Page 299 - My FlipBook

THE NERVOUS SYSTEM. 309
the following muscles : attrahens and attolens aurem, frontalis, part of
the orbicularis palpebrarum, and the corrugator supercilii. It commu-
nicates with the three divisions of the fifth nerve, the auriculo-temporal,
a branch of the inferior dental, the temporal branch of the superior
maxillary, and the supraorbital and lachrymal branches of the oph-
thalmic nerve.
The Malar or Ocular Branch passes forward, inward, and slightly
upward to reach the external portion of the orbital cavity, and is dis-
tributed to the orbicularis palpebrarum and the corrugator supercilii.
On the upper eyelid communicating filaments of this nerve inter-
lace with the lachrymal and supraorbital branches of the ophthalmic,
while on the lower eyelid they communicate with branches of the
infraorbital.
The Infraorbital or Tramverse Branch is larger than the other two
divisions. It passes nearly horizontally forward and inward over the
masseter muscle to the space between the orbit and the mouth, and
divides into a superficial and deep set of branches.
The Sujjerfeial set passes between the integument and the muscles of
the face
; its filaments are distributed to the zygomatic, levator labii
superioris alsequse nasi, and the small nasal muscles.
The Deep Set passes beneath the levator labii superioris, and is dis-
tributed to the levator anguli oris and buccinator muscles. The termi-
nal filaments of this set of nerves interlace with the filaments of the
infraorbital and superior maxillary and infratrochlear nerves to form
the infraorbital plexus, which is situated beneath the levator labii supe-
rioris proprius.
The Cervico-facial Branch is smaller than the temporo-facial, and
passes obliquely downward and forward through the substance of the
parotid gland to the angle of the inferior maxillary bone. It then
extends on to the face below the other divisions of the fiicial nerve, and
passes to the superior portion of the neck. At the angle of the jaw it
terminates by dividing into three branches, buccal, supramaxillary, and
cervical. When this nerve is within the parotid gland it receives a
communicating filament from the great auricular nerve of the cervical
plexus.
The Buccal Nerve in the first portion of its course passes between the
parotid gland and the masseter muscle, then extends over the muscle in
the direction of the angle of the mouth. It is distributed to the bucci-
nator, palato-glossus and orbicularis oris, and receives communicating
branches from the buccal and temporo-facial divisions of the inferior
maxillary nerve.
The Supramaxillary Nerve is often double—that is, it is represented
by two distinct nerves. It passes forward along the deej) surface of
the depressor anguli oris, and is distributed to the muscles of the
lower lip and chin, A branch from this nerve extends forward along
the margin of the lower jaw to the symphysis inenti. It communicates
with the mental branches of the inferior dental nerve and a branch from
the inferior maxillary division of the fifth nerve.
The Cervical Nerve (inframaxillary) passes downward and forward,
pierces the deep cervical fascia, and breaks up into slender bi'anches