Cranial sutures are fibrous joints found only in the skull, functioning as junctions between the bones of the cranium. Deep within the facial skeleton lies the pterygomaxillary suture, a landmark situated in a complex region of the head relevant to several medical and dental fields.
Anatomy of the Pterygomaxillary Suture
The pterygomaxillary suture articulates the posterior surface of the maxilla, or upper jaw bone, with the pterygoid process of the sphenoid bone. This junction is located inferiorly to the pterygomaxillary fissure, a gap connecting two important spaces in the skull. The suture represents the direct contact zone between the maxillary tuberosity and the lateral plate of the pterygoid process.
The suture’s morphology is described by its height, thickness, and angulation. The average height is around 22 mm and its width is approximately 7 mm, with no significant differences between the right and left sides of the skull.
Nearby anatomical structures include the maxillary sinus in front, the pterygoid plexus of veins behind, and the greater palatine foramen medially. Superiorly, the internal maxillary artery enters the pterygomaxillary fissure. This dense environment makes surgical access challenging.
Role in Craniofacial Development
The pterygomaxillary suture plays a part in the growth of the midface. This suture is an active site of bone growth, contributing to the downward and forward displacement of the maxilla during childhood and adolescence. This process helps create space for the eruption of permanent teeth and shapes the overall facial profile. The growth at this suture helps ensure that the upper and lower jaws align properly.
The suture’s activity gradually decreases as an individual matures. The process of ossification, or fusion of the two bones, begins during late adolescence and continues into early adulthood. Once the suture is fully fused, it is no longer a site of active growth. The timing of this fusion is a consideration in orthodontic treatments that aim to modify jaw growth.
While some studies suggest a decrease in the suture’s thickness with age, its basic structure remains relatively stable in adulthood after ossification is complete.
Clinical Significance in Dentistry and Medicine
In orthodontics, treatments such as rapid maxillary expansion, which aims to widen a narrow upper jaw, encounter resistance from this suture. Understanding the orientation and morphology of the suture can help clinicians apply forces more effectively to achieve the desired skeletal changes. The suture’s location and strength are factors that influence the success of such procedures.
In maxillofacial surgery, the suture is a landmark for procedures like the Le Fort I osteotomy. This surgery involves cutting the maxilla to reposition it for the correction of dentofacial deformities. A challenging step is the separation of the maxilla from the pterygoid plates at the suture. Precise disjunction is necessary to avoid complications like unfavorable fractures or injury to nearby blood vessels.
Radiographic imaging is used to visualize the suture for diagnosis and treatment planning. Cone-beam computed tomography (CBCT) scans provide detailed three-dimensional views of the suture’s thickness, height, and angulation. This information helps surgeons plan the precise angle of approach for osteotomies, minimizing surgical risks.
Involvement in Facial Trauma
The pterygomaxillary suture is frequently involved in significant midface trauma and is a characteristic feature of Le Fort I fractures. These fractures involve a horizontal detachment of the maxilla from the rest of the facial skeleton. The fracture line extends through the floor of the nose, the maxillary sinuses, and posteriorly, through the pterygomaxillary junction.
Disjunction at this suture mobilizes the entire lower portion of the midface, including the upper teeth, palate, and lower part of the maxillary sinuses. The diagnosis of such an injury relies on identifying this specific disruption on clinical examination and radiographic imaging. The complexity of the anatomy means that fractures can sometimes extend in unpredictable ways.
The treatment of Le Fort I fractures requires surgical intervention to realign and stabilize the fractured segments. Surgeons must understand the anatomy of the pterygomaxillary region to achieve a stable repair. The presence of a fracture through this junction can increase the risk of complications during surgery, given the proximity of major blood vessels and nerves.