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BLOOD-VESSEL SYSTEM OF THE HEAD, ETC. 253

tinue downwanl and pass forward in front of the ear to a point just
above the zygoma, where it joins the middle temporal vein.
The INIiDDLE Temporal Vein originates in a plexus of veins situ-
ated in the temjjoral muscle. This plexus communicates with the deep
temporal veins as well as with the pterygoid plexus. The vein then
passes out of the muscle through the temporal fascia, and joins the
superficial temporal vein just above the base of the zygoma. Its orbital
branch originates from the union of a number of the external palpe-
it inosculates with the supraorbital and facial veins, passes
bral veins ;
backward, and terminates in the middle temporal vein.
The Parotid Veins are small vessels which pass from the parotid
gland and empty into the common temporal vein.
The Articular A-^eins pass from the temporo-maxillary articula-
tion and terminate in the common temporal vein.
The Anterior Auricular Vein passes from the external ear and
empties into the common temporal vein.
The Transverse Facial Vein returns the blood from the region
supplied by the transverse facial artery, and inosculates with the facial
and infraorbital veins.
The Internal Maxillary or Posterior Facial Vein orig-
inates in a large plexus of veins which is situated betMeen the temporal
and external pterygoid muscles, as well as partly between the two
pterygoid muscles. It passes backward and outward, accompanied by
the internal maxillary artery, enters the parotid gland, and terminates
by emptying into the temporo-maxillary vein about halfway between
the zygoma and the angle of the jaw. The plexus from which the
internal maxillary vein originates is formed by numerous tributaries
which arise from the region supplied by the internal maxillary artery.
These tributaries are the infraorbital, which commences on the face and
anastomoses with the veins below the eye, and passes backward through
the infraorbital canal and the spheno-maxillary fissure to join the ptery-
goid plexus ; the posterior dental or alveolar, which commences on the
surface of the superior maxilla and the jiosterior superior teeth ; the
superior palatine, spheno-palatine, and Vidian, which pass through
the foramina indicated by their names to join the plexus ; the infe-
rior dental, which commences on the chin, receiving branches from
the lower incisor teeth, and passes backward along the inferior dental
canal, and emerges from the jaw at the posterior dental foramen, AAhere
it is joined by the mylo-hyoid vein. It then passes directly upward to
the deep temporal veins, three or four in number, descend
the plexus ;
to the plexus. There are also other muscular branches, such as the
pterygoids, masseteric, and buccal, as well as a communicating branch
from the inferior ophthalmic vein, which join the plexus. The middle
meningeal veins are also tributaries. They are two in number, and are
the vense comites of the middle meningeal artery. They originate
wnthin the dura mater of the brain and inosculate with the cavernous
sinus.
The Posterior Auricular Vein is much larger than the artery
of the same name. It originates in a plexus formed by small veins
situated at the posterior portion of the side of the head. This plexus