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THE NERVOUS SYSTEM. 293
nal pterygoid muscle, then curves upward, running close to the temporal
bone, and is distributed to the deep and internal portions of the temporal
muscle.
The Posterior Temporal Branch is made up entirely of motor fila-
ments. During the first portion of its course it is often associated with
the masseteric nerve. It passes in a tortuous manner upward and out-
ward, then ujjward through the proximal surface of the temporal mus-
cle ; it passes out of this muscle and through its fascia from a half to
three-quarters of an inch above the zygoma, and then turns upAvard
beneath the skin and interlaces with the auriculo-temporal and facial
nerves.
The Masseteric Nerve is larger than the deep temporal, and arises in
Occasionally these two nerves arise as a common
close proxiiuitv to it.
trunk from the third division of the fifth nerve. It passes backward
and outward between the upper portion of the zygomatic fossa and the
superior border of the external pterygoid muscle, curves slightly down-
ward and outward, and passes tlirough the sigmoid notch in the inferior
maxillary bone. It then extends downward between the ramus of the
bone and the masseter muscle, to which muscle it is mainly distributed.
Its other branches of distribution are, first, a small communicating fila-
ment which interlaces with the deep temporal and independent deep
posterior temporal branch, and an articulating branch which passes to
the temporo-maxillary articulation.
The Internal Pterygoid Nerve is the shortest branch of the third
division of the fifth nerve. It is given off from its anterior and prox-
imal side on a level with the otic ganglion. It passes backward between
the ganglion and the lingual nerve, occasionally extending through the
ganglion to the inner side of the internal pterygoid muscle, to which
it is mainly distributed. Its other branches of communication are,
first, a motor root to the otic ganglion ; second, a filament to the palato-
Eustachian (tensor palati) muscle ; third, a branch to the tensor tym-
pani.
The External Pterygoid Nerve is not constant in its origin ; it seldom
arises from the main trunk of the inferior maxillary, but generally in
conjunction with the buccal branch or from the internal pterygoid
nerve. It is distributed to the external pterygoid muscle.
The Buccal Nerve, though described under the head of the motor
branches of the inferior maxillary nerve, is almost entirely composed
of sensory fibres. It arises from the lateral margin of the main trunk
of the inferior maxillary by from one to three bundles, and is usually
joined at its origin by the anterior deep temporal and the external
pterygoid nerves. It passes outward, either between the two heads of
the external pterygoid or between the tMO pterygoid muscles ; extends
downward to the inner surface of the coronoid process of the inferior
maxilla, thence forward between this process and the tuberosity of the
superior maxillary bone, occasionally passing between the fibres of the
temporal muscle close to its insertion. Midway between the lobe of the
ear and the angle of the mouth it becomes superficial, and terminates by
dividing into superior and inferior branches.
Branches of distribution are
THE NERVOUS SYSTEM. 293
nal pterygoid muscle, then curves upward, running close to the temporal
bone, and is distributed to the deep and internal portions of the temporal
muscle.
The Posterior Temporal Branch is made up entirely of motor fila-
ments. During the first portion of its course it is often associated with
the masseteric nerve. It passes in a tortuous manner upward and out-
ward, then ujjward through the proximal surface of the temporal mus-
cle ; it passes out of this muscle and through its fascia from a half to
three-quarters of an inch above the zygoma, and then turns upAvard
beneath the skin and interlaces with the auriculo-temporal and facial
nerves.
The Masseteric Nerve is larger than the deep temporal, and arises in
Occasionally these two nerves arise as a common
close proxiiuitv to it.
trunk from the third division of the fifth nerve. It passes backward
and outward between the upper portion of the zygomatic fossa and the
superior border of the external pterygoid muscle, curves slightly down-
ward and outward, and passes tlirough the sigmoid notch in the inferior
maxillary bone. It then extends downward between the ramus of the
bone and the masseter muscle, to which muscle it is mainly distributed.
Its other branches of distribution are, first, a small communicating fila-
ment which interlaces with the deep temporal and independent deep
posterior temporal branch, and an articulating branch which passes to
the temporo-maxillary articulation.
The Internal Pterygoid Nerve is the shortest branch of the third
division of the fifth nerve. It is given off from its anterior and prox-
imal side on a level with the otic ganglion. It passes backward between
the ganglion and the lingual nerve, occasionally extending through the
ganglion to the inner side of the internal pterygoid muscle, to which
it is mainly distributed. Its other branches of communication are,
first, a motor root to the otic ganglion ; second, a filament to the palato-
Eustachian (tensor palati) muscle ; third, a branch to the tensor tym-
pani.
The External Pterygoid Nerve is not constant in its origin ; it seldom
arises from the main trunk of the inferior maxillary, but generally in
conjunction with the buccal branch or from the internal pterygoid
nerve. It is distributed to the external pterygoid muscle.
The Buccal Nerve, though described under the head of the motor
branches of the inferior maxillary nerve, is almost entirely composed
of sensory fibres. It arises from the lateral margin of the main trunk
of the inferior maxillary by from one to three bundles, and is usually
joined at its origin by the anterior deep temporal and the external
pterygoid nerves. It passes outward, either between the two heads of
the external pterygoid or between the tMO pterygoid muscles ; extends
downward to the inner surface of the coronoid process of the inferior
maxilla, thence forward between this process and the tuberosity of the
superior maxillary bone, occasionally passing between the fibres of the
temporal muscle close to its insertion. Midway between the lobe of the
ear and the angle of the mouth it becomes superficial, and terminates by
dividing into superior and inferior branches.
Branches of distribution are
