226 THE VASCULAR SYSTEM. 



reached at the ciliary processes. In its course the artery sup- 

 plies : 



a. Muscular branches, given off at the point where the artery 

 reaches the eyeball. 



ft. Two arteries (AA. ciliares) to the choroid, given off at the 

 same point as the foregoing. 



y. Two arteries to the iris. 



8. The Art. hyaloid ea, the terminal portion of the ophthalmic- 

 artery. (For further description of these vessels, see Eye.)]. 



2. The systemic arch (Duclns aorticus), (Figs. 132, 143, and 

 145 II] is the middle arch of the three; it arises from the middle 

 canal of the Ductns arteriosus, and winds obliquely round the 

 oesophagus between the MM. petrokyoidei /^and II towards the 

 vertebral column, which it reaches at about the level of the 

 sixth vertebra. The right systemic arch is continued as the 

 dorsal aorta, the left arch communicates with it merely by a 

 small opening,, and is then continued as the coeliaco-mesenteric 

 artery. 



Branches of the systemic arch : 



a. The laryngeal artery (Arteria laryngea), (Fig. 146 fg) arises 

 from the inner border of the systemic arch before it reaches the 

 oesophagus ; it passes forwards and inwards to be distributed in 

 the larynx and pharynx. According to Briicke this artery possesses 

 a valve at its point of origin. 



p. 6 b. The oesophageal arteries (Arteriae 



oesophageae] pass from the upper part of the 

 arch to the dorsal surface of the oesophagus. 

 c. The occipito- vertebral artery (Ecker), 

 (Art. occipito-vertebralis], (Fig. 147 o,v] [arises 

 from the systemic arch immediately in 

 front of the transverse process of the second 

 vertebra, and ascends immediately in contact 

 Transverse (section at level of with t^ e body of the first vertebra, which it 

 the larynx. separates from the MM. intertmnsversarii 



G Carotid gland. capitis and the sympathetic cordl. Immedi- 



G Glottis. f. , , ! 



ig Laryngeal artery. ately under the most anterior portion or the 



? cSSSbf^' M - fongissimus dorsi the artery divides into 

 IT Aortic arch. two branches, the vertebral and occipital 



arteries : 

 (i) The vertebral artery (Arteria vertebralis or supra-vertebrali* 



