MECKEL'S GANGLION AND ITS CONNECTIONS. 595 



2. The subcutaneous malar or orbital (o) supplies by its temporal and orbital 

 branches sensibility to the lateral angle of the eye and the adjoining area of skin 

 of the temple and cheek. Certain fibres are said to be the true secretory nerves for 

 tears. Compare N. lacrimalis, p. 591. 



3. The dental, anterior, posterior, and median, and with them the anterior fibres 

 from the infraorbital nerve, supply sensory fibres to the teeth in the upper jaw, 

 the gum, periosteum, and the cavities of the jaw (p. 592). The vaso-motor nerves 

 of all these parts are supplied from the upper cervical ganglion of the sympathetic. 



4. The infraorbital (R), after its exit from the infraorbital foramen, supplies 

 sensory nerves to the lower eyelid, the bridge and sides of the nose, and the upper 

 lip as far as the angle of the mouth. The accompanying artery receives its vaso- 

 motor fibres from the superior cervical ganglion of the sympathetic. For the 

 sweat-secreting fibres which occur in it (pig) see 288. 



The spheno-palatine ganglion (Meckel's n) forms connections with the second 

 division. To it pass two short sensory root-fibres from the second division itself, 

 which are called spheno-palatine. Motor fibres enter the ganglion from behind, 

 through the large superficial petrosal branch of the facial (J) ; and grey vaso- 

 motor fibres (v) from the sympathetic plexus on the carotid (the deep large petrosal 

 nerve). The motor and vaso-motor fibres from the Vidian nerve, which reach the 

 ganglion through the canal of the same name. 



Branches of the Ganglion. (1) The sensory fibres (N) which supply the roof, 

 lateral walls, and septum of the nose (posterior and superior nasal) ; the terminal 

 fibres of the naso-palatine pass through the canalis incisivus to the hard palate, 

 behind the incisor teeth. The sensory inferior and posterior nasals for the lower 

 and middle turbinated bones, and both lower nasal ducts, are derived from the 

 anterior palatine branch of the ganglion, which descends in the palato-maxillary 

 canal. Lastly, the sensory branches for the hard (p) and soft palate (p-^), and the 

 tonsils arise from the posterior palatine nerve. All the sensory fibres of the nose 

 (see also the Ethmoidal nerve), when stimulated, cause the reflex act of sneezing 

 ( 120). Preparatory to the act of sneezing, there is always a peculiar feeling of 

 tickling in the nose, which is perhaps due to dilatation of the nasal blood-vessels. 

 This dilatation is rapidly caused by cold, more especially when it is applied directly 

 to the skin. The dilatation of the vessels is followed by an increased secretion of 

 watery fluid from the nasal mucous membrane. Stimulation of the nasal nerves 

 also causes a reflex secretion of tears, and it may also cause stand-still of the 

 respiratory movements in the expiratory phase (Hering and Kratschmer) (compare 

 Respiratory centre, 368). (2) The motor branches descend in the posterior palatine 

 nerve through the small palatine canal, and give off (A) motor branches to the 

 elevator of the soft palate and azygos uvulae (Nuhn). The sensory fibres for these 

 muscles are supplied by the trigeminus. According to Politzer, spasmodic con- 

 traction of these muscles occasionally causes crackling noises in the ears. (3) The 

 vaso-motor nerves of this entire area arise from the sympathetic root, i.e., from the 

 uppeF cervical ganglion. (4) The root of the trigeminus supplies the secretory 

 nerves of the mucous glands of the nasal mucous membrane. Stimulation excites 

 secretion, while section of the trigeminus diminishes it with simultaneous atrophic 

 degeneration of the mucous membrane. Thus, trophic functions for the mucosa 

 have been ascribed to the trigeminus (Aschenbrandt). 



Stimulation of the Ganglion. Feeble electrical stimulation of the exposed ganglion causes a 

 copious secretion of mucus and an increase of the temperature in the nose (Provost), with dila- 

 tion of the vessels (Aschenbrandt). [Meckel's ganglion has been excised in certain cases of 

 neuralgia ( JValsham). ] 



III. Inferior Maxillary (g). It contains all the motor fibres of the fifth, along 

 with a number of sensory fibres ; it gives off 



1. The recurrent, which springs by itself from the sensory root, enters the skull 



