Sphenopalatine artery

The sphenopalatine artery is a terminal branch of the maxillary artery, which is itself a branch of the external carotid artery. It plays a crucial role in supplying blood to the nasal cavity and the paranasal sinuses.

Location

The sphenopalatine artery arises from the maxillary artery in the pterygopalatine fossa, a small space behind the maxilla. From here, it passes through the sphenopalatine foramen, a small opening in the lateral wall of the nasal cavity, to enter the nasal cavity. Once inside the nasal cavity, the sphenopalatine artery divides into several branches, supplying the posterior and superior parts of the nasal septum and lateral nasal wall. It also provides blood to the paranasal sinuses, including the sphenoid and ethmoid sinuses, and contributes to the vascularization of the Kiesselbach’s plexus, a common site for nosebleeds (epistaxis).

Anatomy

The sphenopalatine artery is a terminal branch of the maxillary artery and is one of the main arteries supplying the nasal cavity and paranasal sinuses. It plays a significant role in the vascularization of the nasal structures, with its complex branching pattern providing blood to various areas within the nasal cavity. Below is a detailed description of the anatomy of the sphenopalatine artery.

Origin

The sphenopalatine artery arises from the maxillary artery, which itself is a branch of the external carotid artery. The maxillary artery courses through the infratemporal fossa and into the pterygopalatine fossa, where it gives rise to several branches, including the sphenopalatine artery. The sphenopalatine artery represents the terminal branch of the maxillary artery.

Course

In the Pterygopalatine Fossa:

After branching off from the maxillary artery within the pterygopalatine fossa, the sphenopalatine artery passes medially toward the nasal cavity. The pterygopalatine fossa is a small, pyramidal-shaped space located behind the maxilla, bounded by the sphenoid and palatine bones.
Within this fossa, the artery travels toward the sphenopalatine foramen, an important opening that serves as the gateway for the artery to enter the nasal cavity.

Passage Through the Sphenopalatine Foramen:

The sphenopalatine artery enters the nasal cavity through the sphenopalatine foramen, a bony opening located at the posterior part of the lateral nasal wall. This foramen is found at the junction between the sphenoid bone and the palatine bone.
The sphenopalatine foramen allows the artery to exit the pterygopalatine fossa and enter the nasal cavity, where it immediately begins to divide into several branches that supply different regions of the nasal cavity and paranasal sinuses.

Branches

Posterior Septal Branches:

One of the most important branches of the sphenopalatine artery is the posterior septal branch, which supplies the nasal septum. This branch runs along the posterior and superior portions of the nasal septum, providing blood to the mucosa and contributing to the overall vascularization of the nasal cavity.
The posterior septal branch anastomoses with the branches of the greater palatine artery and the anterior ethmoidal artery, helping form an extensive vascular network in the nasal septum.

Posterior Lateral Nasal Branches:

The sphenopalatine artery also gives off posterior lateral nasal branches, which supply the lateral wall of the nasal cavity.^[8] These branches provide blood to the turbinates (conchae) and the mucosa of the lateral nasal wall, ensuring that these structures remain well-nourished and functional.
The posterior lateral nasal branches also contribute to the vascularization of the paranasal sinuses, particularly the sphenoid and ethmoid sinuses.

Paranasal Sinus Branches: In addition to supplying the nasal cavity, the sphenopalatine artery sends smaller branches to the paranasal sinuses, specifically the sphenoid sinus and the posterior ethmoidal air cells. These branches ensure that the mucosal lining of the sinuses remains well-vascularized, supporting their role in humidifying and filtering inhaled air.

Anastomoses

Anastomosis with the Greater Palatine Artery: One of the most important anastomoses of the sphenopalatine artery is with the greater palatine artery. This artery arises from the descending palatine artery, another branch of the maxillary artery. The anastomosis between the posterior septal branch of the sphenopalatine artery and the greater palatine artery occurs in the nasal septum, creating a robust blood supply to this region.
Anastomosis with the Anterior Ethmoidal Artery: The sphenopalatine artery also forms anastomoses with the anterior ethmoidal artery, a branch of the ophthalmic artery. This connection occurs within the nasal cavity and contributes to the extensive vascular network in the region. The anterior ethmoidal artery supplies the anterior and superior parts of the nasal cavity, while the sphenopalatine artery supplies the posterior and inferior parts.
Kiesselbach’s Plexus (Little’s Area): One of the most clinically important sites where the sphenopalatine artery forms anastomoses is at Kiesselbach’s plexus, also known as Little’s area. This is a highly vascular region located on the anterior part of the nasal septum, where several arteries, including branches of the sphenopalatine artery, converge. This area is prone to bleeding and is a common site for epistaxis (nosebleeds).

Relations of the Sphenopalatine Artery

Maxillary Nerve and Pterygopalatine Ganglion: Within the pterygopalatine fossa, the sphenopalatine artery is closely related to the maxillary nerve (V2), a branch of the trigeminal nerve, and the pterygopalatine ganglion. These structures are located in close proximity to the artery and are important in transmitting sensory and autonomic signals to the nasal cavity and palate.
Nasal Mucosa and Turbinates: As it enters the nasal cavity through the sphenopalatine foramen, the sphenopalatine artery becomes closely associated with the nasal mucosa and the turbinates (conchae), which are bony structures on the lateral nasal wall. The artery’s branches supply these mucosal tissues and help maintain their function in humidifying and filtering air.
Sphenoid and Ethmoid Sinuses: The sphenopalatine artery also has a close anatomical relationship with the sphenoid and ethmoid sinuses, as it provides vascular branches to these areas. These paranasal sinuses are located near the posterior part of the nasal cavity, where the artery enters through the sphenopalatine foramen.

Termination

The sphenopalatine artery terminates by dividing into its main branches, which supply the nasal septum, lateral nasal wall, and paranasal sinuses. These branches form extensive anastomoses with other arteries in the nasal cavity, ensuring a rich blood supply to the entire region. In summary, the sphenopalatine artery is a terminal branch of the maxillary artery that supplies the posterior and superior parts of the nasal cavity, including the septum, lateral wall, and paranasal sinuses.^[7] It enters the nasal cavity through the sphenopalatine foramen and forms anastomoses with other arteries, including the greater palatine and anterior ethmoidal arteries, contributing to the extensive vascular network of the nasal cavity. Its branches supply blood to key nasal structures, making it a critical vessel in the anatomy of the nose and sinuses.

Function

The sphenopalatine artery plays a crucial role in supplying blood to the nasal cavity, paranasal sinuses, and associated structures.^[6] It is the main artery responsible for the vascularization of the posterior nasal region, ensuring the health and function of the nasal mucosa, sinuses, and turbinates. Below is a detailed explanation of the various functions of the sphenopalatine artery.

Blood Supply to the Nasal Septum

Nourishment of the Posterior Nasal Septum

The sphenopalatine artery’s posterior septal branch supplies blood to the nasal septum, particularly the posterior and superior portions. The septum divides the nasal cavity into two halves, and its mucosal lining is highly vascularized to warm, humidify, and filter inhaled air.
By providing blood to the septal mucosa, the sphenopalatine artery ensures that the nasal septum remains healthy and capable of performing its functions, including the regulation of airflow and support for olfactory functions.

Contribution to the Nasal Vascular Network: The sphenopalatine artery forms anastomoses with other arteries, such as the greater palatine artery and anterior ethmoidal artery, contributing to the rich vascular network of the nasal septum.^[5] These connections help ensure that blood flow remains consistent even if one vessel is compromised, maintaining the health of the septal mucosa.

Blood Supply to the Lateral Nasal Wall

Vascularization of the Turbinates (Conchae)

The sphenopalatine artery’s posterior lateral nasal branches supply the lateral wall of the nasal cavity, including the turbinates (conchae). These bony structures are covered by a mucosal lining and play an important role in humidifying, warming, and filtering the air we breathe.
The artery’s blood supply to the turbinates supports their function by ensuring that the mucosa remains moist and capable of trapping dust and pathogens. This process is essential for maintaining the cleanliness and health of the airways.

Support for Nasal Mucosal Health The sphenopalatine artery provides the necessary blood flow to the mucosal lining of the lateral nasal wall. This mucosa produces mucus, which helps trap inhaled particles and pathogens, preventing them from entering the respiratory tract. The artery’s blood supply ensures that this protective layer remains functional and healthy.

Blood Supply to the Paranasal Sinuses

Vascularization of the Sphenoid Sinus

The sphenopalatine artery supplies blood to the sphenoid sinus, a large air-filled cavity located in the body of the sphenoid bone. The sinus plays a role in humidifying and warming the air, as well as contributing to the voice's resonance.
The artery’s branches ensure that the mucosal lining of the sphenoid sinus receives enough blood to maintain its function, including the production of mucus and the filtration of inhaled air.

Vascularization of the Ethmoidal Sinuses

The sphenopalatine artery also provides blood to the posterior ethmoidal sinuses, which are located within the ethmoid bone.^[4] Like the sphenoid sinus, the ethmoidal sinuses help in air humidification and contribute to the resonance of the voice.
The artery’s branches ensure that the mucosa of the ethmoidal sinuses is adequately supplied with oxygenated blood, supporting their role in respiratory health and protecting the body from infections.

Contribution to the Nasal Blood Supply Network

Anastomosis at Kiesselbach’s Plexus (Little’s Area)

One of the most clinically significant functions of the sphenopalatine artery is its contribution to Kiesselbach’s plexus, also known as Little’s area, located on the anterior part of the nasal septum. This area is the site where multiple arteries, including branches of the sphenopalatine artery, converge.
This vascular convergence creates a highly vascularized region that plays a role in regulating nasal blood flow. It is also a common site for epistaxis (nosebleeds) due to the dense network of vessels.

Support for Collateral Circulation The sphenopalatine artery forms important anastomoses with other arteries, such as the greater palatine artery and the anterior ethmoidal artery.^[3] These connections create collateral pathways for blood flow, ensuring that the nasal cavity and sinuses receive an uninterrupted blood supply even if one artery is damaged or blocked.

Maintenance of Nasal Airflow and Mucosal Function

Support for Humidification and Warming of Air

The sphenopalatine artery provides blood to the mucosal surfaces of the nasal cavity and paranasal sinuses, which are responsible for humidifying and warming inhaled air. This process helps prevent dryness and irritation in the lower respiratory tract, improving the quality of air reaching the lungs.
The artery ensures that the mucosa remains well-perfused, allowing it to function effectively in air conditioning and filtration, which is crucial for maintaining respiratory health.

Nourishment for Mucus Production

The mucosal lining of the nasal cavity and sinuses produces mucus, which traps dust, allergens, and pathogens. The sphenopalatine artery’s blood supply supports the production of mucus, ensuring that the nasal passages remain clean and free from harmful particles.
This mucus also helps to prevent infections by trapping bacteria and viruses before they can enter the body, and by providing moisture to the air that is inhaled.

Support for Olfactory Function

Nourishment of the Olfactory Epithelium

The olfactory epithelium, located in the upper part of the nasal cavity, is responsible for the sense of smell.^[2] The sphenopalatine artery indirectly supports this sensory function by supplying blood to the surrounding mucosa, ensuring that the olfactory receptors remain well-oxygenated and functional.
This blood supply is vital for maintaining the health of the olfactory system, which depends on proper vascularization for detecting and processing smells.

Role in Thermoregulation and Immune Defense

Thermoregulation

The nasal mucosa, supplied by the sphenopalatine artery, plays a role in thermoregulation. As air passes through the nasal cavity, the blood vessels in the mucosa help regulate the temperature of the air, warming it before it reaches the lungs. This process is particularly important in cold environments, where the temperature of inhaled air needs to be adjusted to prevent lung irritation.
The artery’s blood flow helps ensure that the mucosa has the necessary resources to perform this function effectively.

Support for Immune Defense The blood supply provided by the sphenopalatine artery also supports the nasal mucosa’s role in the immune defense. The mucosa contains immune cells, such as macrophages and lymphocytes, that help protect against inhaled pathogens. The artery delivers oxygen and nutrients to these cells, ensuring that they function properly to defend the body from infections.

Clinical Significance

The sphenopalatine artery is clinically significant due to its role in supplying blood to the nasal cavity, paranasal sinuses, and surrounding structures.^[1] It is a major contributor to Kiesselbach’s plexus, an area prone to epistaxis (nosebleeds), particularly in cases of posterior nosebleeds, which can be difficult to manage due to their location and heavy bleeding. Severe epistaxis originating from the sphenopalatine artery often requires medical intervention, including cauterization or arterial ligation. The artery is also important in nasal and sinus surgeries, such as functional endoscopic sinus surgery (FESS) and procedures addressing chronic sinusitis. Damage to the sphenopalatine artery during surgery can lead to significant bleeding, requiring careful management by surgeons. Understanding the anatomy of this artery is essential for controlling nasal hemorrhages and for safe and effective sinus surgery.