WHAT ARE PNEUMATIC BONES? - BIOLOGY - 2025

The tires bones are those with air - filled cavities, making them lighter than the bones are completely solid. The word "tire" refers to the air contained under pressure, it is derived from the Greek and is related to the wind and the breath.

In biology, the term "tire" refers to respiration, which is why these bones are also known as "breathing bones" or "hollow bones." In birds, these types of bones offer an evolutionary advantage that has allowed them to fly thanks to their lightness.

The human facial bones are pneumatic, they are found around the inner eyebrow, under the eyes, around the nose and lower cheeks, they are the so-called paranasal sinuses.

These cavities of pneumatic bones are normally lined inside by a cellular layer called epithelium and are covered by mucosa.

In addition to making the skull lighter, it also contributes to sound resonance and it has been suggested that, together with the mucosa, it serves to condition the inspired air before it reaches the lungs.

The process of pneumatization of bones has been described in the skulls of mammals, birds and crocodiles, but it has also been documented in extinct animals such as dinosaurs and pterosaurs.

Functions of pneumatic bones

No single function has been defined for these hollow bones in nature. However, some hypotheses have been described about the role of these bones in the organisms that possess them:

Reduction in body mass

In pneumatic bones the cavities have been modified to contain air instead of medullary material, and consequently the body mass has been reduced.

This facilitated flight in birds and pterosaurs, as there is less mass but the same amount of muscle that powers flight.

Alteration of bone density

Pneumatization of the bones allows the redistribution of bone mass within the body. For example, a bird and a mammal of similar size have roughly the same bone mass.

However, bird bones can be denser because bone mass must be distributed in a smaller space.

This suggests that the pneumatization of the birds' bones does not affect the general mass, but promotes a better distribution of weight within the animal's body and, consequently, greater balance, agility and ease of flight.

Balance

In theropods (a suborder of dinosaurs), the skeletal system of the skull and neck was highly pneumatized, and the forearms were reduced. These adaptations helped decrease mass away from the center of gravity.

This adjustment to the center of mass allowed these animals to reduce rotational inertia, thus increasing their agility and balance.

Adaptation to heights

Birds that fly at high altitudes have anatomical adaptations that have allowed them to colonize these habitats. One of these adaptations has been precisely the extreme pneumatization of its skeleton.

References

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