Dictionary > Longitudinal section

Longitudinal section

Longitudinal section
n., plural: longitudinal sections
[ˌlɒndʒɪˈtjuːdɪnəl ˈsɛkʃən]
Definition: A section done by a plane along the long axis of a structure Image Modified by Maria Victoria Gonzaga of Biology Online from the work of CFCF, CC BY-SA 3.0

Longitudinal Section Definition

To describe the direction of movements and location of different body structures, a hypothetical plane is referred to as an anatomical plane that is used to transect the body. In the anatomy of animals and humans, three planes are used. Their brief description is as follows.

  1. Longitudinal section: This plane is parallel to the sagittal suture. It splits the body to the right and left. It is also named an anteroposterior or longitudinal plane.
  2. Coronal Section: This plane divides the body into dorsal and ventral or anterior-posterior parts. It is also referred to as the frontal or coronal plane and it shows the coronal view.
  3. Transverse Section: This plane divides the body into cranial and caudal parts, which means head and tail portion. It is also known as the horizontal plane.
anatomical planes of the human body
Figure 1: The different anatomical planes of the human body: coronal plane, transverse plane, and sagittal plane. The plane that runs vertically is the longitudinal plane. Legend:     Longitudinal plane,     Parasagittal plane,     Frontal or Coronal plane, and     Transverse or Axial plane. Image Credit: David Richfield and Mikael Häggström, M.D. and cmglee, CC BY-SA 4.0.

In the study of anatomical structures of plants and animals, the transverse and longitudinal sections are very important. The reason for the importance of the transverse and longitudinal planes is that they help to study the hidden organs and tissues of the body more openly and clearly. It is not possible to dissect the living animal or human transversely or longitudinally. So the dissection is done on dead bodies. They are cut into different planes or sections accordingly for detailed view and research.

Biology definition:
A longitudinal section is a section done by a plane along the long axis of a structure.  It pertains to a section done by a plane along the long axis of a structure in contrast to a cross-section, which refers to the transverse section. Longitudinal sections would, therefore, pertain to any vertical sections, such as median, sagittal, and coronal sections.

What is a longitudinal section?

The longitudinal section is defined as the section along the long axis of the structure. It is also related to the other vertical sections (median, coronal and sagittal). This section is done by a plane along the vertical axis of the body. The opposite of longitudinal is a cross-section.

Examples of a longitudinal section

Longitudinal sections can be one or more than one. The difference among them is the distance of the sections from the lateral end to the sectioning plane. Sagittal sections are obtained when the longitudinal section is made over the line of symmetry. It divides the body into symmetrical sections.

longitudinal axis plane of bone
Figure 2: longitudinal axis plane of bone.

An example of a longitudinal plane is a mid-coronal plane that divides a standing organism into two halves, either anterior-posterior or front back. The following image shows the longitudinal axis plane of bone.

 

Importance of longitudinal section

For a better understanding of structures and their physiology, the longitudinal view proves very useful and helpful. The nervous and digestive systems of elongated animals like snakes and worms can be studied easily through the longitudinal section.

Longitudinal section study also proves very helpful in the study of evolution. When the internal anatomical structures are compared with the fossil evidence, it helps to gain knowledge about evolutionary history. The dissection at the longitudinal section will help in understanding the cellular and tissue level organization of an organism.

The longitudinal section of skeletal muscle explains the organization and pattern of muscle fibers. It proves helpful in understanding the mechanism of muscle action and movement i.e. relaxation and contraction.

Transverse Section Definition

A transverse section is a cross-sectional part that is achieved by cutting the body or any part of the body structure in real or with help of imaging techniques in a horizontal plane. That plane crisscrosses the longitudinal axis at a 90-degree angle.

In the transverse plane (which is also known as horizontal or axial) segmenting results in the superior and inferior portions. In the anatomic transverse plane, the view of the segmented portion might be two dimensional, the superior side of the inferior portion of the inferior side of the superior portion
A transverse section divides the plane across the body of a plant, tissue, organ, or animal. Most of the time it is mentioned the division is between the left and right. Often, the transverse section tracks between the adjacent ends of a creature, from left to right. The section is made based on different heights or levels of a structure or an organ. Consequently, several transverse sections are created to analyze or observe the organ anatomy.

For example, a large number of different transverse cuts of brain scan results, which show the anatomical structure. It proves very helpful to analyzing and tracing any problem and disease in the brain. Ultrasound wave scan can help to study the anatomical organization at different levels, which shows that anatomy study of organs is possible with help of different transverse sections.

Generally, all the structures of plants and animals are not disclosed by the transverse section. The reason is that the tissues are formed in organs at different levels in an organism. Therefore, a small number of sections are made to comprehend the whole anatomy. In all animals, the alimentary tract is generally long, so transverse sections disclose the functions and anatomy of the alimentary tract at different levels such as secretory stomach, esophagus with secretion layers, toothed mouths, and absorbing guts, etc.

The transverse section and the longitudinal section are demonstrated in this video:

 

Difference between longitudinal section and transverse section

Here is a summary of the difference between the longitudinal section and the transverse section.

Table 1: Difference between longitudinal section and transverse section
Longitudinal section Transverse section
It runs through the anteroposterior axis. It goes between the lateral ends.
Longitudinal sections of biological specimens are most of the time longer than transverse sections. Transverse sections of biological specimens are most of the time smaller than longitudinal sections.
In an organ or an organism, the number of longitudinal sections is less. In an organ or an organism, the number of transverse sections is more.
The longitudinal section is right-angled to the transverse section. The transverse section is perpendicular to the longitudinal section.
Examples
The image shows the longitudinal cut. It is parallel to the longest length of the organ or specimen. (MedSci, 2006)

longitudinal cut of an organ

A cut in the transverse section. It is perpendicular to the main plane of the organ or specimen. (MedSci, 2006)

transverse section

The brain is cut in half through the midsection. It shows the longitudinal section anatomy of the brain. (Naveen, 2013)

longitudinal section of brain

The brain is viewed from the lower side. This is an example of a transverse plane. (Naveen, 2013)

transverse section of brain

 

Uses of Anatomical Planes and Sections

  • Motion: To explain motions and movements, these planes and sections prove very helpful. When movement is in the transverse plane, it is from head to the toe. For example, if a person is jumping up and down, his body is moving in a transverse plane.
  • Medical imaging: In different medical imaging techniques like PET scans, CT scans, MRI scans, and sonography, these planes prove helpful in explaining the orientation of tissues, organs, or body parts.
  • Finding anatomical landmarks. In human beings, anatomical landmarks which are visible on skin or present underneath, are used as a reference for explaining the superficial anatomy. In the spine, references are also made at specific levels. While performing abdominal surgeries, references are also made according to these planes and sections.

References

  • MedSci. (2006). http://medsci.indiana.edu/histo/docs/stn8.htm. Retrieved 09 05, 2021 from MdSci.
  • Naveen. (2013, 05 25). Difference Between Longitudinal and Transverse Section. Retrieved 09 04, 2021 from Differencebetween: https://www.differencebetween.com/difference-between-longitudinal-and-vs-transverse-section/
  • Rad, A., & Mytilinaios, D. (2021, 07). Cross sectional anatomy. Retrieved 09 05, 2021 from kenhub: https://www.kenhub.com/en/library/anatomy/cross-sectional-anatomy

 

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