THE VESSELS. 309 



1. Art. sacci lacrymalis to the mucous membrane of the lacrymal sac, into 



2. Angularis, which passes between m. pyramidalis nasi and levat. Idbii 

 sup., and anastomoses with the maxillar. externa. (See that artery.) 



3. Dorsalis nasi, passes upon the back of the nose under the skin trans- 

 versely below the forehead, extends downwards, often to the middle of 

 the nose, and anastomoses on the nasal pinna with Art. alaris nasi. 



i. Frontalis, the terminal branch of ophthalmica, smaller than h, passes 

 parallel with A. supraorbitalis upwards to the forehead, where it divides into 

 branches for the skin, the muscles, and the periosteum, and anastomoses with 

 art. temporalis. 



552. 2. Art. cerebri anterior a. corporis callosi, passes away above n. 

 opticus, behind the root of olfactorius, (forwards) and inwards towards the 

 middle line, and in the fissure between the two anterior cerebral lobes on the 

 inferior surface of the brain; here, a stronger, short (two lines) transverse 

 branch unites the two anterior cerebral arteries, ram. communicans anterior. 

 Each artery then turns round the anterior border of corp. callosum, passes upon 

 its superior surface to the posterior border, and terminates with a small branch 

 curved upwards in the neighbouring convolutions. Branches : to nn. opticus, 

 olfactorius, to ventriculus tertius, to the inferior and internal surface of the an- 

 terior cerebral lobes, to corp. callosum. 



3. Art. cerebri media s. fosses Sylvii passes externally and internally into 

 fossa Sylvii, divides into three branches for the anterior and middle cerebral 

 lobes, and anastomoses with Art. cerebri anterior and posterior. Small 

 branches pass directly from below upwards to the corp. striatum. Is larger 

 than 2. and 4. 



4. Art. s. ramus communicans (posterior), arises from the posterior part of 

 carotis intern. ; passes under tractus n. optic, backwards (one half to three 

 quarters of an inch long), and forms with art. cerebri posterior (s. Art. verte- 

 bralis) the circulus arteriosus Willisii. 



5. Art. choroidea arises above the former, passes outwards and backwards 

 with the tractus n. opticor. below the crus cerebri, enters into the lateral ven- 

 tricle, on the cornu ammonis around the thalamus, and ramifies in the vascular 

 plexus, plexus choroideus of the third [lateral] ventricle. 



All the arteries of the brain take a very tortuous course. 



553. B. Subclavia, the subclavian artery. 



Origin : the right from the truncus anonymus ; the left from 

 the arcus aorta. (The right frequently arises below the left, at 

 the posterior inferior part of the arcus aortcs, and betakes itself to 

 the right behind trachea and cesophagus, sometimes between the 

 two). Course : ascends as high as the apex of the lungs, curves 

 over the first rib, and passes between scalenus anticus and medius, 

 outwards and downwards to the axillary cavity. The right i 

 shorter, thicker, and inclines less upwards than outwards. Situa 

 tion : first portion, from the origin to m. scalenus anticus. 



