The Anatomy of the Pterygopalatine Ganglion

The pterygopalatine ganglion is a parasympathetic nerve ganglion and one of four paired parasympathetic ganglia in your head. It sends out connections to the tear glands and mucous membranes of your mouth, throat, and nasal passages. Nerves from this ganglion are associated with a group of cluster headache disorders called trigeminal autonomic cephalalgias (TACs).

The pterygopalatine ganglion goes by several other names, including Meckel’s ganglion, nasal ganglion, and sphenopalatine ganglion (SPG).

Anatomy

The parasympathetic and sympathetic nervous systems together make up the autonomic nervous system, which controls all of the automatic functions of your body, such as heart rate, breathing, body temperature, glandular activity, and hormonal balance.

Most of the time, parasympathetic activity dominates. It deals with everything that happens while you’re in a typical, relaxed state. This state is often referred to as “rest and digest.” When you find yourself in a frightening or dangerous situation, the sympathetic nervous system takes over, speeding up your heart rate, dumping adrenaline into your bloodstream, and allowing the fight-or-flight mechanisms to take over.

Most nerve structures, including ganglia, exist in symmetrical pairs (one on each side of your body). Even so, they’re usually referred to in the singular. 

Structure

The four paired parasympathetic ganglia in your head are the:

• Submandibular ganglion in your lower jaw
• Otic ganglion behind your ear
• Ciliary ganglion behind your eye
• Pterygopalatine ganglion behind your cheekbone

The pterygopalatine ganglion is the largest of these structures. It contains parasympathetic nerve fibers, as well as sympathetic and sensory fibers.

Location

The pterygopalatine ganglion sits in the recess area of the skull called the pterygopalatine fossa, near an opening in the skull called the sphenopalatine foramen, and just below the maxillary nerve where it crosses the fossa.

The ganglion itself is enclosed in a capsule of reddish-gray connective tissue. Its shape has been described as triangular, conical, heart shaped, or pear shaped.

Most of the nerve fibers in the ganglion come from the greater petrosal branch of the facial nerve (the seventh cranial nerve or CN VII). When the nerves leave the ganglion, they travel with the pterygopalatine branches of the maxillary nerve, which is part of the trigeminal nerve (fifth cranial nerve or CNV).

After the nerve fibers pass through the ganglion, they leave to form multiple branches:

• Orbital branches
• Nasopalatine nerve
• Greater palatine nerve
• Lesser palatine nerve
• Nasal branches (medial, lateral posterior superior, and posterior inferior)
• Pharyngeal branch of the maxillary nerve

Anatomical Variations

While a “standard” exists for most anatomical structures, some variation is natural. Possible variations of nerves and nerve structures are important for doctors to know, especially for surgical procedures or administration of local anesthesia.

Researchers have defined four different formations of the pterygopalatine ganglion depending on whether it’s a single unit or has a partition, and where the Vidian nerve enters it. The Vidian nerve is a combination of the greater petrosal and deep petrosal nerves, and it arrives at the pterygopalatine ganglion by way of the pterygoid canal.

The variations are as follows:

• Type A: Ganglion is partitioned and the Vidian nerve enters the upper partition.
• Type B: Ganglion is a single structure and the Vidian nerve enters the upper portion. It’s the most common of all types.
• Type C: Ganglion is a single structure and the Vidian nerve enters the lower end.
• Type D: Ganglion is partitioned and the Vidian nerve enters the lower partition.

Function

Each branch that emerges from the pterygopalatine ganglion travels toward the face and innervates (supplies nerve function to) different structures. Some of these functions are sensory (detecting pressure, temperature, and other information from the senses), while others have a specialized motor (movement) function called secretomotor, which is what allows glands to secrete fluids.

Orbital Branch

Also called the zygomatic nerve, the orbital branch sends a communicating branch of parasympathetic fibers to the lacrimal nerve, which allows the lacrimal nerve to provide secretomotor function to the lacrimal (tear) glands.

Nasopalatine Nerve 

The nasopalatine nerve runs along the top of the nasal cavity, down the nasal septum, then to the roof of the mouth, to the front of the nasal cavity, and down to the hard palate and gums. It provides sensory innervation to the septum and front portion of the palate, secretomotor function to mucosal glands, and specialized sensory fibers for taste.

Greater Palatine Nerve 

The greater palatine nerve leaves the pterygopalatine ganglion with sensory and parasympathetic fibers. It descends through the greater palatine canal to reach the hard palate. From there, it passes through a groove in the palate to supply sensory function to the gums and secretomotor function to the mucous membrane and glands of the hard palate.

Lesser Palatine Nerve 

Traveling along the same initial course as the greater palatine nerve, this nerve supplies sensory function to the:

• Soft palate
• Tonsils
• Uvula

Nasal Branches

The greater and lesser palatine nerves, as they travel through the pterygopalatine canal, give off nasal branches that travel through openings in the palatine bone to provide sensory innervation to the nasal cavity.

Pharyngeal Branch of the Maxillary Nerve

This branch leaves the ganglion, passing through the pharyngeal canal to reach the nasopharynx (cavity behind the nose and mouth) to provide sensory innervation to the mucous membrane of the upper portion of the nasopharynx.

Associated Conditions

The pterygopalatine ganglion is believed to play an important role in numerous pain syndromes and other conditions, including:

• Headaches, especially a type of cluster headache called trigeminal autonomic cephalalgias (TACs), which can cause watering eyes
• Trigeminal neuralgia and sphenopalatine neuralgia (nerve pain)
• Atypical facial pain
• Vasomotor rhinitis (congestion caused by dilated blood vessels in the nose)
• Eye disorders
• Herpes infection

Additionally, pterygopalatine ganglion injury is suspected in subarachnoid hemorrhage (bleeding from a damaged artery on the brain’s surface), which may cause the symptom of dry eye.

Rehabilitation

Studies have shown that the conditions associated with the pterygopalatine ganglion can be effectively treated with a sphenopalatine ganglion blockade (SPGB). The same procedure is used for nasal and dental surgeries, as well as for treating some cancer pain.

Other treatments for cluster headaches related to this ganglion include:

• Pulsed radiofrequency ablation
• Neurostimulation of the ganglion

Summary

The pterygopalatine ganglion is a cluster of nerves behind your cheekbone that is important to the normal functioning of several parts of your face, including your nose, mouth, and throat. It plays a role in several pain conditions, such as cluster headaches.