Final answer:
The nasal septum is a rigid partition within the nasal cavity formed by the ethmoid bone, the vomer bone, and septal cartilage; it divides the cavity into two halves and contributes to air conditioning and pathogen filtration.
Step-by-step explanation:
The rigid partition composed of the ethmoid and vomer bones and cartilage is known as the nasal septum. This flat, midline structure divides the nasal cavity into halves and is crucial for supporting the structure of the nose and maintaining an open airway. The upper portion of the septum is formed by the perpendicular plate of the ethmoid bone, whereas the lower and posterior parts are formed by the vomer bone. The septal cartilage fills in the gap between these bones, extending forward to separate the right and left nostrils.
The ethmoid bone is a central element of the nasal cavity, contributing to the upper portion of the nasal septum, the roof, and lateral walls of the nasal cavity. The vomer bone shapes the lower part of the septum and can be better viewed from the posterior aspect of the nasal cavity. The septal cartilage ensures flexibility and completes the structure anteriorly, although it is not present in a dried skull. The entire assembly plays a vital role in not just dividing the nasal cavity, but also in conditioning air (warming and moisturizing) before it enters the lungs, and in helping to trap dust and pathogens in the nasal mucus.