The sphenopalatine artery enters the back of the nasal cavity, the inside of the nose, providing blood supply to the inner and outer walls of the nasal cavity and to the adjacent sinuses. It is clinically important since it is a frequent cause of nosebleeds.

Anatomy

The nasal cavity is a space inside the nose and face that conditions air taken in by the nose, passing it on to the rest of the respiratory system. In the back, the nasal cavity communicates with the oral cavity (the mouth) via a space called the nasopharynx.

The inside of the nose is encased in bones and cartilage, and is divided in two by a vertical wall called the nasal septum, which is also made up of bones and cartilage. Along the posterior, lateral wall of the nasal cavity is the sphenopalatine foramen, a tiny hole through which the sphenopalatine artery enters the nasal cavity.

Location

The sphenopalatine artery is the last branch of the maxillary artery, which is a branch of the external carotid artery, a major artery supplying the head and neck. The maxillary artery runs through the pterygopalatine fossa and passes through the sphenopalatine foramen. At this point, it becomes the sphenopalatine artery.

Structure

The sphenopalatine artery gives off several branches. It gives off a pharyngeal branch, then divides in the nasal cavity into the lateral nasal artery and septal nasal artery. The lateral nasal artery, as its name implies, supplies the lateral (outer) wall of the nasal cavity and the maxillary sinuses, which are located lateral to the nasal cavity.

Anatomical Variations

As with many arteries, anatomy can vary slightly from person to person. For example, the sphenopalatine artery usually divides into two branches after entering the nasal cavity. However, in some patients, the artery may divide before entering the cavity. In others, the sphenopalatine artery may divide into three or more branches. Surgeons planning nasal surgeries should be aware of potential variations in anatomy.

Function

The septal nasal artery supplies blood to the nasal septum, along the medial (inner) wall of the nasal cavity, and to the roof of the nasal cavity. Branches of the artery run forward along the septum and anastomose (interconnect) with branches of the anterior ethmoid artery, greater palatine artery, and superior labial artery, forming a network of vessels called Kiesselbach’s plexus.

Clinical Significance

The sphenopalatine artery and its branches are an important cause of nosebleeds (epistaxis). Nosebleeds can be classified as anterior or posterior, depending on the vessels that supply the injured mucosa. Anterior nosebleeds, the most common type, typically arise from Kiesselbach’s plexus. Posterior nosebleeds are less common, and typically arise from branches of the sphenopalatine artery, though branches of the internal carotid artery may also be involved.

Nosebleeds are usually the result of trauma or irritation to the nasal mucosa, the lining of the nasal cavity. Potential causes of mucosal injury include:

  • Nose picking
  • Foreign bodies
  • Dry air
  • Allergic rhinitis (hay fever)
  • Facial trauma
  • Chronic irritation (such as with intranasal drug use)

The sphenopalatine artery can also be injured by surgery involving the nasal cavity, including:

  • Sinus surgeryPituitary surgeryOther maxillofacial surgeries

Inadvertent injury to the artery may cause abnormal ballooning of the vessel, or pseudoaneurysm, which leads to severe bleeding.

Treatment

Although both anterior and posterior nosebleeds may cause rapid bleeding, minor bleeds are more likely to be anterior. The treatment differs depending on the source of the bleeding. Anterior nosebleeds may stop on their own, or respond to conservative measures such as pinching the nose.

Anterior Nosebleeds

More significant anterior nosebleeds may require more extensive treatment, such as:

  • Nasal packing (packing gauze high up in the nose to absorb blood)Cautery (a chemical or electrical device is applied to the mucous membranes in the nose to stop bleeding)Placement of a balloon catheterUse of a thrombogenic product (a substance that promotes the clotting of blood)

Posterior Nosebleeds

Posterior nosebleeds may result in significant bleeding. Though nasal packing or balloon catheters may be used as an initial measure, most patients with a posterior bleed need to be referred to an emergency department where an otolaryngologist is available. Stopping the bleeding may eventually require a surgical procedure, such as ligation or embolization of the responsible artery.

Pseudoaneurysm of the sphenopalatine artery caused by surgery may present with severe bleeding. As with posterior nosebleeds, control of bleeding may require ligation or embolization of the feeding artery.