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The pterygopalatine ganglion (ganglion of hay fever) is the largest parasympathetic peripheral ganglion.
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It serves as a relay station for the secretomotor fibres to the lacrimal gland and mucus glands of the nose, palate, pharynx, and paranasal sinuses.
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Topographically, it is related to the maxillary nerve, but functionally it is connected to the facial nerve through greater petrosal nerve
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Location: It is located deeply in the upper part of the pterygopalatine fossa, suspended from maxillary nerve by two short roots.
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Size: Head of a small pin.
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Relations
Behind: Pterygoid canal.
Medial: Sphenopalatine foramen.
In front: Perpendicular plate of palatine.
Above: Maxillary nerve.
- Roots
The roots of pterygopalatine ganglion are as follows:
A. Motor or parasympathetic root: It is derived from the
nerve of pterygoid canal. It carries preganglionic
parasympathetic fibres from superior salivatory nucleus
(located in the lower part of the pons). These fibres relay
in the ganglion. The postganglionic fibres arise from the
cells in the ganglion and supply secretomotor fibres to
the lacrimal gland, glands of the nose, palate,
nasopharynx, and paranasal sinuses.
B. Sympathetic root: It is derived from sympathetic plexus
around internal carotid artery via nerve of pterygoid
canal. It contains postganglionic fibres from superior
cervical sympathetic ganglion. These fibres pass through
the ganglion without relay and provide vasomotor
supply to the mucus membrane of the nose, palate,
pharynx, and paranasal air sinuses.
C. Sensory root: It is derived from maxillary nerve and
passes through the ganglion without interruption to be
distributed through the branches of the ganglion.
Branches of Distribution
The branches of the ganglion are actually the branches of
maxillary nerve, which passes through the ganglion without
relaying. While passing through the ganglion, they
incorporate the parasympathetic and sympathetic fibres of
the ganglion.
The ganglion provides the following four sets of branches:
A. Orbital.
B. Palatine.
C. Nasal.
D. Pharyngeal.
The orbital branches (2 or 3 in number) enter the orbit
through inferior orbital fissure and supply orbital
periosteum, ethmoidal air sinuses, and secretomotor fibres
to the lacrimal gland.
The palatine branches include greater and lesser palatine
nerves. The greater palatine nerve passes through greater
palatine canal and foramen to supply posteroinferior
quadrant of the lateral wall of the nose. The lesser palatine
nerves pass through lesser palatine canals and foramina to
supply secretomotor fibres to mucus membrane and glands
on the inferior surface of soft palate and hard palate.
The nasal branches pass through sphenopalatine foramen
to enter the nasal cavity. These are called posterior superior
nasal nerves. These are divided into two sets lateral and
medial. The nerves of lateral set supply lateral wall of the
nasal cavity while those of medial set supply roof and nasal
septum.
The longest branch of medial set is called nasopalatine/
sphenopalatine nerve. It runs anteroinferiorly in a groove
on the nasal septum and leaves the nasal cavity through the incisive foramen to enter the oral cavity where it supplies the anterior part of hard palate.
The pharyngeal branch passes through palatovaginal
canal and supply the nasopharynx.
CLINICAL ANATOMY: The allergic conditions, viz. hay-fever or cold, cause irritation of nerve of pterygoid canal/pterygopalatine ganglion, which causes congestion of glands of the nose and palate, and lacrimal gland. Consequently the individual suffers from running nose and eyes, for this reason the nerve of pterygoid canal is called nerve of hay fever and the pterygopalatine ganglion is termed ganglion of hay fever.