58 TOPOGRAPHICAL ANATOMY OF THE 



The posterior end is retained in the fossa atlantis by loose fibrous tissue. 

 The anterior end is in contact with the anterior belly of the digastric 

 muscle. 



The duct of the submaxillary gland (ductus subinaxillaris) begins 

 by the union of numerous small radicles on the upper concave border of 

 the gland. Immediately on leaving the anterior end of the gland, the 

 duct is crossed laterally by the external maxillary artery. After crossing 

 the digastric tendon obliquely, it passes between the mylo-hyoid and 

 hyo-glossal muscles, in company with the hypoglossal nerve, to reach the 

 medial surface of the sublingual gland. The last part of its course is 

 immediately beneath the mucous membrane of the floor of the mouth, 

 and its termination is on an elongated fiatteued papilla {cariincida 

 sivb lingual is) on a level with the mandibular canine tootli. 



M. STYLOGLOSSUS. — The stylo-glossal muscle is elongated, narrow, 

 and flattened, and arises from the anterior part of the lateral surface of 

 the great cornu of the hyoid bone. Passing along the side of the tongue, 

 the fibres of the muscle slightly diverge and are lost in the substance 

 of that organ towards its tip. 



M. HY0GL0SSU8. — The hyo-glossal muscle is fiat and four-sided, and 

 lies to the side of the base of the tongue. It is crossed obliquely by 

 the stylo-glossal muscle. Its fibres spring from the thyroid process, the 

 body of the hyoid bone and its glossal process, and the lesser cornu. 

 They run obliquely upwards and forwards, and gradually disappear 

 in the substance of the tongue. 



M. GENIOHYOIDEUS. — The genio-hyoid ^ is a fusiform muscle placed 

 immediately within the mylo-hyoid, and running longitudinally parallel 

 to and in contact with its fellow muscle of the opposite side of the 

 head. Its origin is from the medial aspect of the mandible close to the 

 symphysis, and its insertion is into the glossal process of the hyoid bone. 



A. CAROTIS COMMUNIS. — The termination of the common carotid, 

 underneath the submaxillary gland and at the level of the inferior 

 border of the jugulo-mandibular muscle, is now exposed. The three 

 vessels into which the common carotid divides are the occipital and the 

 internal and external carotid arteries. Of these, the two first mentioned 

 will not be followed until later. The external carotid artery is not only 

 the largest of the three terminal branches : it is also that which, from 

 its direction, might be regarded as the direct continuation of the parent 

 vessel. 



A. CAROTIS EXTERNUS. — The external carotid artery may be con- 



' yiveiov (geneioii) [Or.], the ehiii. 



