# Vascular Supply of the Face and Oral Cavity

## Overview

The face and oral cavity receive their blood supply primarily from branches of the external carotid artery. Rich anastomotic networks ensure robust perfusion but can complicate hemorrhage control during surgery and trauma. Dangerous anastomoses between the external and internal carotid systems exist and must be recognized to avoid catastrophic complications such as stroke or blindness. The venous drainage of the face is clinically significant because valveless veins create connections with the cavernous sinus, providing a pathway for infection spread to the intracranial compartment.

## External Carotid Artery

### Origin and Course

The external carotid artery arises from the common carotid artery bifurcation at the level of the upper border of the thyroid cartilage (C3-C4). At the bifurcation, it lies anteromedial to the internal carotid artery. It ascends deep to the posterior belly of the digastric and the stylohyoid muscles, then enters the substance of the parotid gland, where it divides into its terminal branches.

### Branches (Mnemonic: "Some Anatomists Like Freaking Out Poor Medical Students")

The ECA gives off eight named branches: the superior thyroid artery (anterior), ascending pharyngeal artery (medial), lingual artery (anterior), facial artery (anterior), occipital artery (posterior), posterior auricular artery (posterior), and two terminal branches -- the maxillary artery and the superficial temporal artery.

| Branch | Direction | Key Supply / Clinical Relevance |
|---|---|---|
| Superior thyroid artery | Anterior | Thyroid gland, larynx |
| Ascending pharyngeal artery | Medial | Pharynx, middle ear, meninges |
| Lingual artery | Anterior | Tongue, sublingual gland |
| Facial artery | Anterior | Face, lips, nose; palpable at mandibular border |
| Occipital artery | Posterior | Posterior scalp, sternocleidomastoid |
| Posterior auricular artery | Posterior | Ear, scalp posterior to ear |
| Maxillary artery | Terminal | Infratemporal fossa, pterygopalatine fossa, teeth |
| Superficial temporal artery | Terminal | Scalp; palpable over zygomatic arch |

## Facial Artery

### Course

The facial artery arises from the ECA above the lingual artery, though these two vessels may share a common trunk (the linguofacial trunk). It passes deep to the posterior belly of the digastric and stylohyoid, grooves the posterior surface of the submandibular gland, and crosses the inferior border of the mandible at the anterior border of the masseter, where it is palpable. From there, it follows a tortuous course across the face toward the medial canthus.

### Branches

The ascending palatine artery supplies the soft palate and tonsil. The tonsillar branch provides the main blood supply to the palatine tonsil. The submental artery runs along the inferior border of the mandible on the surface of the mylohyoid and is important in submental flap harvest. The inferior and superior labial arteries course within the lower and upper lips respectively; the superior labial artery gives off a septal branch to the nasal septum, which is a significant source of epistaxis. The lateral nasal artery supplies the ala of the nose. The angular artery is the terminal branch and anastomoses with the dorsal nasal artery, a branch of the ophthalmic artery.

### OMFS Relevance

Palpation of the facial artery at the mandibular border confirms ECA patency and serves as a landmark for surgical approaches. The superior labial artery is a common source of hemorrhage during lip lacerations or surgery. The angular artery-ophthalmic artery anastomosis represents an ECA-ICA connection that creates the risk of retrograde embolism during facial filler injections. The submental artery pedicled flap is a useful option for intraoral and lower face reconstruction.

## Maxillary Artery (Internal Maxillary Artery)

### Course and Parts

The maxillary artery is the larger terminal branch of the ECA. It arises within the parotid gland behind the neck of the mandibular condyle, and its course is divided into three parts defined by the relationship to the lateral pterygoid muscle.

#### First Part (Mandibular/Retromandibular)

The first part passes between the mandibular ramus and the sphenomandibular ligament. Its branches include the deep auricular artery (supplying the external acoustic meatus and tympanic membrane), the anterior tympanic artery (supplying the middle ear), the middle meningeal artery (which enters the skull through the foramen spinosum and is the classic source of epidural hematoma), and the inferior alveolar artery (which enters the mandibular foramen alongside the IAN, supplies the mandibular teeth, gives off the mylohyoid branch, and exits as the mental artery).

#### Second Part (Pterygoid)

The second part courses either superficial or deep to the lateral pterygoid muscle. Its branches include the deep temporal arteries, pterygoid branches, masseteric artery, and buccal artery.

#### Third Part (Pterygopalatine)

The third part enters the pterygopalatine fossa through the pterygomaxillary fissure and gives off several clinically important branches. The posterior superior alveolar artery descends along the maxillary tuberosity and supplies the maxillary molars and sinus membrane. The infraorbital artery traverses the infraorbital canal alongside the infraorbital nerve and supplies the maxillary anterior teeth (via its ASA branch), the floor of the orbit, the lower eyelid, and the upper lip. The greater (descending) palatine artery descends through the greater palatine canal, exits at the greater palatine foramen, supplies the hard palate, and anastomoses with the sphenopalatine artery via the incisive canal. The sphenopalatine artery is the terminal branch and enters the nasal cavity through the sphenopalatine foramen; it is the principal arterial supply of the nasal cavity and the primary source of posterior epistaxis at the Woodruff plexus. Additional branches include the artery of the pterygoid canal (Vidian artery) and the pharyngeal branch.

### OMFS Relevance

During Le Fort I osteotomy, the descending palatine artery is encountered during the lateral wall osteotomy and may be sacrificed; palatal viability is maintained because of the anastomotic supply from the ascending palatine and ascending pharyngeal arteries. Life-threatening bleeding during Le Fort I down-fracture can occur from the maxillary artery or its branches, with posterior maxillary (retromaxillary) hemorrhage being the most dangerous. During sinus lift surgery, the PSA artery may be encountered in the lateral antral wall, where an intraosseous anastomosis between the PSA and infraorbital arteries lies at a mean distance of 19 mm from the alveolar crest. Posterior epistaxis from the sphenopalatine artery is managed by nasal endoscopic ligation.

## Superficial Temporal Artery

### Course

The superficial temporal artery is a terminal branch of the ECA. It ascends anterior to the tragus of the ear, crosses the zygomatic arch, and divides into frontal and parietal branches. It is palpable over the zygomatic arch.

### OMFS Relevance

This artery serves as a landmark for preauricular and TMJ surgical approaches. Biopsy of the superficial temporal artery is performed when giant cell (temporal) arteritis is suspected. The frontal branch crosses over the zygomatic arch in a predictable location relevant to surgical planning.

## Dangerous Anastomoses (ECA-ICA Connections)

### Clinical Significance

Retrograde embolism through ECA-ICA anastomoses can cause stroke, blindness, or death. This risk is relevant during facial filler injections (especially in the nasal, glabellar, and nasolabial fold regions), embolization procedures, and uncontrolled hemorrhage with retrograde flow.

### Key Anastomotic Sites

The most clinically relevant anastomosis for filler complications is between the angular artery (a branch of the facial artery) and the dorsal nasal artery (a branch of the ophthalmic artery). Other important connections include the middle meningeal artery to the lacrimal or ophthalmic artery via the meningolacrimal anastomosis, the infraorbital artery to the ophthalmic artery through inferior orbital connections, and the sphenopalatine artery to the anterior ethmoidal artery within the nasal cavity.

| ECA Branch | ICA Branch | Anastomotic Site | Clinical Risk |
|---|---|---|---|
| Angular artery (facial) | Dorsal nasal artery (ophthalmic) | Medial canthus / nasal dorsum | Blindness from filler injection |
| Middle meningeal artery | Lacrimal / ophthalmic artery | Meningolacrimal anastomosis | Stroke during embolization |
| Infraorbital artery | Ophthalmic artery | Inferior orbit | Visual loss |
| Sphenopalatine artery | Anterior ethmoidal artery | Nasal cavity | Epistaxis management consideration |

## Venous Drainage

### Facial Vein

The facial vein accompanies the facial artery but takes a more direct, straighter course. It drains into the internal jugular vein via the common facial vein or into the external jugular vein. Critically, it is valveless, meaning it allows bidirectional flow.

### Pterygoid Venous Plexus

The pterygoid venous plexus is located around the lateral pterygoid and in the infratemporal fossa. It receives blood from the middle meningeal veins, deep temporal veins, and dental/alveolar veins. It communicates with the cavernous sinus via emissary veins that pass through the foramen ovale and foramen of Vesalius, providing a pathway for spread of infection from the face and oral cavity to the cavernous sinus.

### Retromandibular Vein

The retromandibular vein forms within the parotid gland from the junction of the maxillary and superficial temporal veins. It divides into an anterior division (which joins the facial vein) and a posterior division (which joins the posterior auricular vein to form the external jugular vein).

### Cavernous Sinus Thrombosis

Cavernous sinus thrombosis is a life-threatening complication of facial infections, particularly canine space infections and orbital cellulitis. Infection spreads via the valveless ophthalmic veins or the pterygoid plexus emissary veins. The condition presents with proptosis, ophthalmoplegia, chemosis, and fever, and it affects cranial nerves III, IV, V1, V2, and VI, all of which travel within or through the walls of the cavernous sinus.

## Hemorrhage Control in OMFS

### General Principles

Direct pressure is the first-line measure for accessible hemorrhage. The source should be identified as either arterial (pulsatile, bright red) or venous (continuous, dark). Control methods include electrocautery, hemostatic agents (Surgicel, Gelfoam, bone wax), and ligation.

### Specific Scenarios

#### Le Fort I Hemorrhage

Retromaxillary hemorrhage from the descending palatine artery, maxillary artery branches, or pterygoid plexus is managed with posterior nasal packing, direct pressure, vessel ligation, or electrocautery. Refractory cases may require external carotid artery ligation or angiographic embolization. Blood loss can be rapid and life-threatening, averaging 200-500 mL but reaching several liters in severe cases.

#### Third Molar Hemorrhage

Bleeding from the inferior alveolar artery within the mandibular canal is controlled with bone wax and Surgicel packing. Injury to the facial artery or buccal artery requires ligation or electrocautery.

#### Post-Extraction Hemorrhage

Local measures include pressure, Gelfoam or Surgicel placement in the socket, and suturing. Systemic causes such as coagulopathy, anticoagulant use, and liver disease should be considered in patients with disproportionate bleeding.

<image>Lateral view of the face showing the course and branching of the external carotid artery with emphasis on the facial artery (ascending from the submandibular region, crossing the mandible at the anterior border of the masseter, and terminating as the angular artery near the medial canthus) and the maxillary artery (passing behind the condylar neck and through the pterygopalatine fossa). Key branches including the inferior alveolar, descending palatine, sphenopalatine, and superficial temporal arteries are labeled.</image>

<image>Coronal section through the maxilla at the level of the first molar showing the intraosseous anastomosis between the posterior superior alveolar artery (entering from the lateral maxillary wall) and the infraorbital artery (within the infraorbital canal), relevant to lateral wall sinus augmentation. The Schneiderian membrane is shown lining the maxillary sinus floor, with the arterial anastomosis coursing within the bony lateral wall at a measured distance from the alveolar crest.</image>

<image>Sagittal view of the nasal cavity and hard palate demonstrating the arterial supply. The sphenopalatine artery enters posteriorly through the sphenopalatine foramen, the greater palatine artery descends through the palatine canal and courses anteriorly along the hard palate, and the two systems anastomose at the incisive foramen region (Kiesselbach plexus area). Branches of the superior labial artery contributing to the nasal septum blood supply are also shown.</image>

## Clinical Pearls

The facial artery is reliably palpated at the anterior border of the masseter along the inferior border of the mandible, making this the most consistent surface landmark for the vessel. During Le Fort I osteotomy, the descending palatine artery is typically sacrificed, but palatal blood supply is maintained through anastomoses from the ascending palatine and ascending pharyngeal arteries. The PSA-infraorbital artery intraosseous anastomosis in the lateral maxillary wall should be identified on CBCT before sinus augmentation, and the vessel may need to be cauterized if encountered. Life-threatening hemorrhage during Le Fort I down-fracture most commonly originates from the retromaxillary region, and packing combined with hypotensive anesthesia are first-line measures. Filler injections in the glabellar and nasal regions carry the highest risk of retrograde arterial embolism causing blindness, due to the angular-ophthalmic anastomosis. The valveless veins of the face create a direct conduit for infection spread to the cavernous sinus; the "danger triangle of the face" (from the bridge of the nose to the corners of the mouth) is where this risk is greatest. Underlying coagulopathy or anticoagulant use should always be considered in patients with disproportionate post-operative bleeding.

## References
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- Solar P, Geyerhofer U, Traxler H, et al. Blood supply to the maxillary sinus relevant to sinus floor elevation procedures. *Clin Oral Implants Res*. 1999;10(1):34-44.
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