ANATOMY IN A NUTSHELL. 5 !•'• 



hyoid vessels and nerve. The Internal pterygoid muscle is attached to a rough 

 surface behind this groove. The lingula is a sharp spine at the anterior margin 

 of the mental foramen and gives attachment to the internal lateral ligamenl of 

 the jaw. 



The anterior border of the ramus is a continuation of the external 

 oblique line. 



The superior border of the ramus has the coronoid process anteriorly, 

 the deep sigmoid notch in the center, and the condyle of the lower jaw pos- 

 teriorly. The deep sigmoid notch is crossed by the masseteric vessels and 

 nerve. 



The posterior border, which is thick and rounded, is saddled by the 

 parotid gland. 



The inferior border is continuous with the body. 



The angle of the jaw is the junction of the posterior border and the in- 

 ferior border. On the lower part of the posterior border between the Masseter 

 muscle externally and the Internal pterygoid muscle internally is the attach- 

 ment of the stylo-maxillary ligament. 



The inferior dental canal, which is for the inferior dental vessels and nerve, 

 passesfrom thedental foramen in the ramusof the bone downward and forward. 

 It now turns forward to pas- underthe alveoli in the body of thebone as far as 

 the incisor teeth. It gives off a branch to the mental foramen. This canal 

 lies near the internal surface of the bone for its first two-thirds, and near the 

 external surface 'for its anterior one-third. 



The coronoid process, which is at the anterior margin of the upper border 

 of the ramus, is thin. flat, and triangular. It gives attachment to the Tem- 

 poral muscle on both its external and interna] surface-. 



The condyloid process is situated at the posterior margin of the superior 

 border of the ramus. Its condyle, winch has its long axis transversely and 

 its outer end higher and more anterior than the inner, articulates with the 

 glenoid fossa of the temporal bone. The neck of the condyloid process receives 

 the insertion of the External pterygoid muscle internally. There is a tubercle 

 on its external margin for the capsular and external lateral ligamenl of the 

 lower jaw. 



Ossification. — This bone ossifies from twelve centers; six for each lateral 

 half. 



Articulation. — It articulates with the glenoid fossa' of the two temporal 



bone-. 



Attachment of Muscles. Thee are fifteen pairs of muscles attached to 

 this hone. To the kames. the Masseter of the teniporo-niaxillarv region, the 

 Internal pterygoid and External pterygoid of the pterygo-maxillary region, 

 and Temporal of the temporo-maxillary region; to internal surfaci 

 ok 'nil-: body, the Genio-hyo-glossus and Genio-hyoideus of the lingual region, 

 Mylo-hyoid of the supra-hyoid region, Digastric of the supra-hyoid region, and 

 Superior constrictor of the pharynx : ro the extern ^l surfaci of the body, 

 Depressor lahii Lnferioris and Depressor anguli oris of the inferior maxillary 

 region, Levator menti of the inferior maxillarv region. Orbicularis oris of the 



