930 THE OSTEOLOGY AND MYOLOGY OF THE DEATH ADDER, 



Posterior border : The posterior border gives insertion to the 

 depressores costarum. At its middle point, and just external to 

 this, we have the origin of the transverse muscle, and still more 

 external the insertion of the retrahentes costarum. The external 

 extremity gives attachment to the costal cartilages, which give 

 origin to the internal oblique, and the antero-posteriorly directed 

 fibres of the external intercostal muscles. 



Myology. 



Muscles of the Head. 



On the integument being reflected from the cephalic region the 



muscles of the head are displayed covered only by a delicate 



fascia, which runs forward to be lost on the frontal bones. In the 



mid-line the greater portion of the median triangle of the parietal 



bone is to be seen uncovered by muscle. On either side anteriorly 



lie the masseters resting on the venom gland beneath, and covering 



the anterior, and portion of the posterior, temporal muscles. 



Posteriorly the quadrilateral-shaped digastric runs outwards and 



backwards to the extremity of the mandible, where it is covered 



by the fibres of the retractor oris as they run from the neural 



spines downwards and forwards to end at the symphysis of the 



lips. Inserted on to the supraoccipital is seen the spinalis dorsi, 



while on the exoccipital of either side is the complexus. Posterior 



to the retractor oris the depressor mandibulse springs, and runs 



forward and downwards to merge into the mylohyoid between the 



mandibles below. 



Masseter. 



M. ^;ar^eto^^-g"^*acZra<o-?;^a?^c?^6^^^ar^s {seine vordere Portion)^ 

 Hofi'mann ; Schliesser des Mauls oder Beissmuskeln, Hiibner ; 

 Der grosse Beiss- oder Shlafenmuskeln {seine vordere Portion), 

 D' Alton; M. temporalis, von Teutleben ; Masseter, Owen; 

 Temporalis anterior, Duvernoy, R. Jones. 



The masseter arises from the lower two-thirds of the external 

 surface of the postorbital bone, and from the upper portion of 

 the lateral triangle on the superior surface of the parietal. The 



