addison's clinical p.'s.midsagittal p;
p. of midpelvis pelvic p. of least dimensions
midsagittal p. median p
Morton's p. a p. passing through the summits of the parietal and occipital protuberances.
nasion-postcondylar p. a p. passing through the nasion anteriorly and to a point immediately behind each condylar process of the mandible, posteriorly.
nodal p. the p. corresponding to the optical center of a simple lens. See nodal point.
nuchal p. the external surface of the squamous part of the occipital bone below the superior nuchal line, giving attachment to the muscles of the back of the neck.
occipital p. the external surface of the occipital bone above the superior nuchal line.planum occipitale;
occlusal p. , p. of occlusion an imaginary surface which is related anatomically to the cranium and which theoretically touches the incisal edges of the incisors and the tips of the occluding surfaces of the posterior teeth; it is not a p. in the true sense of the word but represents the mean of the curvature of the surface. See also curve of occlusion.bite p;
orbital p. the orbital surface of the maxilla, lying perpendicular to the orbitomeatal p. at the orbitale.planum orbitale;
orbitomeatal p. a standard craniometric reference p. passing through the right and left porion and the left orbitale; drawn on the profile radiograph or photograph from the superior margin of the acoustic meatus to the orbitale.auriculo-infraorbital p., eye-ear p., Frankfort horizontal p., Frankfort p., infraorbitomeatal p;
p. of outlet inferior pelvic aperture
parasagittal p. any p. parallel to the mid-sagittal p. or anteroposterior median p. See sagittal p.
p. of pelvic canal pelvic axis
pelvic p. of greatest dimensions the p. extending from the middle of the posterior surface of the pubic symphysis to the junction of the second and third sacral vertebrae, and laterally passing through the ischial bones over the middle of the acetabulum.second parallel pelvic p., wide p;
pelvic p. of inlet superior pelvic aperture
pelvic p. of least dimensions the p. that extends from the end of the sacrum to the inferior border of the pubic symphysis; it is bounded posteriorly by the end of the sacrum, laterally by the ischial spines, and anteriorly by the inferior border of the pubic symphysis.midplane, p. of least pelvic dimensions, p. of midpelvis, third parallel pelvic p;
pelvic p. of outlet inferior pelvic aperture
popliteal p. of femur popliteal surface of femur
principal p. the theoretic p. of a compound lens system. See principal point.
p.'s of reference p.'s which act as a guide to the location of other p.'s.
p. of regard an imaginary p. through which the point of regard moves as the eyes are turned from side to side.
sagittal p. originally (and strictly speaking) the sagittal plane is the median plane, and any other plane parallel to it is a parasagittal plane; in contemporary usage and in a broad sense, s. p. is used for any p. parallel to the median, i.e., as a synonym for parasagittal.
second parallel pelvic p. pelvic p. of greatest dimensions
spectacle p. the p. at which spectacles are worn.
sternal p. a p. indicated by the front surface of the sternum.planum sternale;
subcostal p. a horizontal plane passing through the inferior limits of the costal margin, i.e., the tenth costal cartilages; it marks the boundary between the hypochondriac and epigastric regions superiorly and the lateral and umbilical regions inferiorly.planum subcostale [NA], infracostal line;
supracrestal p. supracristal p
supracristal p. a horizontal plane passing through the summits of the iliac crests; it usually passes through the fourth lumbar spinous process.planum supracristale [NA], supracrestal p;
supraorbitomeatal p. a p. passing the superior orbital margins and the superior margin of the external acoustic meatuses; it makes an angle of approximately 25 to 30 degrees with the Frankfort p. and is the p. in which routine CT (computed tomography) scans of the brain are made.
suprasternal p. a horizontal p. passing through the body at the level of the superior margin of the manubrium of the sternum.
temporal p. a slightly depressed area on the side of the cranium, below the inferior temporal line, formed by the temporal and parietal bones, the greater wing of the sphenoid, and a part of the frontal bone.planum temporale;
third parallel pelvic p. pelvic p. of least dimensions
tooth p. any one of the imaginary p.'s of section of a tooth, such as the axial, horizontal, or vertical.
transaxial p. axial p
transpyloric p. a horizontal plane midway between the superior margins of the manubrium sterni and the symphysis pubis; the pylorus is not usually located on this plane in life.planum transpyloricum [NA];
transverse p. a p. across the body at right angles to the coronal and sagittal p.'s.horizontal p;
wide p. pelvic p. of greatest dimensions


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