132 THE VOYAGE OF H.M.S. CHALLENGER. 



Attachments. — The pterygoid muscle is of great size. It arises from the posterior 

 extremity of the lower jaw bone, behind the articulation of that bone with the os 

 quadratum, its fibres being attached to the outer, inner, and lower surfaces of the bone. 

 The fibres pass obliquely forwards, upwards, and inwards, and are imerted into the lower 

 surface of the pterygoid bone, as well as into the whole length of the lower surface and 

 external margin of the palate bone. The external fibres of the muscle are to some extent 

 separated from the rest by connective tissue, and are inserted by means of a stout tendon 

 into the anterior extremity of the palate bone, close to the articulation of the latter with 

 the superior maxillary bone. 



Action. — This muscle approximates the upper and lower jaws, and assists in closing 

 the mouth. 



Relations. — The origin of this muscle lies immediately in front of that of the retractor 

 linguae. At its insertion it is in contact with its fellow of the opposite side, and is 

 concealed by the papillated mucous membrane of the roof of the mouth. 



Nerve supply (?) 



4. Orhito-maxiUaris. 



Der Augenhohlenkiefcrmuskel, "Wiedemann, p. 73. 



Der AugenholilKii-Unterkiefer-Mu^lcel, Tiedemaiin, p. 387, Xo. 4. 



La quatrihme portion du masseter, Cuvier, vol. iii. p. 7L 



Attachments. — The orbito-maxillary muscle arises from the lower surface of the skull, 

 below a ridge extending from the post orbital process, obliquely backwards and downwards 

 to the quadrato-temporal articulation. The muscle is triangular in form, and terminates 

 on a strong tendon, which is inserted into a well-marked tubercle on the inner surface of the 

 lower jaw, immediately in front of the articular surface of that bone. 



Action. — This muscle, in conjunction with the temporal, elevates the lower jaw. 



Relations. — The orbito-maxillaris is concealed superficially by the temporal muscle, 

 the inferior maxillary nerve passing forwards between them. 



Nerve stiiyphj (?) 



Remarhs.— This, muscle is not described by Gervais and Alix, who have doubtless 

 regarded it as a portion of the temporal muscle. It is, however, quite distinct from the 

 latter, being separated from it by the inferior maxillary nerve. 



5. Quadrato-maxillaris. 



Der Qiiadratknochen-Unterhiefer-M'uskel, Tiedemann, p. 383, No. 5. 



Der Gelenkheinkiefervniskel, Wiedemann, p. 73. 



Muscle No. 2, Meckel, vol. viii. p. 161. 



Le premier muscle exteh-ne de I'os quarre, Cuvier, vol. iii. p. 73. 



Attachments. — The quadrato-maxillaris is a small muscle, which arises from the 



