The term “septum” refers to a dividing wall or partition that separates two chambers or masses of soft tissue. While septa are found throughout the human body, their size and integrity are particularly important in the nose and the heart. The normal size of a septum is defined by its shape, alignment, and thickness, which directly affect its function in separating spaces and regulating flow. Understanding what constitutes a normal septum is essential because deviations from this norm can significantly impact breathing and cardiovascular health.
Understanding the Nasal Septum
The nasal septum is the wall composed of bone and cartilage that divides the nasal cavity into two separate passages. It is formed by the perpendicular plate of the ethmoid bone, the vomer, and the quadrangular cartilage, providing both structure and flexibility. For the nasal septum, “normal size” is defined by its straightness and central alignment rather than a specific thickness. A perfectly straight septum is uncommon, as studies suggest a minor degree of misalignment is present in approximately 80% of the population.
This minor displacement is considered normal if it does not restrict the passage of air or cause noticeable symptoms. A deviated septum occurs when the displacement is significant enough to cause a partial or complete obstruction of one or both nasal passages. This deviation can lead to symptoms such as chronic nasal congestion, frequent nosebleeds, or difficulty breathing. The septum’s primary role is to maintain symmetry, which is the measure of its normal function.
The Cardiac Septa and Normal Thickness
The heart contains two primary septa: the interatrial septum (IAS) and the interventricular septum (IVS), which separate the four chambers. For these partitions, “normal size” requires adequate thickness and complete integrity, meaning an absence of holes or gaps. The IVS is a thick, muscular wall separating the two lower pumping chambers (ventricles) and is structurally much more substantial than the IAS. The normal thickness of the IVS, measured at the end of the heart’s resting phase (end-diastole), typically falls within the range of 6 mm to 10 mm (0.6 cm to 1.0 cm) in healthy adults.
This thickness is necessary to withstand the high pressures generated by the left ventricle as it pumps blood out to the body. In contrast, the interatrial septum, which separates the two upper receiving chambers (atria), is considerably thinner. The IAS is not uniformly thick; the central portion, known as the fossa ovalis, is the thinnest, sometimes measuring as little as 0.4 mm in healthy adults. Other regions of the IAS are slightly thicker, often measuring around 2 mm to 3 mm.
Normal integrity is defined by the absence of abnormal openings. An abnormal size is often characterized by a defect, such as a Ventricular Septal Defect (VSD) in the IVS or an Atrial Septal Defect (ASD) in the IAS. The presence of a VSD or ASD allows blood to shunt between chambers, disrupting the heart’s normal, one-way flow. For example, a septal defect larger than 8 mm to 10 mm may be considered a large defect requiring medical intervention.
How Septal Measurements Are Assessed
The methods used to assess septa are specific to their location, focusing on alignment for the nose and thickness for the heart. Nasal septum assessment begins with a physical examination, where a physician uses a rhinoscope to visualize the septum’s alignment and the degree of obstruction. For a more detailed structural analysis, especially to evaluate the underlying bone and cartilage, computed tomography (CT) scans provide a clear, cross-sectional image of the nasal passages.
The cardiac septa are primarily assessed using echocardiography, an ultrasound of the heart. This non-invasive tool provides real-time moving images, allowing clinicians to accurately measure the thickness of the IVS and IAS and visualize wall integrity. Echocardiography is highly effective for determining if a congenital defect, such as an ASD or VSD, is present and for precisely measuring its size. These measurements guide clinical decisions regarding whether a nasal deviation requires surgical correction or if a cardiac septal defect necessitates monitoring or intervention.