212 



HUMAN ANATOMY. 



ment to the mylo-hyoid, which forms the muscular partition separating . the oral 

 cavity from the superficial region under the chin. There is a faint hollow, the sub- 

 lingual fossa, above it, below the incisors, for the sublingual gland lying beneath the 

 mucous membrane, and a deeper one, the submaxillary fossa, for the submaxillary 

 gland below the line near the junction of the body and ramus. 



The ramus, which joins the body at an angle of from iio° to 120° in the 

 adult is a four-sided plate with an outer and an inner surface. The point of union 

 of the posterior and inferior borders is called the angle, and is generally turned out- 

 ward with a lip, which helps to form the under part of the viasseterie fossa, on its 

 outer side, for that muscle. When well marked, it represents the fossa which is so 

 striking in the carnivora and some other orders. The fossa is not always present, 

 the muscle being then inserted into a roughness. At the front of this space the 

 lower border of the bone is often grooved by the facial artery crossing it. A projec- 

 tion known as the lemiirme process, may extend from the angle either backward or 

 downward, but is not often large. The lower border of the ramus, where it joins 

 the body, often presents a concavity, which is sometimes very marked, giving a 

 peculiar outline ; it is named the antegonium by Harrison Allen. There is a rough- 



FiG. 242. 



Coronoid process 



Sigmoid notch 



Superior constrictor 

 Alveolar border 



Fossa for sublin- 

 gual glandi 



Sup. genial tuber. 



(genio-glossiis) 



Inf. genial tuber. 



(genio-liyoid) 



Condyle 



Ext. pterygoid 



Neck 



Lingula 



Inferior dental 

 foramen 



Mylo-hyoid 

 groove 



Int. pterygoid 



Digastric 



Mylo-hyoid Subnia.xillary gland 



Inferior maxillarj* bone, inner aspect. 



ness on the inner side of the ramus at the angle for the internal pterygoid. About 

 on a line with the free edge of the alveolar process is the lowest point of the inferior 

 dental foramen ,^ an opening into the inferior de7ital canal for the nerve and artery to 

 the teeth ; the foramen is guarded in front by a sharp point, the lingula. A faint 

 groove is continued from this opening below the internal oblique line for the mylo- 

 hyoid vessels and nerve. The front border of the ramus is thick below and narrow 

 above, where it becomes the coronoid process,'^ pointing upward and outward, into 

 which the temporal muscle is inserted. The outer border of the thick part is made 

 by the external oblique line, which is continued into the thin edge above ; the inner 

 border is continued from the inner edge of the alveolar process, or sometimes from 

 the internal oblique line. It ends on the inner surface of the coronoid process. 

 The posterior border of the ramus slants upward, backward, and a little outward. 

 It is rough at the angle and smooth above, where it widens to form the back of the 

 head or condyle} This presents an articular surface convex from before backward 

 and higher at the middle than at the ends. The longest diameter is not quite trans- 

 verse, for the axes, if prolonged, would meet near the front of the foramen magnum. 

 There is a pretty distinct tubercle at the outer and inner ends. The condyle has 



* Foramen mandibulare. ' Processus coronoidcus. '' Capitulum mandibulae. 



