Frame of reference in anatomy - SpeedyLook encyclopedia

In Anatomy, a frame of reference indicates the Terminologie used to locate or not in a precise way in the anatomical structure of a Organisme Humain. An anatomical frame of reference rests on a whole of Plan S and Axe S defined compared to the standard position of the organization described. For example, one uses this terminology to indicate the orientation of the Coupe S or the sights used in the diagrams and images in medicine or human Biologie starting from the position of Poirier , i.e. when the patient is upright vis-a-vis the observer.

Reference plans and axes

Median plane or sagittal plan

The median plane is the plan which separates the left half of the right half of the body. In any rigor, a sagittal plane is a plan parallel with the median plane but one uses also this expression to indicate the median plane itself which one then distinguishes from the para-sagittal plans located on the right or on the left of the median plane. One indicates also the median plane under the terms plan médiosagittal .

The areas located near the sagittal plan are known as median , the areas located remotely of this plan are known as side .

Bodies located of the same side of the median plane are known as ipsilatéraux while if they are located on both sides, it is said that they are in position contralatérale .

The bilateral Symétrie is characteristic of the Under-reign Bilateria among the multicellular animal .

Axial or transverse plan

An axial plan (or transverse) is a plan which separates the body in a part before (on the side of the Tête) and a back part (of with dimensions of the Queue). In human anatomy, the axial plans are horizontal and separate the body in an upper part (on the side of the head) and a lower part (on the side of the feet), this is why one meets sometimes the expression horizontal cut to indicate a cut in the axial plan.

Coronal plan or frontal

A coronal plan (or frontal) is a plan which separates the body in a part before and a back part. A seen dorsal is a sight which comes from the back, and a seen ventral is a sight which approaches the body by the ventral part.

Reference axes

The reference axes are definite Perpendiculaire lies in the datum-lines.

Dorso-ventral axis

The dorso-ventral axis is perpendicular to the coronaux plans. This axis is very early set up during the Embryogenèse as of the Fertilization. It corresponds thereafter to the organization of the paramount structures of the Tube neural and the gastro-intestinal Tube.

Rostro-caudal axis

The rostro-caudal axis is the axis perpendicular to the axial plans. It passes along the Spinal column at the vertebrate ones and more generally, at the animal with bilateral symmetry, this axis connects the oral opening (or Rostre) to the anal opening (on the side of the Queue, cauda in Latin). It corresponds to the second axis set up during the first stages of the Embryogenèse. For the majority of the animals, this axis is horizontal and is thus also called antéro-posterior axis. On the other hand, that is not the case at the bipeds for which the belly is ahead, this is why one prefers to use the rostro-caudal qualifier in order to avoid this ambiguity.

Center right-hand side-left

The axis right-hand side-left is defined like orthogonal in the median plane. The Brisure of symmetry which leads to the formation of the organization right-hand side-left of an organization also produces very early during embryogenesis. It conditions the Latéralisation internal bodies. The often asymptomatic condition of Situs inversus (or situs transversus ) appears by an inversion total or partial of the bodies compared to the median plane.

Human anatomy

Position of reference or position of Pear tree

It is always the position from which one studies the normal human body, at the adulthood, in vertical station the criteria are:

the alive subject in the position upright, vis-a-vis the observer;
the Leg S tended, the heel S plain and the Foot S in light external rotation (the slightly isolated point of the feet);
the glance with horizontal (plan of Frankfurt);
the hanging Arms along the body;
front armlevers and hands in supination (the Hand S opened, the Palm forwards, the Inch towards outside, others Finger S downwards pointing);
for the Man, the Penis at rest.

Because of Biped position of the human being, certain reference plans and axes do not have the same space orientation as in the anatomy of the other animals. For example, the rostro-caudal axis which represents the axis of the Spinal column Vertébré S is horizontal in the animals Quadrupède S, but vertical at the man and the other bipeds. Moreover, the orientation is made even more complicated by the fact that the Tête makes a Right angle with the remainder of the body, so that the ventral part of the Crâne is not turned forwards as for the remainder of the body but is not downwards turned. One thus defines a position of reference for the head according to which the Plan of Frankfurt is horizontal, i.e. the plan which passes by the lower edge of the ocular orbits and the higher edge of the canal auditory is parallel on the ground in this position of reference. That corresponds on a subject upright looking at right in front of him.

Medical imagery and conventions

Traditionally, the medical images are two-dimensional. They generally represent a cut (or the rebuilding of a virtual cut). It then poses the problem of knowing how the image obtained is presented, in particular if what is on the right on the image corresponds to the right part of the body or if, conversely the right part of the image represents the left part of the body. Indeed, because of bilateral symmetry, it is easy to confuse the right half and the left half of an organization.

For example, in the figure above, the frontal cut passes on the level of the arms. If one looks it of face, in other words in seen ventral , the right-hand side and the left are reversed: the right-hand man of the patient appears on the left of the image and, reciprocally, the left arm is on the right of the image. On the other hand, if one looks at this cut since the back, as if one placed oneself in his back, i.e in seen dorsal , then the left arm of the patient will appear on the left part of the image and the right-hand man on the right. The problem arises in a similar way for the transverse cuts.

One uses sometimes the following terminology to distinguish these various types of sights. Being the transverse cuts, one speaks about standard original for the cuts for top (where the right-hand side and the left are not reversed) and of standard Scanner whenever the cut is seen lower part (currently, mode more used in anatomy).

More generally, according to the radiological convention in Medical imagery, the right part of the organization is represented on the left of the image. By opposition, in neurological convention , the right-hand side and the left are not reversed on the image.

Specificities related to the cerebral imagery

One of the difficulties with respect to the medical imagery of the head at the human being is due to the fact that the Encéphale is not in the prolongation of the Rachis but form an angle so that, for example, the direction of the glance is horizontal when one is held upright. Consequently, which is ahead (former) is ventral for the remainder of the body but rostral (on the side of the nose and the mouth) being head. In the same way the ventral face of the brain corresponds to the lower part of this body. Only the median plane remains the same one for the head and the remainder of the body.

Consequently, an axial or horizontal cut of a human head will represent the plan defined by the rostrocaudaux axes and right-hand side-left whereas for the remainder of the body (or a head of a nonbiped animal), such a cut is defined by the dorsoventraux axes and right-hand side-left so that the axial cuts are parallel to the Lobe temporal at the man but perpendicular to the temporal lobe in an animal quadruped like the Rat (cf).

Qualifiers of orientation

Crânial or encephalic in direction of the head or quite simply superior.

Caudal towards the feet (inferior) (historically the anatomical nomenclature was used to describe the anatomy of the animals with four legs, therefore this qualifier indicated the direction of the tail (in opposition to the muzzle or to the nozzle (= rostral); at the Man the coccyx constitutes the vestige of this appendix and is thus the reference for the " term; caudal" ; one will not be able to thus apply this adjective to the elements of the pelvic member (and by extension of the thoracic member) for whom one will prefer " distal" and " proximal").

Side or external .

Médial or intern .

Median located on the line of centers of the body (axis cérébro-spinal) or a member.

Antérieur or ventral which looks at/is located forwards. Ventral indicates also the lower face of the Cerveau.

Postérieur or dorsal which looks at/is located backwards. Dorsal indicates also the back face of the hand, the higher face of the foot or the higher area of the brain located on the side of the top of the Crâne.

Palmar for the front face of the hand, the side of the Palm.

Plantar for the lower part of the foot, the side of the plant.

Proximal near to the root of a member.

Distal near to the end of a member.

References

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