THE MAJ^DIBLE 



71 



glossus muscles. On the vertical part the surface is concave, and is marked in its 

 lower and posterior part by rough lines for the attachment of the medial pterygoid 

 muscle. In front of its middle is the mandibular foramen (Foramen mandibulare),' 

 which is the posterior orifice of the mandibular canal (Canalis mandibula;) .^ The 

 canal curves downward and passes forward below the cheek teeth, opening exter- 

 nally at the mental foramen; it is continued into the body of the bone as a small 

 canal (Canalis alveolaris incisivus), which carries the vessels and nerves to the 

 incisor teeth. The dorsal or alveolar border (Limbus alveolaris) forms anteriorly 

 part of the interalveolar space; here it is thin. Behind this it is thick and is ex- 

 cavated by six alveoU for the lower cheek teeth. Behind the last alveolus it curves 

 sharply upward and is narrow and rough. In the young foal there is commonly a 

 small alveolus for the vestige of the first premolar ("wolf tooth") close to the first 

 large one. The ventral border of the horizontal part is nearly straight; it is thick 

 and rounded in the j-oung horse, becoming narrower and sharp in old subjects. At 



Fig. 45. — Left Half of Mandible of Horse; Medial View. 

 1, Body of mandible (median section); 2, 2', horizontal and vertical parts of ramus: .3, interalveolar border; 4, 

 depression for attachment of genio-hyoideus muscle; 5, mandibular foramen; 6, vascular impression; 7, angle; 8, 

 condyle; 9, coronoid process; 10, mandibular notch; 11, incisor teeth; 12, canine tooth; 13, cheek teeth. 



its posterior part there is a smooth impression (Incisura vasorum) where the facial 

 vessels and parotid duct turn round the bone. Behind this point the border curves 

 sharply upward, forming the angle of the mandible (Angulus mandibulse) ; this part 

 is thick and has two roughened lips, separated by a considerable intermediate space; 

 near the condyle it becomes narrower. The anterior extremity joins the body. 

 The articular extremity comprises the coronoid process in front and the condyle 

 behind, the two being separated by the mandibular notch (Incisura mandibulae), 

 through which the nerve to the masseter muscle passes. The coronoid process 

 (Processus coronoideus) is thin transversely and curved sUghtly medially and 

 backward. It projects upward in the temporal fossa and furnishes insertion to 

 the temporal muscle. The condyle of the mandible (Condylus mandibulse) lies at 

 a much lower level than the end of the coronoid process. It is elongated trans- 

 versely and articulates with the squamous temporal through the medium of an 



1 This is also commonly called the inferior maxillary foramen. 

 " This is also termed the inferior dental canal. 



