from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun The lowest of the three major bones that constitute each half of the pelvis.
from The Century Dictionary.
- noun In anatomy, the posterior part of the pelvic arch in vertebrates, the lowermost of the three parts forming the os innominatum.
- noun In Crustacea, the third joint of the normally 7-jointed leg; the ischiopodite.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun anatomy The lowest of the three bones that make up each side of the
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun one of the three sections of the hipbone; situated below the ilium
from The American Heritage® Dictionary of the English Language, 4th Edition
At the level of a line extending from the lower part of the symphysis pubis to the spine of the ischium is a thickened whitish band in this upper layer of the diaphragmatic part of the pelvic fascia.
The ischium is the lowest and strongest portion of the bone; it proceeds downward from the acetabulum, expands into a large tuberosity, and then, curving forward, forms, with the pubis, a large aperture, the obturator foramen.
Posteriorly the ramus forms a large swelling, the tuberosity of the ischium, which is divided into two portions: a lower, rough, somewhat triangular part, and an upper, smooth, quadrilateral portion.
W. wattsi, which has a relatively small ilium and large blade-like ischium which is broad along its entire length.
When, therefore, dislocation takes place inward, the leg appears longer than natural, when compared with the other leg, for two reasons truly; for the bone which articulates with the hip-joint is carried from above down to the ischium where it rises up to the pubes, upon it, then, the head of the femur rests, and the neck of the femur is lodged in the cotyloid foramen (foramen thyroideum?).
The ischium is united to the great vertebra contiguous to the os sacrum by a cartilaginous ligament.
In all birds there is an ischium, but so placed and of such length that it would scarcely be taken for an ischium, but rather for a second thigh-bone; for it extends as far as to the middle of the belly.
For if its ischium extended but a short way from the fundament, and then immediately came the leg, as is the case in man and in quadrupeds, the bird would be unable to stand up at all.
As a remedy for this Nature has given them a long ischium, and brought it to the centre of the body, fixing it firmly; and she has placed the legs under this central point, that the weight on either side may be equally balanced, and standing or progression rendered possible.
In the pelvic girdle the ilium corresponds to the scapula, the ischium to the coracoid, the pubis to the clavicle.