The Anatomy of the Maxillary Artery

The larger of the two terminal arteries arising from the external carotid artery in the upper-rear portion (called the “neck”) of the mandible (lower jaw bone), the maxillary artery is a primary source of blood for deep structures in the face and mouth. From its origin in the parotid gland—a source of saliva located in the space behind the jaw—this vessel passes frontwards and supplies deep structures within the face and head, including the mandible, teeth, chewing muscles, palate, nose, and cranial dura mater (the protective membrane surrounding the brain). 

Not only can problems arise due to blockages within this artery, but trauma here can also lead to extradural haematoma, a dangerous pooling of blood in the space between the cranium’s walls and the membranes that surround the brain. In addition, this artery can be involved in nose bleeds (epistaxis), and become affected by dental anesthesia.

Anatomy

A terminal branch of the external carotid artery, the maxillary artery at its origin is embedded in the parotid gland. Its course runs forward between the ramus of the mandible, an opening at the back of the jaw bone, and the sphenomandibular ligament, a flat, thin band connecting that bone to the skull.

From there it passes through the pterygopalatine fossa, an opening on each side of the skull allowing access to deep facial tissues and muscles. The artery terminates into the sphenopalatine artery near the nasal cavity.

Anatomical Variations

As with many arteries throughout the body, anatomical variations are not uncommon in the maxillary artery.

Most frequently, doctors have observed atypical branching patterns around the lateral pterygoid muscle, a muscle involved in chewing towards the back of the jaw. In some cases, there’s a common origin for the middle and accessory meningeal arteries, while in others the same trunk for the inferior alveolar and deep temporal arteries is seen.

In about 43% of cases, the maxillary artery runs deeper than the lateral pterygoid muscle rather than vice-versa. In other cases, the inferior alveolar artery emerges directly from the external carotid artery.

Finally, the origin of this artery can also vary, arising either at the origin of the maxillary artery, and in about 42% of cases, it emerges at or before the middle meningeal artery rather than after.

Function

The maxillary artery is primarily tasked with supplying blood to important structures in the mandible (lower jaw bone), maxilla (upper jaw bone), deep facial areas, the dura mater as well as the nasal cavity.

Mandibular

The branches of the first, mandibular part—that is, the one closest to the jaw—are:

• Deep auricular artery: This branch runs upwards into the inner ear to supply the tympanic membrane and external acoustic meatus, essential parts of the auditory system.
• Anterior tympanic artery: A major artery of the middle ear, this artery also supplies the tympanic membrane.
• Middle meningeal artery: Moving upwards to pass through the foramen spinosium, an opening at the base of the skull, this artery accesses and delivers blood to the dura mater there.  
• Inferior alveolar artery: This branch runs downwards and towards the front through the inferior alveolar nerve before reaching the mandibular nerve and parts of the mandible, supplying them with blood.  
• Accessory meningeal artery: Moving upwards through the middle fossa (opening) of the skull, this artery supplies the dura mater and the trigeminal ganglion region of the brain.

Pterygoid

The mandibular part is followed by the branches of the second, pterygoid part:

• Masseteric artery: A small artery that accompanies the lingual nerve in the tongue, this artery supplies essential muscles there.
• Pterygoid artery: This is a major supplier of blood to the pterygoid muscles, essential for chewing.
• Deep temporal artery: A branch that splits into two, the arteries here supply the temporalis and pericranium, which also are involved in chewing.
• Buccal artery: Running in a slanted course forward, this artery to reach the outer surface of the buccinator muscles—a major muscle underlying the cheek—before connecting with a number of other facial arteries. 

Pterygopalatine

Finally, quite a few branches arise from the pterygopalatine part, including:

• Sphenopalatine artery: This artery’s primary function is to supply the nasal cavity. As it passes through the sphenopalatine foramen (an opening in the skull leading to the nasal cavity), it breaks into further branches that supply the nose and the sensory apparatus there. 
• Descending palatine artery: This artery almost immediately splits into the greater and lesser palatine arteries, which supply the hard and soft palate: the front and back portions of the roof of the mouth.
• Infraorbital artery: This branch moves forward through the inferior orbital fissure, along the roof of the eye’s orbit, which is the socket that holds the eyeball. It then emerges from there to supply important facial nerves. This artery has two further branches associated with providing blood to the structures around the eyes and face: the anterior superior alveolar and middle superior alveolar arteries.
• Posterior superior alveolar artery: The primary source of blood for the upper row of teeth, it also serves the nerves that relay sensory information from them and the surrounding gum areas. 
• Pharyngeal artery: The primary task of the pharyngeal artery is to supply blood for the pharynx, a part of the throat behind the mouth and nasal cavity, above the esophagus. 
• Artery of the pterygoid canal: Running through the pterygoid canal—a passage through the middle of the skull at the sphenoid (rear) bone—this artery supplies the upper pharynx and the tympanic cavity within the ear.

Clinical Significance

Because of the maxillary artery’s role in supplying parts of the mouth, nose, and deep facial structures, it’s involved in a number of health conditions and treatments. These include:

• Dental anesthesia: Because of this artery’s role in supplying the upper set of teeth and gums and proximity there, care needs to be taken by dentists when injecting Novocain to manage pain during procedures.
• Nosebleed (epistaxis): The vessel’s role in supplying the nasal cavity means that it can be involved in nosebleeds. In severe cases, doctors may look to this one as the source of the problem.
• Internal carotid artery repair: In cases where the internal carotid artery—a major artery of the head and neck—is damaged, doctors have started looking into the role that the maxillary artery can play in normalizing blood circulation.
• Extradural haematoma: When the middle meningeal artery is damaged due to injury, as in a car accident or severe fall, cavities and tissues surrounding it—particularly the dura mater—can fill with blood due to rupture. This may increase pressure on the maxillary artery and requires swift attention.