238 ANATOMY OF THE RABBIT. 
In addition to the tributaries described above, the anterior 
facial vein receives from beneath the anterior margin of the 
masseter the deep facial vein (v. facialis profunda). The latter 
arises in the lower anterior portion of the orbit, and passes down- 
ward beneath the masseter muscle. The anterior facial vein 
receives at the ventral border of the mandible the internal max- 
illary vein (v. maxillaris interna). The latter also begins in the 
orbit, where it is connected with the deep facial. At the medial 
surface of the mandible it receives the inferior alveolar vein—to 
be seen at a later stage—from the interior of the mandible. 
The external jugular vein may be divided and turned forward together with 
the parotid gland. 
4. Examination of the more superficial structures of the ventral 
surface of the head and neck. 
(a) The submaxillary gland (gl. submaxillaris), one of the 
salivary series, a somewhat compact rounded or oval gland 
lying at the medial side of the extreme ventral portion of the 
angle of the mandible. Its whitish-colored duct (d. sub- 
maxillaris) may be seen running upward and slightly for- 
ward to enter the mouth. It crosses the lateral surface of the 
digastric muscle but is medial to the external maxillary 
artery. 
(b) The angle of the mandible is covered by two muscles of 
mastication, the masseter lying on the lateral surface, and 
the pterygoideus internus on the medial surface. 
(c) The digastricus. Only its insertion portion is visible. It 
passes forward along the medial surface of the mandible, to 
the anterior portion of which it is attached. 
(d) The mylohyoideus is a transverse sheet of muscle arising 
from the medial surface of the mandible on either side and 
inserted on the hyoid bone. 
(e) The sternomastoideus. Origin: In common with that 
of the opposite side, from the manubrium sterni. Insertion: 
Mastoid process of the skull. 
(f) The sternohyoideus. Origin: In common with that of the 
opposite side, from the dorsal surface of the manubrium and 
anterior portion of the body of the sternum, extending to the 
third costal articulation. Insertion: Greater cornu of the 
hyoid. 
