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To do this, distinct ends of an organism are chosen, and the axis is named according to those directions. An organism that is symmetrical on both sides has three main axes that intersect at right angles. [3] An organism that is round or not symmetrical may have different axes. [3] Example axes are: The anteroposterior axis [8] The cephalocaudal ...
The latter flexure mainly appears in mammals and sauropsids (reptiles and birds), whereas the other two, and principally the cephalic flexure, appear in all vertebrates (the sum of the cervical and cephalic ventral flexures is the cause of the 90-degree angle mentioned above in humans between body axis and brain axis).
The posterior semicircular canal contains the part of the vestibular system that detects rotation of the head around the antero-posterior (sagittal) axis, or in other words, rotation in the coronal plane. This occurs, for example, when one moves the head to touch the shoulders, or when doing a cartwheel (roll axis).
In the extremities, they are the rotation of the forearm or foot so that in the standard anatomical position the palm or sole is facing anteriorly when in supination and posteriorly when in pronation. [32] As an example, when a person is typing on a computer keyboard, their hands are pronated; when washing their face, they are supinated.
By means of the dissection of embryos followed by transplantation and rotation of the limb bud he demonstrated that the main axes of the developing limb are determined independently and at slightly different times, determination of the anteroposterior (anterior-posterior) axis preceding that of the dorsoventral (dorsal-ventral) axis.
The standard anatomical position, or standard anatomical model, is the scientifically agreed upon reference position for anatomical location terms.Standard anatomical positions are used to standardise the position of appendages of animals with respect to the main body of the organism.
The cortical rotation is powered by microtubules motors moving along parallel arrays of cortical microtubules. This gray crescent marks the future dorsal side of the embryo. Blocking this rotation prevents formation of the dorsal/ventral axis. By the late blastula stage, the Xenopus embryos have a clear dorsal/ventral axis.
The zeugopod consists of two parallel elements along the anteroposterior axis and the autopod contains three to five (in most cases) elements along the same axis. The digits also have a quasi-periodic arrangement along the proximodistal axis, consisting of tandem chains of skeletal elements.