tl36 A MANUAL OF ANATOMY 



extremity comes into contact with its fellow of the opposite side 

 over the anterior border of the genio-hyo-glossus muscle. 



The sublingual ducts vary in number from ten to twenty, and are 

 known as the ducts of Walther (ducts of Rivini). A few of them 

 open into Wharton's duct, but the majority open in a linear manner 

 upon the summit of the plica sublingualis. One of the ducts, called 

 the duct of Bartholin, or great duct of Rivini, issues from the 

 external lobule of the gland, and, accompanying Wharton's duct, 

 it opens quite close to the orifice of that duct. 



Blood-supply. — ^The gland derives its blood from the sublingual 

 branch of the lingual, and the subment£il branch of the facial, 

 arteries. 



Nerve-supply. — ^The nerves are derived from the chorda tympani 

 and lingual nerves, and the sympathetic plexus on the facial artery, 

 through means of a branch of the submaxillary ganglion, which is 

 conducted to the sublingual gland by the lingual nerve. 



Structure. — The sublingual gland is a mucous gland, and its general struc- 

 ture is similar to that of the parotid and submaxillary glands, but the lobules 

 are more loosely arranged. The cells of the sublingual alveoli are for the most 

 part mucous cells, but there are also serous or albuminous cells. 



Development. — The sublingual gland is developed as a solid outgrowth of 

 the buccal epithelium. This outgrowth undergoes ramifications, and these 

 subsequently become hollow. 



Scalene Muscles and Subclavian Artery. 



Scalene Muscles. — The scalene muscles are three in number, 

 namely, scalenus anticus, scalenus medius, and scalenus posticus. 



Scalenus Anticus — Origin. — By four short tapering tendons from 

 the tubercles of the costal processes (anterior tubercles of the 

 transverse processes) of the third, fourth, fifth, and sixth cervical 

 vertebrae. 



Insertion. — ^The scalene tubercle of the first rib. 



Nerve-supply. — ^The anterior primary divisions of the fourth, 

 fifth, and sixth cervical nerves. 



The muscle is directed downwards, outwards, and forwards. 



Action. — (i) To fix the first rib in ordinary inspiration, and to 

 elevate it in forced inspiration ; and (2) to flex the neck to one side 

 and slightly forwards. 



Chief Relations — Anterior. — ^The phrenic nerve, which crosses the 

 muscle obliquely downwards and inwards ; the internal jugular 

 vein, which lies over its origin ; and the subclavian vein close to its 

 insertion. Posterior. — The scalenus medius, with the intervention 

 of the second part of the subclavian artery, the nerve-roots of the 

 brachial plexus, and the dome of the pleura. Internal. — ^The 

 ascending cervical artery, and the origin of the rectus capitis anticus 

 major. 



Scalenus Medius — Origin. — By six short tapering tendons from 

 the tubercles of the transverse processes (posterior tubercles) of the 

 lower six cervical vertebrae. 



