338 



SPECIAL ANATOMY. 



Anonyma dextra. 

 Length : twelve to fourteen 

 lines. Course: vertically down- 

 wards and inwards. Pos. : pa- 

 rallel with art. anonyma, which 

 is close to it on the left; one 

 inch from the middle line ; to 

 the right and behind N. phreni- 

 cus and art. mammar. dextra. 

 Branches : Vv. mammaria in- 

 ter na and thyreoid. infer, dex- 

 tra ; often the v. vertebralis alone. 



Anonyma sinistra. 

 Longer (two inches) and 

 thicker. Course: almost horizon- 

 tal, backwards concave. Pos. : 

 above arcus aortce, behind the 

 superior border of the Sternum, 

 before art. anon., carol., and 

 subclavia sinistra. Branches : 

 Vv. mammar. interna, thyreoi- 

 dea sinistra, and phrenica su- 

 per., thymica, pericardiaca, and 

 often v. intercostalis superior 

 and v. vertebralis. 



The collateral branches : 



1. Vv. thyreoidea inferiores, one dextra, one sinistra. Course : like art. 

 thyr. infima; the former opens in the angle between the two Vv. anony- 

 mcB, the latter into the left v. anonyma; they receive Vv. tracheales and 

 laryng. (plexus trachealis). 



2. Vv. mammaricB internes, two for each artery ; they receive Vv. sternales 

 (plexus sternalis). 



3. Vv. phrenictB, very long and small ; they pass with N. phrenic, and art. 

 phren. super. 



4. V. vertebralis. Origin: in the deep cervical muscles, and a smaller 

 branch from the foram. condyloid. Course : in the canal, vertebralis, 

 passes out under the sixth or seventh vertebra, and opens close behind V. 



jugul. intern.; receives V. cervical, ascend, and profund. Position: be- 

 hind art. subclavia. 



592. 1. Jugularis interna, the internal jugular vein, corresponds to the 

 carotis communis and externa. Or. : in the foram. jugulare with a sacciform 

 enlargement, bulbus, passing out of the sinus transversus of the cranial cavity. 

 Course : descends at first behind, then on the outer side of carotis interna, 

 communis, and IV. vagus (which lies in a sheath between the artery and vein 

 behind them), and terminates, with an oval enlargement, bulbus, at the origin 

 of truncus anonymus before Art . subclavia. From foram. jugular, to the su- 

 perior border of the larynx, called cephalica interna, two inches and a half to 

 three inches long ; it is covered by m. digastricus and sterno'tnastoid, on the 

 outer side of the nn. glossophar., hypogloss., and pharynx, on the inner of the 

 proc. styloid., before proc. transvers. of the first to the third vertebra. At the 

 larynx it receives the short cephalica externa, which arises from the junction of 

 facialis anterior and posterior. 



a. V. facialis anterior corresponds to art. maxillar. externa. Course : ex- 

 ternal and behind art. maxillar. extern., downwards and outwards from 

 the internal angle of the eye, to the anterior border of m. masseter over 



