Forms Inferior Portion Of Nasal Septum

The Inferior Portion of the Nasal Septum: Anatomy, Function, and Clinical Significance

The nasal septum, a crucial cartilaginous and bony structure, divides the nasal cavity into two symmetrical halves. While the entire septum is vital for nasal function, its inferior portion, primarily composed of the quadrangular cartilage, plays a particularly significant role. This article delves into the intricate anatomy, physiological function, and clinical implications of the inferior portion of the nasal septum. We'll explore its complex interactions with surrounding structures, its contribution to airflow dynamics, and its susceptibility to various pathologies. Understanding this region is crucial for otolaryngologists, rhinologists, and other healthcare professionals involved in nasal surgery and diagnosis.

Anatomy of the Inferior Nasal Septum: A Detailed Look

The inferior portion of the nasal septum is primarily formed by the quadrangular cartilage, a thin, flexible plate of hyaline cartilage. This cartilage occupies the anterior and inferior part of the septum, extending from the bony septum superiorly and connecting to the medial crura of the greater alar cartilages inferiorly. Its anterior border is free, forming the anterior nasal spine, while its posterior border articulates with the vomer and perpendicular plate of the ethmoid bone.

Key Anatomical Relationships:

• Vomer: The inferior and posterior aspects of the quadrangular cartilage articulate with the vomer, a ploughshare-shaped bone forming the posterior part of the nasal septum. This articulation is crucial for maintaining the structural integrity of the septum.
• Perpendicular Plate of the Ethmoid Bone: Superiorly, the quadrangular cartilage connects with the perpendicular plate of the ethmoid bone, contributing to the superior stability of the septum.
• Maxilla: The inferior border of the quadrangular cartilage is closely associated with the maxilla, impacting the overall shape and position of the nasal tip.
• Greater Alar Cartilages: The medial crura of the greater alar cartilages attach to the inferior border of the quadrangular cartilage, providing crucial support and influencing the shape of the nostrils. Disruptions here can significantly impact nasal valve function.
• Septal Deviation: The quadrangular cartilage, being relatively flexible, is prone to deviation, a common condition where the septum is displaced from the midline. This deviation can occur congenitally or be acquired through trauma.

Blood Supply and Innervation:

The inferior nasal septum receives its blood supply primarily from branches of the sphenopalatine artery, anterior ethmoidal artery, and superior labial artery. This rich vascular network is clinically significant during septal surgery, requiring careful attention to minimize bleeding. Innervation is provided by branches of the trigeminal nerve, specifically the anterior ethmoidal nerve and the nasopalatine nerve, contributing to the sensory perception within the nasal cavity.

Physiological Function: The Role of the Inferior Septum in Airflow

The inferior portion of the nasal septum plays a pivotal role in nasal airflow dynamics. Its precise positioning and relationship with surrounding structures contribute significantly to:

1. Airflow Direction and Resistance:

A straight, well-positioned septum is crucial for directing airflow smoothly through the nasal passages. Deviation of the inferior septum can obstruct airflow, leading to increased resistance and altered airflow patterns. This can result in nasal congestion, difficulty breathing through the nose, and altered nasal resonance.

2. Nasal Valve Function:

The inferior portion of the septum interacts intimately with the anterior nasal valve, a critical area for regulating airflow. Any deviation or collapse of the inferior septum can compromise the patency of the nasal valve, leading to significant airflow restriction. This is a common cause of nasal obstruction and is often addressed surgically.

3. Humidification and Warming of Air:

The nasal septum, particularly its inferior portion due to its extensive surface area, facilitates the humidification and warming of inspired air. The extensive vascular network within the mucosa overlying the septum helps to transfer heat and moisture to the inhaled air, protecting the lower respiratory tract from dryness and cold.

4. Filtering of Air:

The nasal mucosa covering the inferior septum contains cilia and goblet cells that actively filter out dust, pollen, and other particulate matter from the inhaled air, protecting the lungs from irritants and pathogens.

Clinical Significance: Conditions Affecting the Inferior Septum

The inferior portion of the nasal septum is susceptible to a range of conditions, often requiring surgical intervention. Understanding these pathologies is vital for diagnosis and treatment.

1. Septal Deviation:

Septal deviation, as mentioned earlier, is a very common condition where the septum is displaced from the midline. This can be caused by congenital factors, trauma (e.g., nasal fractures), or even chronic inflammation. Symptoms can range from mild nasal congestion to severe breathing difficulties. Surgical correction, known as septoplasty, is often indicated for symptomatic septal deviation.

2. Septal Perforation:

Septal perforation is a hole in the nasal septum, often caused by trauma, surgery, or chronic inflammation. Symptoms can include whistling sounds during breathing, nasal dryness, and occasional nosebleeds (epistaxis). Treatment depends on the size and location of the perforation and may involve surgical repair or conservative management.

3. Septal Hematoma:

A septal hematoma is a collection of blood within the septum, usually caused by trauma. It's a surgical emergency due to the risk of septal abscess formation and cartilage necrosis (death of cartilage). Prompt drainage and antibiotics are typically required.

4. Septal Abscess:

A septal abscess is a localized infection within the septum, often a complication of a septal hematoma. Treatment involves surgical drainage and antibiotic therapy to prevent further damage to the cartilage.

5. Nasal Polyps:

Nasal polyps are benign growths in the nasal mucosa, often occurring near the inferior turbinate and potentially affecting the inferior septum. They can cause nasal congestion, loss of smell, and even facial pain. Treatment involves surgical removal or medical management.

Surgical Interventions: Addressing Inferior Septum Issues

Several surgical procedures target the inferior portion of the nasal septum to correct functional or aesthetic issues.

1. Septoplasty:

Septoplasty is the most common surgical procedure to correct septal deviation. It involves straightening the deviated septum to improve airflow. This procedure often involves careful manipulation and reshaping of the quadrangular cartilage.

2. Septorhinoplasty:

Septorhinoplasty combines septoplasty with rhinoplasty (nose reshaping) to address both functional and cosmetic concerns. It's frequently used to correct both septal deviation and nasal deformities.

3. Submucous Resection:

While less frequently performed now, submucous resection involves removing the deviated portion of the septum while preserving the overlying mucosa. This technique is now often superseded by septoplasty, which is considered less invasive.

Conclusion: The Unsung Hero of Nasal Function

The inferior portion of the nasal septum, while often overlooked, plays a critical role in nasal function. Its intricate anatomy and relationship with surrounding structures significantly impact airflow, humidification, and filtration. Understanding the anatomy, physiology, and clinical significance of this region is crucial for healthcare professionals involved in nasal diagnosis and surgery. The prevalence of conditions affecting the inferior septum highlights the importance of recognizing these issues and providing appropriate medical and surgical interventions to improve patients' quality of life. Further research into the complexities of this region will undoubtedly lead to improved diagnostic and therapeutic strategies in the future.