Drxon—On the Development of the Branches of the Fifth Cranial Nerve in Man. 75 
Figure 
18. Drawing of a reconstruction to illustrate the superior maxillary nerve in embryo CR. This 
drawing corresponds to a portion of a horizontal section through the head, 0°6 mm. in thickness, 
x 25 diameters, seen from above. The loose arrangement of the bundles of fibres of the superior 
maxillary nerve, at this stage, is shown. Meckel’s ganglion, which is placed to the inner side of 
the superior maxillary nerve, is only very slightly connected in this nerve. Meckel’s ganglion 
has a process which passes in between the cartilages of the basis cranii towards the Gasserian 
ganglion. The Vidian nerve is connected with the lower part of Meckel’s ganglion, some of its 
fibres ending in it, while the rest of the nerve is continued upwards and forwards towards the 
root of the primitive mouth-cavity. A portion of the sixth nerve is seen crossing the carotid 
artery. The roof of the primitive mouth-cavity with the choane is shown 
14. Drawing of a reconstruction illustrating the inferior maxillary nerve in embryo Br;. This drawing 
corresponds to a horizontal section through the head, 0-28 mm. in thickness, x 25 diameters, seen 
from above. The nerve present in this stage is found to represent the inferior dental nerve of the 
adult. The Gasserian ganglion, with its motor and sensory roots, is seen in section. The 
opening of the primitive mouth on to the face is seen. 
15. Drawing of a reconstruction to illustrate the inferior maxillary nerve in embryo Ru. The drawing 
corresponds to a portion of a horizontal section through the head, 0:6 mm. in thickness, x 25 
diameters, seen from above. The lowest part of the Gasserian ganglion lies in this section, and 
taking origin from it are the sensory fibres of the inferior maxillary nerve. The motor root is 
seen crossing the main nerve from within outwards. The direction of the inferior maxillary 
nerve is forwards and downwards, but finally it turns somewhat inwards, in front of Meckel’s 
cartilage. The whole nerve (omitting the motor fibres) present in this stage, probably represents 
the inferior dental nerve of the adult. The small branch given off towards the back of Meckel’s 
cartilage appears to represent the communication found in the adult between the inferior dental 
and lingual nerves. The facial nerve and its geniculate ganglion are seen lying deeply in the 
section; the Eustachian tube passing outwards, between the facial and the inferior maxillary nerve. 
From the facial nerve the chorda tympani branch passes upwards, and ends near the small branch 
of inferior maxillary, behind Meckel’s cartilage. The first part of the great superficial petrosal 
nerve is seen taking origin from the geniculate ganglion, and turning inwards towards the 
carotid artery; the nerve then has a more vertical course, lying not far from the carotid 
artery. 
16. Drawing of a reconstruction illustrating part of the inferior maxillary nerve in embryo CR. The 
drawing corresponds to portion of a horizontal section through the head, 0:3 mm. in thickness, 
x 25 diameters, seen from above. The inferior maxillary nerve is seen taking origin from the 
Gasserian ganglion, and the crossing of the sensory fibres by the motor root is also shown. 
Immediately in front of this crossing the long buccal is seen to take origin. Only the proximal 
and terminal parts of this nerve are shown, as the intermediate part lies above the level of the 
section. The terminal part comes forwards towards the angle of the primitive mouth. The 
inferior maxillary nerve divides after a very short course into lingual and inferior dental 
branches ; these are however connected further on by a very distinct communicating branch. 
These two nerves are finally separated by the inner end of Meckel’s cartilage. The lingual 
nerve enters the submaxillary ganglion. The otic ganglion lies to the inner side of the motor 
root of the fifth nerve. Passing upwards and forwards on the inner side of the otic ganglion we 
have the great superficial (Vidian) branch from the facial. The roots and ganglion of the 
seventh nerve, which should lie in the upper part of this section, partly under cover of the 
Gasserian ganglion, have been omitted. 
TRANS. ROY. DUB. SOC., N.S. VOL. VI., PART IT, M 
