404 



x\rteries of the Arm. 



1. A. vertebralis (oontiimed) see Figs. 444 448): 

 BraiK'hes of the a. basilaris: 



f) J. cerebelli inferior anterior, paired, runs lateralward to the anterior part of the in- 



ferior surface of the cerebeUuiu. 



g) A. miditiva interna (0. T. internal auditory artery) goes lateralward to the nn. facialis 



and acusticus and with these into the meatus acusticus internus ; it supplies the in- 

 ternal ear by means of a delicate branch. 



h) Rami ad pontem (0. T. transverse 'or pontal arteries), numerous small branches, to 

 the substance of the pons. 



i) A. cerebelli superior, paired, arises shortly before the terminal subdivision, extends, at 

 the anterior margin of the pons, lateralward and backward, forms a loop around the 

 pedunculus cerebri so as to arrive upon the upper surface of the cerebellum and supplies 

 mainly this region; it gives oft' branches to the plexus chorioideus ventriculi tertii. 



t) A. cerebri posterior (posterior cerebral artery), paired, at first parallel to the preceding 

 artery, separated from it by the n. oculomotorius and further lateralward by the 

 tentorium cerebelli; it goes at the anterior margin of the pons around the pedunculus 

 cerebri to the inferior surface of the occipital lobe. It gives off branches through the 

 substantia perforata posterior to the cerebral ganglia, branches to the cerebral pen- 

 duncles and to the plexus chorioideus ventriculi lateralis and supplies the whole occipital 

 lobe and the temporal lobe with the exception of the gyrus temporaUs superior. 



The a. cerebri posterior receives near its origin the a. communicans posterior (from 

 the a. carotis interna) ; in this way arises the circidus arlrriosus / ff'illisij (0. T. circle 

 of Willis) which lies over the sella turcica and the diaphragma sellae and surrounds 

 the chiasma opticum, the tuber cinereum and the corpora niamillaria. 



2. Truiicus thyreocervicalis(O.T. thethjToid axis) (seealsoFig. 434), arises from the an- 

 terior wall of the a. subclavia : it divides in a somewhat variable manner into the following branches : 



a) A. thyreoidea inferior, runs, in front of the m. scalenus anterior, at first upward and 

 then bends behind the a. carotis communis medianward and forward to the posterior 

 surface of the glandula thyreoidea, into which it penetrates by means of its rami rjlan- 

 dulares- it gives oft' on its way the rami phari/uf/ei, oesop/iar/ei tracheules, as 

 well as the a. larynr/ca inferior (see Fig. 435), which goes below the ni. crico- 

 phar\Tigeus into the larynx and anastomoses iipon the lateral surface of the internal 

 laryngeal muscles with the a. laryngea superior (from the a. thyreoidea superior). 



Vj A. cervicalis ascendens, ascends upon the origins of the mm. scaleni and levator scapulae, 

 at first medianward from the n. phrenicus, behind the v. jugularis interna often going 

 as far upward as the base of the skull ; it gives off below several rami spinules into 

 the foramina intervertebralia as well as J-ami musculares to the surrounding muscles ; 

 one of the latter branches, ramus profundus (see also Fig. 441), runs between the 

 transverse processes of the 4tli and o^^ cervical vertebra backward to the deep mus- 

 cles of the neck; it can take the place of the a. cervicalis profunda. 



c) A. cervicalis super fcialis, goes behind the m. omohyoideus transversely through the 



fossa supraclavicularis major, in front of the mm. scaleni, levator scapulae and plexus 

 brachialis, becomes hidden beneatli the m. trapezius and supplies this and adjacent muscles. 



d) A. transversa scapulae (0. T. suprascapular or transversalis humeri) (see also Fig. 452), 



bends downward and forward, in front of the m. scalenus anterior, to the posterior 



surface of the clavicle and runs along this bone over the lig. transversum scapulae 



superius to the fossa supraspinata; it then runs behind the coUum scapulae in front 



of the lig. transversum scapulae inferius to the fossa infraspinata, and there forms a 



broad anastomosis with the a. cireumflexa scapulae. Near the incisura scapulae arises 



the ramus acro7nialis, which goes through the m. trapezius to the rete acromiale. 



3. A. mammaria interna (internal mammary artery) (see also Fig. 450) goes from 



the inferior wall of the a. subclavia medianward and downward behind the v. subclavia directly 



upon the pleura and then vertically downward just behind the cartilages of the V^ T'h rib. 



It runs nearly parallel to the lateral margin of the sternum , is s(>parated from it, increasing 



from above downward, one to two cm. and is covered behind by the pleura and by the 



m. transversus thoracis. In the region of the ett intercostal space it divides into its two 



terminal branches: a. musculoplircnica and a. epir/aslrica superior. Branches: 



a) Aa. jnediastinales anleriores, delicate branches, backward to the structures lying in 



the spatiura mediastinale anterius. 



b) Aa. thijmkae (not ilhistratiMi), partly from neighboring vessels, backward to the thymus. 



c) Rami broncldales (not illustrated), " to the lower end of the trachea and the bronchi; 



often absent. 



d) A. pericardiacophrenica, with the n. phrenicus in front of the root of the lung on th(> 



pericardium downward to the diaphragm; it supplies the pericardium and the diaphragm. 



