The canalis sinuosus is a small, often winding bony canal located within the upper jaw, known as the maxilla. This intricate structure plays a role in the complex network of nerves and blood vessels in the facial region. Its presence and variations are increasingly recognized with advanced imaging techniques, making its understanding important in various medical and dental fields.
Anatomy and Location
The canalis sinuosus originates from the infraorbital canal, behind the infraorbital foramen. From this origin, it curves downward and outward within the orbital floor of the maxilla, positioned to the side of the infraorbital canal. It then turns inward and forward, passing through the front wall of the maxillary sinus.
The canal then descends below the infraorbital foramen and proceeds towards the front margin of the nasal opening, anterior to the inferior nasal concha. It extends along the lower edge of the anterior nasal aperture, situated between the nasal cavity and the tooth sockets of the canine and incisor teeth. The canal ultimately terminates by opening near the nasal septum, just in front of the incisive canals, or at the nasal floor or anterior tooth region. The length of the canal can vary, potentially reaching up to 55 mm.
Function and Contents
The canalis sinuosus serves as a passageway for neurovascular structures, primarily housing the anterior superior alveolar nerve, artery, and vein. The anterior superior alveolar nerve is a branch of the infraorbital nerve. This nerve travels through the canalis sinuosus to provide sensation to the upper front teeth, including the incisors and canines.
Beyond the teeth, the anterior superior alveolar nerve also innervates the surrounding gum tissues, parts of the maxillary sinus lining, and the mucous membrane of the nasal cavity’s floor and anterior lateral wall, connecting with other nasal nerves. The anterior superior alveolar artery, a branch of the infraorbital artery, supplies blood to these same areas.
Clinical Importance
Understanding the canalis sinuosus is relevant in dental and maxillofacial procedures due to its contents and variable anatomy. During local anesthesia, especially infiltration techniques in the anterior maxilla, it can be encountered. Inadvertent injection or nerve damage can lead to inadequate anesthesia or temporary numbness or altered sensation in the lip or teeth.
Its presence also holds significance for dental implant placement in the anterior upper jaw. Surgeons carefully evaluate its location using advanced imaging like cone-beam computed tomography (CBCT) to avoid perforating the canal or injuring its neurovascular contents. Damage during implant surgery can result in complications such as bleeding, pain, or persistent numbness (paresthesia), sometimes necessitating implant removal.
Variations in the canalis sinuosus, including its course, diameter, and the presence of accessory canals, can influence treatment planning. Accessory canals are present in a significant percentage of individuals, ranging from approximately 35% to nearly 68%. Recognizing these anatomical differences through preoperative imaging helps clinicians plan surgical interventions to minimize risks and improve patient outcomes.