biology

Transpyloric plane

Transpyloric plane is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Transpyloric plane rather than just read about it. In short: The transpyloric plane, also known as Addison's plane, is an imaginary horizontal plane, located halfway between the suprasternal notch of the manubrium and the upper border of the symphysis pubis at the level of the first lumbar vertebra, L1. It lies roughly a hand's breadth beneath the xiphisternum or midway between the xiphisternum and the umbilicus.

Key takeaways

Transpyloric plane belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Transpyloric plane to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Transpyloric plane from memory before moving on to harder problems.

Reference excerpt

The transpyloric plane, also known as Addison's plane, is an imaginary horizontal plane, located halfway between the suprasternal notch of the manubrium and the upper border of the symphysis pubis at the level of the first lumbar vertebra, L1. It lies roughly a hand's breadth beneath the xiphisternum or midway between the xiphisternum and the umbilicus. The plane in most cases cuts through the pylorus of the stomach, the tips of the ninth costal cartilages and the lower border of the first lumbar vertebra.

Structures crossed The transpyloric plane is clinically notable because it passes through several important abdominal structures. It also divides the supracolic and infracolic compartments, with the liver, spleen and gastric fundus above it and the small intestine and colon below it.

Lumbar vertebra and spinal cord The lower border of first lumbar vertebra lies at the level of the transpyloric plane, according to Gray's Anatomy. Despite the conus medullaris, the end of the spinal cord, being understood to typically terminate at the level of the transpyloric plane, there is significant variability. Conversely, in the young child the cord is relatively longer and ends at the upper border of the third lumbar vertebra (subcostal plane). Due to biological variation, some adult people have spinal cords ending either above or below the transpyloric plane.

Stomach The transpyloric plane passes through the pylorus of the stomach, despite it being suspended by the lesser and greater omentum and being relatively mobile.

Duodenum The horizontal part of the duodenum slopes upwards to the left of the vertical midline, following which the vertical ascending part of the duodenum reaches the transpyloric plane. It ends in the duodenojejunal junction, which lies approximately 2.5 cm to the left of the midline and just below the transpyloric plane.

Pancreas The neck of pancreas lies on the transpyloric plane, whilst the body and tail are to the left and above it.

Gallbladder The fundus of the gallbladder projects from the liver's inferior border at the intersection of the transpyloric plane and the right lateral midline.

Kidneys Despite the right kidney lying 1 cm lower than the left (right just below and the left just above the plane), to be practical, the surface markings are taken the same way. The hilum of the kidney on the left and right is taken as 5 cm from the vertical midline and is on the transpyloric plane.

Vasculature The superior mesenteric artery arises from the aorta at the level of the transpyloric plane and emerges between the head and neck of the pancreas. The superior mesenteric vein is joined by the splenic vein to form the portal vein at the level of the transpyloric plane.

Spleen The lower border of the spleen lies near the transpyloric plane.

Other structures the left and right colic flexure the root of the transverse mesocolon. cisterna chyli (which drains into the thoracic duct).

History The transpyloric plane relates to the three-dimensional mapping of the abdomen founded on more than 10,000 measurements completed on 40 bodies, that surgeon Viscount Addison took at the turn of the 20th century. Addison reported his findings in a paper titled, "On the anatomical topography of the abdominal viscera in man, especially the gastro-intestinal canal" in which he established a baseline for the anatomy of the abdomen based on the arrangement of the map of the Earth. Using the suprasternal notch as the North Pole of the trunk, and the upper border of the pubic symphysis as the South Pole, he drew a vertical line joining these two points as his meridian. At the meridian's midpoint, he then drew a perpendicular line corresponding to the Equator. As this transverse plane crossed the pylorus, he called it the transpyloric plane.

Images

See also Interspinous plane Quadrants and regions of abdomen Subcostal plane Superior mesenteric artery Supracristal plane Transtubercular plane Transumbilical plane

References

This article incorporates text in the public domain from page 1315 of the 20th edition of Gray's Anatomy (1918)

External links Planes of the trunk.

Illustrations

Worked examples

Example 1 — a first encounter with Transpyloric plane

Start with the simplest possible case. Write down what Transpyloric plane claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Transpyloric plane before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Transpyloric plane ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Transpyloric plane

In research: Transpyloric plane appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Transpyloric plane in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Transpyloric plane is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anatomical planes, so understanding it makes those chapters shorter.
In everyday life: Look for Transpyloric plane outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Transpyloric plane in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Transpyloric plane means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Transpyloric plane out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Transpyloric plane in simple terms?

Why does Transpyloric plane matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Transpyloric plane?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Transpyloric plane.