Page 280 - My FlipBook

290 ANATOMY.
the frontal sinus and ethmoidal cells are described by Meckel and
Lansrenbeck." ^

Superior Maxillary Nerve.
The superior maxillary or second division of the fifth nerve is the
second in size of its three great divisions. It is composed entirely of
sensory fibres, and gives sensation to nearly all the structures of and
around the superior maxillary bone. It commences in the centre of the
conv'ex or anterior margin of the Gasserian ganglion by a flattened and
plexiform band, passes horizontally and directly forward, and leaves the
cranium through the foramen rotunduni in the great wing of the sphe-
noid bone. It then enters the pterygo-maxillary (spheno-maxillary)
fossa, and becomes more rounded and firmer in texture. It passes across
this fossa surrounded by adipose tissue, and enters the infraorbital or
superior maxillary canal, and receives the name of infraorbital nerve. It
passes through this canal, and emerges upon the face through the infra-
orbital foramen. The branches of this nerve can be divided into lour
groups, according to the locality of their origin.
The Orbital or Temporo-malar Branch (subcutaneous malse) is a
small nerve which arises from the upper ])ortion of the superior max-
illary nerve just after it emerges from the foramen rotundum. It passes
forward into the orl)ital cavity through the spheno-maxillary fissure,
and immediately divides into two branches, temporal and malar.
The Temporal Branch passes forward in a groove on the outer wall
of the orbit until it reaches the temporal canal in the malar bone. It
passes through this canal into the anterior portion of the temporal fossa,
ascends between the bone and the tem])oral muscle a short distance,
pierces the muscle and its aponeurosis about an inch above the zygoma,
and terminates in filaments which supply the cutaneous structures of
the temporal region and the side of the forehead. It interlaces with
the facial and occasionally with the third division of the fifth nerve.
That portion of the nerve within the orbit sends one or two filaments
of communicatiiMi to the lachrymal nerve, a branch of the ophthalmic
division of the fifth.
TJte Malar Branch at its commencement ])asses through the loose
adipose tissue at the lower angle of the orbit to the malar bone, through
which it extends in the malar canal in its lower portion, and emerges
upon the face usually by two branches. It is distributed to the cutaneous
tissues in this region of the cheek, and interlaces with the facial nerve.
TJtc Sij/ic)io-j)alafi))P Branches are usually two in number, and are
given off from the middle of the lower surface of the pterygo-maxillary
portion of the second division of the fifth nerve. They pass downward
to the spheno-palatine or Meckel's ganglion.
The Posterior I'^tiperior Dental or Alveolo-dental Nerve usually arises
by one root, though occasionally it has two, from the second division of
the fifth nerve just l)efi)re it passes into the infraorbital canal. When
it arises by one root it almost immediately divides into two, and forms
a superior and an inferior set of branches.
^ From Quain's Anatomy.