Artery of Pterygoid Canal

The artery of the pterygoid canal, also known as the Vidian artery, is a small but significant branch of the maxillary artery or sometimes the internal carotid artery.^[8] This artery provides blood supply to structures in the pterygoid canal and surrounding regions. It travels through the pterygoid canal, which is a bony passage in the sphenoid bone that contains both the nerve and artery of the pterygoid canal.

Location

The artery of the pterygoid canal is located within the pterygoid canal (Vidian canal), which runs through the base of the sphenoid bone, connecting the middle cranial fossa with the pterygopalatine fossa. It accompanies the nerve of the pterygoid canal (Vidian nerve) along this canal. The artery terminates by supplying parts of the nasopharynx, auditory tube, and surrounding tissues.

Anatomy

Origin

The artery of the pterygoid canal is a branch that typically arises from either the third part of the maxillary artery or, less commonly, from the internal carotid artery.^[7] Its origin is within the pterygopalatine fossa, a crucial area where several important vascular and neural structures pass. Depending on its origin, the artery of the pterygoid canal may have slight variations in its course.

Course and Pathway

Pterygoid Canal (Vidian Canal)

The artery enters the pterygoid canal, also known as the Vidian canal, which is a bony passage located at the base of the sphenoid bone. The pterygoid canal runs horizontally and is positioned between the medial pterygoid plate and the foramen lacerum. The canal connects the pterygopalatine fossa with the middle cranial fossa, providing a pathway for both the artery and the accompanying nerve of the pterygoid canal (Vidian nerve), a mixed nerve formed by the union of the deep petrosal nerve and the greater petrosal nerve.

Relations with Surrounding Structures

The artery of the pterygoid canal runs alongside the nerve of the pterygoid canal, and both travel through the pterygoid canal together.^[6] It is in close relation to other branches of the maxillary artery and the pterygoid venous plexus. Additionally, it is adjacent to the sphenoid sinus and can be in proximity to the auditory tube (Eustachian tube) as it nears its distribution area.^[1]

Pterygopalatine Fossa

As the artery of the pterygoid canal originates from the maxillary artery in the pterygopalatine fossa, it is related to several important structures in this region, including:

• Maxillary nerve (CN V2)
• Pterygopalatine ganglion
• Other branches of the maxillary artery, such as the descending palatine artery and the sphenopalatine artery.

Branches and Distribution

After traveling through the pterygoid canal, the artery of the pterygoid canal gives off small branches that supply various surrounding structures. These include:

• Nasopharynx: The artery helps supply parts of the upper nasopharynx.
• Auditory (Eustachian) Tube: Small branches extend to the auditory tube, providing blood supply to this structure.^[5]
• Sphenoid Sinus and Surrounding Tissues: The artery provides minor blood supply to the nearby sphenoid sinus and adjacent structures.

Terminal Distribution

Upon exiting the pterygoid canal, the artery of the pterygoid canal terminates by supplying the nasopharynx, parts of the auditory tube, and adjacent areas. It may also anastomose with small branches from other arteries, including those from the internal carotid artery or the ascending pharyngeal artery, to form a network of blood supply in the region.

Anastomoses

The artery of the pterygoid canal may form small anastomoses with other nearby arterial structures. These anastomoses typically occur with branches of:

• Internal carotid artery
• Ascending pharyngeal artery
• Sphenopalatine artery

These connections provide collateral blood flow to the surrounding tissues of the nasopharynx, auditory tube, and adjacent sinuses.

Variations

The artery of the pterygoid canal may show anatomical variations, particularly in its origin. In some cases, it may arise from the internal carotid artery rather than the maxillary artery. Additionally, variations in the size, course, and branching pattern of this artery are also possible, depending on the individual anatomy and the exact route it takes through the pterygoid canal.

Function

The artery of the pterygoid canal, or Vidian artery, is responsible for supplying blood to specific structures in the nasopharyngeal region, middle ear, and adjacent areas. While it may be small compared to other arteries in the maxillary system, its role is vital in maintaining the blood supply to various key structures.^[4] Below is a detailed description of the artery's functions.

Blood Supply to the Nasopharynx

One of the primary functions of the artery of the pterygoid canal is to provide blood to the nasopharynx, the upper part of the throat located behind the nasal cavities.

• Nasopharyngeal Mucosa: The artery supplies the mucosal lining of the nasopharynx, ensuring that this area remains well-nourished and healthy. This blood supply supports the mucosa in its roles of filtering air, trapping particles, and aiding in immune responses.
• Nasopharyngeal Structures: The artery's branches provide nourishment to various structures within the nasopharynx, including small glands and lymphatic tissue, which are important for maintaining the health of the upper airway.

Blood Supply to the Auditory (Eustachian) Tube

The artery of the pterygoid canal plays a crucial role in supplying blood to the auditory tube, also known as the Eustachian tube. This tube connects the middle ear to the nasopharynx and helps maintain equal air pressure on both sides of the eardrum.

• Auditory Tube Mucosa: The blood supply from the artery ensures that the mucosa of the auditory tube remains functional, allowing it to open and close properly, which is essential for pressure regulation and preventing ear infections.
• Cartilage of the Auditory Tube: The artery also supplies the cartilage surrounding the auditory tube, which plays a mechanical role in its ability to open and close during swallowing or yawning. Proper vascularization ensures that this cartilage remains healthy and functional.

Blood Supply to the Sphenoid Sinus

The sphenoid sinus is one of the four paired paranasal sinuses located in the sphenoid bone. The artery of the pterygoid canal provides a minor but important blood supply to the mucosa lining the sphenoid sinus. Sphenoid Sinus Mucosa: The mucosa of the sphenoid sinus relies on this artery for oxygenation and nutrient delivery, which helps maintain sinus health. Adequate blood flow supports the mucosa’s role in moistening inhaled air and protecting the sinus cavity from pathogens and irritants.

Support for Middle Ear Structures

The artery of the pterygoid canal also contributes to the blood supply of the middle ear structures by supplying blood to parts of the auditory tube and indirectly through its anastomoses with nearby arteries. Blood Flow to the Tympanic Cavity: Through anastomotic connections, the artery of the pterygoid canal may play a role in the vascular supply of the middle ear structures, such as the tympanic cavity.^[3] Adequate blood flow helps maintain the function of the ossicles and the surrounding mucosa, crucial for hearing.

Anastomoses with Neighboring Arteries

The artery of the pterygoid canal forms small anastomoses with other nearby arteries, such as the internal carotid artery, ascending pharyngeal artery, and sphenopalatine artery. These anastomoses are important for:

• Collateral Circulation: The anastomoses ensure that in case of any reduction in blood flow from one artery, the surrounding tissues, including the nasopharynx, auditory tube, and sinuses, can still receive blood from alternate sources. This provides a safety mechanism for these delicate structures.
• Enhanced Blood Flow to the Pterygopalatine Region: Through these anastomoses, the artery of the pterygoid canal helps enhance the blood supply to the broader pterygopalatine region, contributing to the vascular network that supports the function of both the nasal and oral cavities.

Role in Supporting Immune Functions

By supplying blood to the lymphatic tissue in the nasopharynx, including the pharyngeal tonsils (also known as adenoids), the artery of the pterygoid canal indirectly supports the immune system. The pharyngeal tonsils are involved in trapping pathogens that enter the body through the nasal cavity, and a healthy blood supply ensures these tissues can function effectively in immune defense.

Role in Wound Healing and Tissue Repair

In case of injury or surgery involving the nasopharynx, auditory tube, or surrounding areas, the artery of the pterygoid canal plays an important role in providing blood flow for tissue healing and repair.^[2] Adequate vascular supply ensures that oxygen and nutrients reach the affected tissues, promoting faster recovery and minimizing complications.

Clinical Significance

The artery of the pterygoid canal is clinically significant due to its role in supplying blood to the nasopharynx, auditory tube, and parts of the sphenoid sinus. Injury to this artery can occur during surgical procedures in the pterygopalatine fossa, nasopharynx, or middle cranial fossa, such as in surgeries for sinus disease, tumors, or certain skull base procedures. Damage to the artery can lead to bleeding or hematoma formation, which may complicate surgical outcomes and healing. In certain cases, the artery may also be involved in vascular malformations or arteriovenous fistulas. Additionally, its anastomoses with the internal carotid artery and other surrounding vessels make it a point of interest in procedures dealing with vascular compromise in the region.