The maxillary vein is a short, deep vein located in the infratemporal fossa, which is a space behind the maxilla (upper jaw) and below the base of the skull. It is formed by the convergence of veins from the pterygoid venous plexus, a network of veins associated with the muscles of mastication and deep facial structures.
Location
The maxillary vein is situated in the infratemporal fossa, running posteriorly alongside the maxillary artery. It typically forms from the pterygoid plexus and travels backward to join the posterior division of the retromandibular vein, ultimately draining into the external jugular vein. The maxillary vein is closely associated with the deep structures of the face and the maxilla, making it an important part of the venous drainage system of the head.
Structure and Anatomy
Origin
The maxillary vein originates from the pterygoid venous plexus, which is a large network of interconnected veins located in the infratemporal fossa. The pterygoid plexus drains various structures in the deep face, including the muscles of mastication, the nasal cavity, the orbit, and the oral cavity. The maxillary vein forms from this plexus as it collects blood from the deep structures of the face.
Course and Pathway
Once formed, the maxillary vein follows a relatively short but important course. It runs posteriorly within the infratemporal fossa, accompanying the maxillary artery, which is one of the terminal branches of the external carotid artery. The maxillary vein runs posteriorly to the neck of the mandible and moves backward toward the parotid gland region.
As it travels, the maxillary vein lies deep within the face, passing close to the lateral pterygoid muscle and the ramus of the mandible. It typically runs parallel to the maxillary artery but remains within the venous compartment of the infratemporal fossa, just beneath the base of the skull.
Relations to Neighboring Structures
- Maxillary Artery: The maxillary vein runs parallel to the maxillary artery, although the two structures remain distinct. The artery supplies the deep face, while the vein drains it.
- Lateral Pterygoid Muscle: The maxillary vein is located near the lateral pterygoid muscle, one of the muscles of mastication, which is also closely associated with the pterygoid plexus.
- Mandibular Nerve (V3): The maxillary vein is located near the mandibular division of the trigeminal nerve (V3), which provides motor innervation to the muscles of mastication and sensory innervation to parts of the face.
- Parotid Gland: As the maxillary vein moves posteriorly, it approaches the parotid gland, an important salivary gland located near the mandibular angle. The retromandibular vein, which is formed in this region, passes through the parotid gland.
Tributaries
The maxillary vein receives blood from several smaller veins that drain the deep structures of the face and the areas supplied by the maxillary artery. These tributaries include:
- Veins from the Pterygoid Plexus: The primary source of blood for the maxillary vein is the pterygoid plexus, which drains the muscles of mastication, the nasal cavity, and the orbit.
- Veins from the Nasal Cavity: Some venous blood from the nasal cavity, particularly through the sphenopalatine veins, may also drain into the maxillary vein via the pterygoid plexus.
- Veins from the Teeth and Gums: Veins that drain the upper teeth and the surrounding gums also contribute to the pterygoid plexus and, ultimately, to the maxillary vein.
Termination
The maxillary vein travels posteriorly to join the retromandibular vein, a major venous channel that drains the lateral side of the face. More specifically, the maxillary vein joins the posterior division of the retromandibular vein, which then contributes to the formation of the external jugular vein. The external jugular vein eventually drains into the subclavian vein, continuing venous return to the heart.
Variations
The anatomy of the maxillary vein may vary between individuals, particularly in terms of its size and course. While the maxillary vein typically joins the posterior division of the retromandibular vein, there may be variations in the way it connects to the venous system. In some cases, the maxillary vein may have additional connections with other venous channels in the deep face or infratemporal region.
Communications with Other Venous Systems
The maxillary vein forms part of a larger network of venous connections that facilitate venous drainage from the deep face and head. These communications include:
- Pterygoid Plexus: The maxillary vein originates from the pterygoid venous plexus, which is a hub for venous drainage from the nasal cavity, teeth, muscles of mastication, and other deep structures of the face.
- Facial Vein: The maxillary vein indirectly communicates with the facial vein through the pterygoid plexus, allowing venous blood from the superficial and deep facial regions to be routed toward the external jugular vein.
- Cavernous Sinus: Through emissary veins that connect the pterygoid plexus with the cavernous sinus, the maxillary vein forms part of an important network of veins that communicate between the cranial cavity and the deep face.
Function
Venous Drainage of the Deep Face
The primary function of the maxillary vein is to facilitate the venous drainage of the deep structures of the face. It collects deoxygenated blood from key regions such as the muscles of mastication, the nasal cavity, the orbit, and the upper jaw (maxilla). By receiving blood from these areas, the maxillary vein helps maintain proper circulation and prevents the buildup of metabolic waste products in the deep facial tissues.
Drainage from the Pterygoid Venous Plexus
The maxillary vein is a crucial component of the venous outflow from the pterygoid venous plexus, a large network of veins in the infratemporal fossa. The plexus drains multiple regions, including:
- Muscles of mastication (masseter, temporalis, lateral and medial pterygoid muscles): These muscles, involved in chewing, produce metabolic waste that must be removed through venous drainage.
- Oral cavity: The maxillary vein collects venous blood from the structures in the oral cavity, including the upper teeth, gums, and hard palate.
- Nasal cavity: The plexus receives venous blood from the nasal cavity, especially through the sphenopalatine veins, which also contribute to the maxillary vein.
This drainage from the pterygoid venous plexus ensures that blood from the deep facial and cranial areas can be efficiently returned to the venous system, supporting normal metabolic processes.
Contribution to the External Jugular Venous System
The maxillary vein plays an important role in the overall venous return to the heart by contributing to the external jugular vein system. After collecting blood from the deep face, the maxillary vein joins the posterior division of the retromandibular vein, and together they form the external jugular vein. This vein carries blood down through the neck, eventually draining into the subclavian vein. Thus, the maxillary vein ensures the proper return of venous blood from the deep structures of the face to the central venous circulation, where it can be oxygenated by the lungs.
Regulation of Venous Pressure
The maxillary vein also helps in the regulation of venous pressure within the deep face, particularly during movements of the jaw, such as chewing or talking. These actions create pressure fluctuations in the muscles of mastication, which can affect venous blood flow. The maxillary vein, along with the pterygoid venous plexus, acts as a buffer, accommodating these changes in pressure and ensuring continuous venous drainage from the deep facial structures. This dynamic regulation of pressure prevents congestion in the face, allowing proper venous return even during periods of increased muscular activity.
Collateral Circulation and Venous Redundancy
The maxillary vein is part of a larger network of venous connections that facilitate collateral circulation in the face and head. Through its communications with the pterygoid venous plexus, facial vein, and cavernous sinus, the maxillary vein provides alternative pathways for venous drainage. This collateral circulation is particularly important in situations where one of the primary venous routes becomes blocked or obstructed. If such an obstruction occurs, the venous blood can be rerouted through the maxillary vein and its associated plexus, ensuring that venous return from the deep face is not compromised.
Connection to the Cavernous Sinus
The maxillary vein, through the pterygoid plexus, communicates with the cavernous sinus, a large venous sinus located in the cranial cavity. This connection is important because it allows venous blood to flow between the deep facial structures and the intracranial venous system. In particular, the emissary veins provide a route for venous blood to travel between the pterygoid plexus and the cavernous sinus. This pathway is crucial for maintaining a balance in venous drainage between the face and the brain, ensuring that the venous pressure remains stable across these connected regions.
Venous Drainage from the Upper Jaw (Maxilla) and Teeth
The maxillary vein also plays an important role in draining venous blood from the upper jaw (maxilla) and the upper teeth. The maxillary vein collects blood from veins that drain the gums, teeth, and surrounding soft tissues in the upper jaw. This ensures the removal of deoxygenated blood and waste products from these areas, contributing to the health of the maxilla and maintaining proper function in the oral cavity.
Temperature Regulation in the Deep Face
Although a minor function, the maxillary vein, like other superficial and deep veins in the head, contributes to thermoregulation by allowing heat exchange between the blood and the surrounding tissues. As blood flows through the maxillary vein, it can dissipate heat generated by the muscles of mastication and other structures during periods of physical activity, such as chewing. This cooling mechanism helps regulate the temperature of the deep facial tissues and prevents overheating.
Clinical Significance
The maxillary vein plays a vital role in venous drainage from the deep structures of the face, including the muscles of mastication, nasal cavity, and oral cavity. Its close association with the pterygoid venous plexus makes it significant in both surgical and dental contexts, particularly in procedures involving the maxilla, mandible, or upper teeth. Damage to the maxillary vein during dental surgeries, such as tooth extractions, or maxillofacial surgeries can result in significant bleeding, as the vein is part of a highly anastomosed venous network.
The maxillary vein also has connections to the cavernous sinus, which can provide a potential route for infections from the face to spread intracranially, leading to conditions like cavernous sinus thrombosis. Additionally, its role in collateral circulation ensures that it can compensate for obstructions in other venous pathways, highlighting its importance in maintaining proper venous return from the deep facial structures.
