Shape

Shape of the Lungs

The lungs are funnel, conical, or even pyramidal in shape, with a narrow apex and a broad, concave base.

There are two major functional components to the lungs; the transport system and the exchange system. The first image is a reformatted image in the coronal plane which reveals the transport system of the lungs. The second image is a surface rendering of the lungs which reveals the parenchymal component which functions as the gas exchange system. The tree like features of the lungs is exemplified by an infrastructure of dividing branches which subserve the leaves – in essence a tubular system serving the factories of gas exchange.
Ashley Davidoff TheCommonVein.net 32634d02 32634b02

Pyramidal Shape of the Lungs in Nature
Two leaves of the coleus plant, with a pyramidal or conical shape that reminded the photographer of a set of lungs. The branching system originates from the hilum of the leaf almost at its center, but unlike the tracheobronchial tree it is not irregularly dichotomous.
Ashley Davidoff TheCommonVein.net . 42643

Together within the thoracic cage, the lungs may be viewed as an inverted wine glass with the stem of the cup representing the neck and the glass itself the chest. It is the shoulders that are added to the chest that give the sense of the breadth of the chest and the term “broad-chested” is in fact more accurately broad shouldered.

The Inverted Chest – A Wineglass
Ashley Davidoff TheCommonVein.net . 22071b01.800

The apex, also called the cupola is dome shaped, fitting snuggly into the space created by the soft tissue confluence of the mediastinal parietal pleura with the costal parietal pleura and the bony frame formed by the clavicle and first rib. It is positioned 2-3cm superior to the medial third of the clavicle where it projects through the superior thoracic inlet.

Cupola – shape of the apex
This cupola or dome was photographed in the church of the Villa Melzi gardens in Bellagio, Italy. If you imagine yourself in the chest cavity and you look up towards the neck, this is what you will see – the dome shaped structure of the apex of the lung and pleura.
Ashley Davidoff TheCommonVein.net 78115pb01

Lung parenchyma is relatively exposed at the apex making it vulnerable to penetrating injuries of the neck.

The base of the lung is concave so that there is a snug fit with the hemi diaphragms bilaterally. An intimate and parallel contact is maintained during all phases of respiration. This contact is necessary since the function of these two structures is intimately linked. The shape of the base will of course change with respiration and, like two dancers doing the tango, the diaphragm and lung move gracefully, intimately, and sometimes dramatically together with each phase of respiration – even with the sharp turn of events of a hiccup or a cough (or the tango equivalents – the gancho or the giro!).

Each lobe of the lungs has a characteristic shape, and may look very different in the A-P projection and lateral projection.. The RUL is roughly triangular in shape but with blunted or rounded angles. It’s A-P shape is very similar to its lateral shape. The RML and the RLL are both rectangular in the A-P projection but triangular in the lateral view, (apex at hilum and base anteriorly), though the RML is comparatively smaller.

Right lung – shapes of the lobes
These images (left to right) show the shapes of the RUL, RML and RLL. In Fig 1a and 1b the overlay represents the upper lobe. Image 2a and 2b represent the middle lobe while in 3a and 3b the lower lobe is represented. Note how the middle lobe hugs the right heart border and how much larger the RLL is compared to the RML and the RUL.
Ashley Davidoff TheCommonVein.net 30398c01
Ashley Davidoff MD

Left Lung – Shapes of the Lobes
In left sided images (top and bottom on the left), the overlay represents the upper lobe and lingula. Note how the lingula hugs the left heart border. The top and bottom on the right represent the left lower lobe. The volume of the LUL and LLL is about equal. Courtesy Ashley Davidoff MD. 30398c02.8

The LUL from the A-P projection resembles a rectangle with the upper edge being rounded, while from the lateral view it is shaped like half an oval, the bottom part being pointed. The LLL, from the A-P projection, is almost a perfect rectangle, and from the lateral view is almost a perfect triangle.

Applied Anatomy

In a hyperinflated state such as exists in emphysema, the lungs are full, bulging with air, and less pliant, causing the diaphragm to flatten. Clinically, the patient is described as having a barrel shaped chest, a pigeon shaped chest, or in Latin pectus carinatum. The CXR in this circumstance will show flattened hemi diaphragms, reflecting the almost fixed shape of the lungs, and an increase in the air space behind the sternum, (the retrosternal air space) which causes the barrel shape described above.