Infra-orbital artery

The infra-orbital artery is a branch of the third part of the maxillary artery, which arises in the pterygopalatine fossa.^[7] This artery supplies blood to the lower eyelid, upper cheek, lateral nose, and parts of the upper lip.

Location

The infra-orbital artery travels through the infra-orbital fissure into the infra-orbital canal, where it runs along with the infra-orbital nerve. It emerges from the infra-orbital foramen, located on the anterior surface of the maxilla, just below the orbit. Once it exits through the infra-orbital foramen, the artery provides branches that supply the skin and muscles of the face in the region around the lower eyelid, upper lip, and cheek.

Anatomy

Origin

The infra-orbital artery originates from the third part of the maxillary artery, which is a terminal branch of the external carotid artery. The maxillary artery arises in the infratemporal fossa and travels through the pterygopalatine fossa, where it gives rise to several important branches, including the infra-orbital artery.

Course and Pathway

Pterygopalatine Fossa

After originating from the maxillary artery, the infra-orbital artery passes through the pterygopalatine fossa, a space between the maxilla, sphenoid, and palatine bones. In this fossa, it runs in close association with the infra-orbital nerve and other branches of the maxillary artery.

Infra-orbital Fissure

From the pterygopalatine fossa, the infra-orbital artery enters the inferior orbital fissure, a narrow opening located between the greater wing of the sphenoid bone and the maxilla. This fissure connects the pterygopalatine fossa to the orbit, allowing the infra-orbital artery to enter the orbit.

Infra-orbital Canal

Once inside the orbit, the infra-orbital artery enters the infra-orbital canal. The infra-orbital canal is located on the floor of the orbit within the maxilla, where the artery runs alongside the infra-orbital nerve.^[5] This canal carries both the artery and the nerve anteriorly toward the face.

Infra-orbital Foramen

The infra-orbital artery exits the infra-orbital canal through the infra-orbital foramen, a small opening located on the anterior surface of the maxilla, just below the margin of the orbit. The infra-orbital foramen is an important landmark for both surgical procedures and anesthesia.

Branching

During its course through the infra-orbital canal, the infra-orbital artery gives off several important branches:

Anterior Superior Alveolar Artery

The anterior superior alveolar artery is a notable branch that arises from the infra-orbital artery while it is still within the infra-orbital canal.^[3] This artery descends to supply the anterior maxillary teeth, including the canines and incisors, and the surrounding structures.

Facial Branches

After emerging from the infra-orbital foramen, the infra-orbital artery divides into several facial branches that supply the skin, muscles, and soft tissues of the lower eyelid, lateral side of the nose, upper cheek, and upper lip.

Anastomoses

The infra-orbital artery forms several important anastomoses with neighboring arteries, including:

• Facial artery: After emerging from the infra-orbital foramen, the infra-orbital artery anastomoses with branches of the facial artery, which supplies the lower parts of the face, including the upper lip and surrounding regions.
• Ophthalmic artery: Within the orbit, the infra-orbital artery anastomoses with the branches of the ophthalmic artery, ensuring that the orbit receives adequate blood supply.
• Posterior superior alveolar artery: The anterior superior alveolar branch of the infra-orbital artery anastomoses with the posterior superior alveolar artery, creating a vascular network that supplies the maxillary teeth and maxillary sinus.

Distribution

The infra-orbital artery provides blood supply to several important facial and oral structures. These include:

• Lower eyelid: After exiting the infra-orbital foramen, the artery supplies the skin and underlying tissues of the lower eyelid.
• Cheek and lateral nose: The artery sends branches to the skin, muscles, and soft tissues of the lateral nose and cheek, supporting the blood supply to these facial areas.
• Upper lip: Branches from the infra-orbital artery provide blood to the upper lip, ensuring nourishment of the skin, mucosa, and muscles in this region.

Relations

The infra-orbital artery runs in close proximity to the infra-orbital nerve, which is a branch of the maxillary nerve (CN V2). Both the artery and the nerve travel together through the infra-orbital fissure, infra-orbital canal, and infra-orbital foramen.^[1] This close relationship is clinically significant in procedures involving the orbit and midface, as both structures are often encountered together.

Variations

Anatomical variations of the infra-orbital artery are not common, but may occur in its size, course, or branching pattern. Some individuals may have a slightly larger or smaller artery depending on individual anatomy, or variations in its anastomoses with neighboring arteries may be observed. These variations can be important in surgical procedures or during anesthesia administration.

Function

The infra-orbital artery plays a crucial role in supplying blood to various facial and oral structures. Its main function is to provide oxygenated blood to areas around the lower eyelid, cheek, upper lip, lateral nose, and anterior maxillary teeth. Below is a detailed description of the functions of this artery.

Blood Supply to the Lower Eyelid

The infra-orbital artery supplies blood to the lower eyelid, including the skin, subcutaneous tissue, and underlying muscles.

• Skin and Subcutaneous Tissue: The artery nourishes the skin and connective tissues of the lower eyelid, ensuring these areas remain healthy and maintain their structural integrity.
• Orbicularis Oculi Muscle: The orbicularis oculi muscle, which is responsible for eyelid movements such as blinking, is also supplied by the infra-orbital artery.^[8] Adequate blood flow to this muscle supports its function and prevents fatigue or damage to the delicate tissues of the lower eyelid.

Blood Supply to the Upper Lip

The infra-orbital artery plays a significant role in supplying the upper lip, ensuring that the tissues in this area receive sufficient nutrients and oxygen.

• Skin and Musculature: The artery provides blood to the muscles of facial expression located in the upper lip, particularly the orbicularis oris muscle, which controls movements of the lips. This helps maintain muscle function and skin health in the region.
• Labial Mucosa: It also supplies blood to the mucosal surface of the upper lip, maintaining the health of the inner lining and contributing to wound healing if necessary.

Blood Supply to the Cheek and Lateral Nose

The cheek and lateral nose receive branches from the infra-orbital artery, which nourish the skin, underlying muscles, and connective tissues.

• Facial Muscles: The infra-orbital artery supplies the muscles responsible for facial expressions, including the levator labii superioris and levator anguli oris, which elevate the upper lip and corner of the mouth. These muscles rely on a steady blood supply to function properly.
• Nasal Region: The lateral part of the nose is also supplied by branches of the infra-orbital artery. The artery helps sustain the tissues around the nose, which are important for facial aesthetics and nasal functions such as airflow regulation.

Blood Supply to the Anterior Maxillary Teeth

One of the most important functions of the infra-orbital artery is to supply the anterior maxillary teeth, including the canines and incisors. This is achieved through its branch, the anterior superior alveolar artery.

• Dental Pulp: The anterior superior alveolar artery provides blood to the dental pulp of the anterior teeth. This ensures the pulp tissues remain healthy and vital, supporting tooth survival and function.
• Periodontal Ligaments: The artery also supplies the periodontal ligaments, which anchor the teeth to the surrounding alveolar bone. These ligaments require a steady blood supply to maintain their strength and support for the teeth.
• Alveolar Bone: The alveolar bone surrounding the teeth is nourished by the artery. This helps maintain bone health and density, preventing conditions like bone resorption that could lead to tooth mobility or loss.^[6]

Contribution to the Maxillary Sinus

The infra-orbital artery also contributes to the blood supply of the maxillary sinus. Small branches from the artery extend to the mucosa of the maxillary sinus, ensuring that this tissue receives adequate blood flow.

• Maxillary Sinus Mucosa: The mucosal lining of the maxillary sinus requires a rich blood supply for the production of mucus and for its role in protecting the respiratory system. The artery ensures the sinus remains functional and healthy.

Support for Facial Aesthetic and Sensory Functions

The infra-orbital artery indirectly supports the sensory and aesthetic functions of the midface by providing blood to critical tissues.

• Facial Aesthetics: By supplying the skin, muscles, and other soft tissues of the lower eyelid, cheek, and upper lip, the artery plays a role in maintaining facial aesthetics. A healthy blood supply ensures proper skin tone, muscle function, and tissue resilience, all of which are important for facial expressions and appearance.
• Nerve Support: Although the infra-orbital nerve is primarily responsible for sensory innervation in the area, the artery's blood supply ensures the nerve remains healthy and functional, supporting the sensory functions of the lower eyelid, cheek, lateral nose, and upper lip.

Anastomosis and Collateral Circulation

The infra-orbital artery forms anastomoses with other facial arteries, such as the facial artery and ophthalmic artery, creating a collateral blood supply to the face.

• Collateral Circulation: These anastomoses ensure that if one arterial route is compromised, blood flow can still reach the affected area through another route.^[4] This collateral circulation is particularly important during facial trauma or surgeries, as it helps prevent ischemia (reduced blood flow) in the region.
• Vascular Network for the Maxilla: The artery's anastomosis with the posterior superior alveolar artery helps create a continuous blood supply to the upper jaw, ensuring that the entire maxilla, including the teeth, receives adequate blood.

Role in Wound Healing and Tissue Repair

In addition to its function in normal physiology, the infra-orbital artery is important for wound healing and tissue repair in the face.

• Post-Surgical Healing: Following facial surgeries or dental procedures, such as tooth extractions, implants, or sinus surgeries, the blood flow provided by the infra-orbital artery supports tissue regeneration and recovery.
• Tissue Repair: The artery's supply of oxygen and nutrients helps in the repair of damaged skin, mucosa, and muscles after injuries, ensuring that the face heals properly and reducing the risk of complications.

Clinical Significance

The infra-orbital artery is clinically significant due to its involvement in both dental and facial surgical procedures.^[2] Its proximity to the infra-orbital nerve makes it an important structure to consider during facial trauma repair, cosmetic surgeries (such as rhinoplasty and facial reconstructions), and dental procedures like maxillary sinus surgeries or tooth extractions. Damage to the infra-orbital artery can lead to excessive bleeding, hematoma formation, or compromised blood supply to the tissues of the lower eyelid, cheek, lateral nose, and upper lip. Knowledge of its course is essential in administering infra-orbital nerve blocks for anesthesia in dental procedures, as unintentional injury can cause complications, including facial numbness or swelling. Proper understanding of its anatomical relations helps minimize the risk of vascular injury during surgeries and ensures better post-operative outcomes.