Anatomy of the infraorbital vein: filling a crucial clinical gap

In the daily practice of oral and maxillofacial surgery, the infraorbital region constitutes a major surgical corridor, utilized during orbital floor reconstructions, orthognathic surgeries, or the treatment of zygomaticomaxillary complex fractures. However, while the infraorbital artery and nerve are perfectly documented, their venous counterpart — the infraorbital vein (IOV) — remains paradoxically misunderstood and often overlooked in standard anatomical texts. This gap exposes the practitioner to intraoperative complications such as troublesome bleeding, postoperative hematomas, or even, in rare cases, acute intraorbital hemorrhages.

The objective of this narrative review is to synthesize embryological and anatomical data to provide a precise clinical reference framework for surgeons. The authors of this review report that the IOV plays a pivotal role in the venous connections between the midface, the orbit, and the pterygoid venous plexus (PVP). The central hypothesis suggests that an in-depth knowledge of this network is essential not only to secure surgical access, but also to understand the spread pathways of odontogenic infections or septic thrombophlebitis toward deep cranial venous spaces.

Methodology

This narrative review synthesizes current knowledge on the embryology, anatomy, and variations of the infraorbital vein (IOV). The authors conducted a structured literature search, supplemented by a manual review of reference lists, to establish an anatomical framework oriented toward surgical practice.

To illustrate these data, the study relies on two complementary approaches:

• Clinical imaging: Analysis of axial computed tomography (CT) scans with contrast medium injection to identify infraorbital vessels in vivo.
• Anatomical dissection: Study of specimens from human cadavers. The protocol required the removal of the inferior wall of the infraorbital canal to expose the neurovascular bundle. The distinction between the nerve, artery, and vein was achieved by micro-dissection under a surgical microscope.

The morphological analysis focused on the structure of the venous network within the canal, identifying early branching characteristics relative to the other components of the bundle. All cadaveric procedures were performed in accordance with international consensus guidelines regarding the ethical use of human material in anatomical research.

Morphology and drainage dynamics

This narrative review highlights an anatomical lack of knowledge regarding the infraorbital vein (IOV) compared to its arterial and nerve counterparts. The major observation from microsurgical dissections shows that the IOV does not present as a single trunk, but adopts an early branching as soon as it enters the infraorbital canal. It divides into multiple small venous branches rather than a solitary vessel (Fig. 2).

Venous drainage follows a specific posterior path:

• Origin: Soft tissues of the midface and infraorbital region.
• Path: Passage through the infraorbital canal.
• Termination: Drainage into the pterygoid venous plexus (PVP) within the infratemporal fossa.

This configuration establishes a direct communication pathway between the midface, the orbit, and the deep venous spaces of the skull. The authors note that this anatomy is subject to high inter-individual variability, making its identification difficult during classic dissections without precise injection.

Embryological foundations

The study reports that the venous anatomy of the region derives from the primitive maxillary vein (PMV). During embryogenesis, the PMV provides the primary drainage for the maxillary bud and the ventral orbitonasal region. Its development is closely linked to the maxillary nerve (V2), which explains the neurovascular coupling observed in adults.

The VMP is then redistributed into two distinct components:

• A superficial component contributing to the formation of the facial vein.
• A deep component forming the maxillary vein and the PVP.

At the same time, the stapedial-external carotid arterial system gives rise to the infraorbital artery, which joins this complex to form the definitive neurovascular bundle.

Analysis and clinical perspectives

This narrative review highlights the often underestimated complexity of the infraorbital vein (IOV), a component frequently eclipsed by its arterial and nervous counterparts. The authors emphasize a major anatomical feature: contrary to classic diagrams, the IOV often appears upstream of the canal as multiple small branches rather than a single trunk. This plexiform configuration increases the exposure surface during midface surgical procedures, such as Le Fort I osteotomies or the reduction of zygomaticomaxillary complex fractures.

The connectivity of the IOV with the pterygoid venous plexus (PVP) and the inferior ophthalmic vein establishes a crucial deep drainage pathway. Clinically, this study demonstrates that the IOV is not only a potential source of intraoperative hemorrhage or postoperative hematoma, but also constitutes a vector for the spread of odontogenic infections. The risk of septic thrombophlebitis towards the deep venous spaces of the skull is an anatomical reality that the practitioner must integrate into their risk assessment.

The main limitation of this work lies in its nature as a narrative review, not following a formal systematic research protocol. However, by integrating embryological data related to the primitive maxillary vein, the study clarifies why this neurovascular bundle exhibits such inter-individual variability. For the surgeon, these findings require reconsidering the infraorbital area, often deemed safe, as a dynamic vascular crossroads where preserving the venous network is essential to prevent acute orbital complications.

In concrete terms, for the practitioner:

• Manage hemorrhagic risk: Anticipate diffuse bleeding during orbital floor or zygomatico-maxillary complex surgeries, as the often plexiform structure of the IOV makes its hemostasis more complex than that of a single vessel.
• Monitor septic spread: Identify the IOV as a retrograde drainage pathway to the pterygoid plexus, explaining the risk of ophthalmic complications or thrombophlebitis following infected dental procedures.
• Caution when accessing the foramen: Although the area is considered safe, the close proximity between the nerve (V2), the artery and these fragile venous ramifications requires meticulous dissection under visual control to avoid postoperative hematomas.

Technical lexicon of infra-orbital venous anatomy

Infraorbital vein (IOV): Venous component of the facial neurovascular bundle, characterized by early branching into multiple slender branches within the canal rather than a single trunk.

Pterygoid venous plexus (PVP): Collecting network located in the infratemporal fossa, serving as a deep outlet for mid-facial drainage and constituting a potential pathway for the spread of odontogenic infections.

Infraorbital canal: Critical surgical corridor housing the infraorbital vessels and nerve, frequently exposed during orbital floor reconstruction or orthognathic surgery.

Infraorbital groove: Bony groove preceding the canal, the manipulation of which during approaches to the zygomaticomaxillary complex can lead to troublesome bleeding or postoperative hematomas.

Inferior ophthalmic vein: Orbital venous structure of which some communication channels extend towards the infraorbital region, establishing an anatomical link between the orbit and the venous network of the face.

Infratemporal fossa: Deep anatomical space receiving venous drainage from the face via the infraorbital canal, central to the understanding of the spread of septic thrombophlebitis.

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