BRAIN 55 
V. NV. trigeminus is next to the optic the thickest nerve, and of 
a complex nature, being motory and sensory. It arises from the 
sides of the mid- and hindbrain, forms the large Gasserian ganglion 
in the wall of the cranium, and leaves the latter in the form of three 
branches. ‘The first or ophthalmic branch comes directly out of the 
ganglion through a foramen behind the optic (II), runs along the 
dorsal corner of the orbital septum, and leaves the orbit at its 
inner anterior corner in order to supply the palate, the bill, fore- 
head, and the lacrymal gland. It is chiefly sensory, and con- 
sequently strongest in birds with tactile bills, like Ducks and 
Snipes. The second or upper maxillary branch runs along the 
ventral edge of the orbital septum, and besides the palatine and 
maxillary regions supplies the eyelids and Harder’s gland. The 
third or inferior maxillary branch is the strongest of the three; it 
leaves the cranium together with the second through a foramen 
between the basi-alisphenoid and petrosal bones and innervates all 
the masticatory muscles, the parotid gland, and the whole of the 
under jaw. 
VI. NV. abducens is a very thin nerve arising from the hindbrain 
near the medio-ventral line, entering the orbit through a special 
foramen latero-ventrally from the optic foramen, and supplying the 
m. rectus externus and the two muscles of the nictitating membrane. 
It is entirely motory. 
VIL. WV. facialis arises from the side of the hindbrain, possesses 
a ganglion (g. geniculatum), passes through the petrosal bone into 
the Fallopian canal, and sends the sympathetic sphenopalatine branch 
to the second branch of the trigeminal nerve (V). The facial nerve 
leaves the tympanic cavity behind the quadrate bone, supplies the 
digastric muscle or depressor of the mandible, the little stapedius 
muscle of the ear-bones, the mylo- and stylohyoid muscles of the 
tongue, and further on connects itself with branches from the first 
four cervical nerves and occasionally with branches from the glosso- 
pharyngeal nerve (IX), ultimately supplying the skin on the front of 
the neck. There are no branches, as in Mammals, to supply the 
face, nor is there in Birds a chorda tympani, #.e. a branch of the 
facial nerve joining the mandibular branch of the trigeminal nerve(V). 
VIII. NV. acusticus arises dorsally from the facial nerve (VII), 
of which it is the sensory portion. It is very short and thick, 
possesses a little ganglion, and spreads out in the cochlea of the Ear 
as the nerve of hearing. 
IX. N. glossopharyngeus takes its origin from the dorso-lateral 
sides of the medulla oblongata, near the rhomboid fossa. It leaves 
the cranium through the foramen jugulare, which lies between the 
petrosal and the lateral occipital bones, and also serves as exit for 
the vagus nerve (X) and the jugular vein. Here the ninth nerve 
forms a big swelling, the ganglion jugulare, and is connected with the 
