Meckel's or the spheno-palatine ganglion is found in the spheno-maxillary (pterygo-palatine) fossa. It lies immediately below the superior maxillary nerve and near to the spheno-palatine foramen.
The sensory roots of the spheno-palatine ganglion are derived from the superior maxillary, while the motor and sympathetic fibres are conveyed by the Vidian (nerve of the pterygoid canal). The Vidian is formed by the junction of the greater superficial petrosal branch of the facial nerve with the deep petrosal branch of the carotid sympathetic plexus.
There are seven branches arranged in four groups, namely :-
(a) Orbital, a minute twig to the orbital periostum.
(b) Pharyngeal supplies the mucous membrane of the roof of the pharynx.
(c) Palatine, anterior, middle, and posterior, which descend through separate bony canals to ramify in the mucous membrane of the hard and soft palate. The anterior palatine gives off an inferior nasal branch to the mucous membrane of the nose.
(d) Nasal enter the nose via the spheno-palatine foramen. They are two in number, a superior nasal, and a naso-palatine. The latter crosses the root of the nose and passes obliquely downwards grooving the vomer. The naso-palatines leave the nose through the foramina of Scarpa, the left nerve lying in front of the right one. On the palate they communicate with the anterior palatine.