ANATOMICAL PLANES AND AXES - ANATOMY AND PHYSIOLOGY - 2024

The anatomical planes and axes are imaginary surfaces that divide the human body to facilitate both the description of its structure and its name and study. The planes are two-dimensional imaginary surfaces, and the axes are imaginary one-dimensional cut lines.

The main characteristic that differentiates a plane from an axis is that a plane is two-dimensional, while an axis is one-dimensional.

Anatomic position

To understand anatomical planes and axes, one must initially understand what anatomical position is.

Anatomical position is about body position of reference, which was reached by consensus by anatomists to use the same terms for position and direction, and to understand descriptions of body anatomy universally.

This anatomical position is described as the human body in a standing position (standing), with horizontal view, upper limbs on each side and along the trunk, palms of the hands open forward and the lower limbs together, with the toes pointing forward.

From there it is understood that the patient can be in any position: lying on his back, lying on his stomach, lying on one side or sitting. The descriptions will always refer to the anatomical position described above.

Anatomical planes

The function of the anatomical planes is to serve as a spatial reference to facilitate the description and location of body organs and structures.

The anatomical planes mainly used for anatomical descriptions are three: sagittal or lateral, coronal or frontal, and horizontal, transverse or axial. However, there are bibliographies that admit a fourth plane: oblique.

- Sagittal or lateral plane

It is delimited by the high and deep dimensions.

It is a plane with vertical and anteroposterior direction; that is, it crosses the body's longitudinal axis and, therefore, divides it into a right half and a left half. These two halves are completely asymmetrical.

Sagittal plane. Edoarado / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

- Coronal or frontal plane

It is delimited by the height and width dimensions.

It is an equally vertical plane oriented transversely; that is, from right to left. Hence, it divides the human body into an anterior half and a posterior half.

Coronal plane. Edoarado / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

- Horizontal, transverse or axial plane

It is a transversal plane, perpendicular to the two previous ones, that divides the body into an upper half and a lower half.

Horizontal plane. Edoarado / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

- Oblique plane

It is delimited by the width and depth dimensions. Little used, it is a plane with a vertical direction, anteroposterior and from right to left or from left to right, which divides the human body into two oblique halves.

Oblique plane. Own image based on illustrations by Edoarado / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Body axes

In this anatomical context of description, the concept of axis refers to the point where an imaginary cut is made to establish the position and location of body structures.

Their function is to distinguish the distance or location of some organ or structure; for example, if one is medial (near the midline) or more lateral (away from the midline).

There are 3 types of axes: sagittal, longitudinal and transverse.

- Sagittal

It refers to the anteroposterior ventrodorsal axis; that is, it crosses the body from front to back, in a horizontal direction, and is perpendicular to the coronal planes.

- Longitudinal

Also called craniocaudal or superoinferior, it is vertical, like an arrow that passes through the body from the highest point of the skull towards the feet, passing through the body's center of gravity.

- Transverse

Also known as laterolateral, it has a horizontal direction. It goes from one side of the body to the other, perpendicular to the sagittal planes.

Anatomical terms of relationship

Once the anatomical planes and body axes have been established, it is important to know the anatomical terms of relation and comparison. These terms use planes and axes to make sense of the anatomical description and its relative location.

- Previous: that is ahead or in a previous position.

- Posterior: which is behind or dorsal.

- Superior: located above.

- Lower: located below.

- Cranial: closer to the skull, at the upper end of the trunk.

- Caudal: closer to the tail (cauda), lower end of the trunk.

- Medial: closer to the median sagittal plane.

- Proximal: located closer to the trunk or the point of origin.

- Distal: located further from the trunk or from the point of origin.

- Superficial: close to the surface.

- Deep: far from the surface.

- External: further from the center of an organ.

- Internal: close to the center of an organ.

- Axial: located on the sagittal axis.

- Ipsolateral: located on the same side.

- Contralateral: located in the opposite half of the body.

References

1. The Ruiz Liard Card. Human anatomy. 4th Edition. Volume 1. Editorial Médica Panamericana. General XIII-XV.
2. Courtney Smith. Anatomy and Physiology Anatomical planes and cavities. Oct, 13 of 2007. Recovered from: visiblebody.com
3. Anatomy body plans and sections. 07/01/2012. Recovered from: memorize.com
4. Oliver Jones. January 6, 2018. Anatomical plans. Recovered from: Teachmeanatomy.info
5. Kinetic Anatomy With Web Resource-3rd Edition. Human Kinetics. 2012. pp. 31