THE HEAD AND NECK i loi 



and backwards beneath the stemo-cleido-raastoid, the deep portion 

 of which it pierces. 



Digastric or Submaxillary Triangle. — ^This triangle is divided into 

 two parts, anterior and posterior, by the stylo-mandibular liga- 

 ment. The anterior part contains the superficial part of the sub- 

 maxillary gland, the facial vein being superficial to it, and the 

 facial artery being embedded in its upper and back part. In this 

 triangle the facial artery gives off its inferior or ascending palatine, 

 tonsillar, glandular, and submental branches. The muscles in the 

 floor of the anterior part of the triangle are the mylo-hyoid, 

 and a part of the hyo-glossus. The superficial part of the sub- 

 maxillary gland rests upon the mylo-hyoid muscle, and conceals 

 the mylo-hyoid nerve and submental artery, which are in direct 

 contact with the muscle. The hypoglossal nerve lies upon that 

 part of the hyo-glossus muscle which appears in the anterior part 

 of the triangle, but it soon disappears beneath the posterior free 

 border of the mylo-hyoid muscle, in company with the deep part of 

 the submaxillary gland and the lingual nerve. The posterior part 

 of the digastric triangle contains a portion of the parotid gland, 

 and under cover of this part is the external carotid artery, which 

 here furnishes its posterior auricular branch. 



The anterior jugular vein and the superficial or transverse cer- 

 vical neri'e have been already described (see pp. 1083 and 1093). 

 The inframandibular branch of the facial nerve will be found 

 described on p. 1175. 



Submaxillary Lymphatic Glands. — These glands lie upon the super- 

 ficial surface of the submaxillary salivary gland, under cover of the 

 deep cervical fascia. They form a chain beneath the corresponding 

 half of the base of the mandible, which extends from near the angle 

 of the bone to near the origin of the anterior belly of the digastric 

 muscle. The central gland of the chain is closely related to the 

 facicd artery as that vessel is about to ascend over the base of the 

 mandible. They receive their afferent vessels from the following 

 sources ; 



1. The side of the nose. 7. The subjacent portion of the 



2. A few from the lower eyelid. floor of the mouth. 



3. The lower part of the cheek. 8. Half of the upper gum. 



4. Half of the upper lip. 9. The lateral part of the lower 



5. The lateral part of the lower gum. 



lip. 10. The superficial facial glands. 



6. The anterior third of the lat- 11. The submaxillary and sub- 



eral border of the tongue. Ungual saUvary glands. 



Their efferent vessels pass to those glands of the internal group of 

 the substemo-mastoid glands which are on a level with the upper 

 border of the th3Toid cartilage of the larynx. 



The suprahyoid or submental glands are situated beneath the 

 chin in the submental triangle, and are two or three in nvunber. 

 They receive their afferent lymphatics from the tip of the tongue, 

 the front of the floor of the mouth, and the inner part of the lower 



