Veins of the Head and Neck. 445 



Yeiiae diploioae (see Fig. 485) are thin-walled tubes, which lie in the fiat canales 

 diploid [Brescheti] in the substance of the bones of the roof of the skuU. They have no 

 valves ; they are arranged in the form of a network and are very variable. The main stems run 

 from above downward and are connected at their extremities by openings (emissaria) with the 

 external veins of the skull or with the sinus durae matris or (usually) with both at tlie same time. 



1) V. diploica frontalis opens into the v. supraorbitalis and the sinus sagittalis superior. 



2) V . diploica temjioralis anterior mio a v. temporalis profunda and the sinus sphonoparietahs. 



3) V. dijiloica temporalis posterior (0. T. external parietal or posterior temporal diploic 



vein) extends from the emissarium parietale to the emissarium mastoideimi. 



4) V. diploica occipitalis opens into the emissarium occipitale. 



Emissarium jmrietale, in the foramen parietale, unites the sinus sagittalis superior with 

 the superficial veins of the skull; its valves permit a flow in an outward direction only. 



Emissarium. masioidevm, in the foramen raastoideum, unites the sinus transversus with 

 the V. auricularis posterior or with the v. occipitalis or with the beginning of the v. jugularis externa. 



Emissarium occipitale, at the level of the protuberantiae occipitales, opens usually either 

 internally into a sinus transversus or into the confluens sinuimi or externally into the v. oc- 

 cipitalis, often into both. 



Emissarium condyloideum (not illustrated), in the canalis condyloideus, unites the sinus 

 transversus and the plexus venosi vertebrales externi. 



Plexus Yeuosus caroticiis internus (see Fig. 442) surrounds the a. carotis interna 

 in the canalis caroticus in the form of a network, is connected above with the sinus caveniosus, 

 receives veins from the cavum tympani and opens below into the v. jugularis interna. 



Rete foramiuis ovalis (not illustrated) in the foramen ovale from the sinus cavemosus 

 to the plexus pterygoideus : it is often connected above with the vv. raeningeae mediae. 



"Rete canalis hypoglossi (not illustrated) in the canalis hypogiossi from the sinus 

 occipitalis and from the plexus venosi vertebrales intemi to the sinus petrosus inferior. 



Yena cava superior (see Figs. 411, 427, 486 and 495), impaired, free from valves, 

 arises behind the first right costal cartilage by the union of the YV. auonymae dextra et 

 sinistra and extends downward, and curved moderately convex toward the right, in fi-ont 

 of the root of the right lung and of the right side of the aorta ascendens, to the right atrium. 

 It is bounded in front by the thymus and on the right by the right lung; it is covered above 

 on its right side by the pleura mediastinalis, below by the visceral layer of the pericardium. In 

 the upper part of its course the v. azygos (see p. 456) opens into it from behind. 



y. ailOliyma (0. T. innominate vein) (see also Figs. 427, 486 and 495) is formed 

 behind the articulatio sternoclavicularis and in front of the a. subclavia by the union of the 

 V. jugularis interna, v. subclavia and y. jugularis externa 5 the latter opens usually 

 into the v. subclavia. The right vein is bounded on the right by the right lung and runs 

 vertically downward ; the left, distinctly longer, extends to the right and downward, behind the 

 manubrium sterni and the thymus, directly over the arcus aortae, in front of the aa. subclavia 

 sinistra, carotis communis sinistra and anonyma. Both veins are devoid of valves. Branches : 



\. Vy. thyreoideae inferiores (inferior thyreoid veins) (see Fig. 486) from the plexus 

 thyreoideus impar. This lies partly in front of the lower margin of the isthmus glandulae 

 thyreoideae, in part it surrounds the beginning of the trachea like a ring ; it anastomoses with 

 the vv. thyreoideae superiores of both sides and receives, behind, the vv. tracheales, the 

 vv. oesophageae and the v. laryngea inferior (corresponding to the arteries of the same names). 

 Three veins usually go off from the plexus: a right vein opens at the angle of junction of the 

 w. anonymae or into the v. anonyma dextra or into the v. jugularis interna dextra, a left vein 

 into the V. anonj-ma sinistra and a v. thyreoidea ima, running downward in front of the 

 trachea, into tlie v. anonyma sinistra. 



2. V. mammaria interna (internal mammary vein) (see Figs. 313 and 486) con-esponds 

 almost exactly to the artery of the same name. Arismg from the union of the 2 vv. epi- 

 gastricae stiperiores (rich in valves) and the vv. mtisculophrenicae it is double in the region 

 of the m. transversus thoracis; above the latter it is single and situated medial from the artery. 

 It receives (with the vv. musculophrenicae) the anterior extremities of the 9 ( 10) superior 

 vv. intei-costalcs (see p. 455), which have valves at their mouths, further the rami perforantes, 

 which have valves (especially marked in the l^t or 2nd intercostal space), as well as rami 

 sternales from the networks which are situated upon both surfaces of the sternum, and in 

 which there are several large transverse connections between the trunks of the two sides, 

 sometimes especially one such on the anterior surface of the processus xiphoideus. 



3. Yv. phrenicae superiores (not illustrated), possess valves, are double, and con-e- 

 spond to the a. pericardiacophrenica. 



4. Yy. thymicae, pericardiaeae, niediastinales anteriores, bronchiales anteriores 

 (not illustrated) from the viscera of the thorax, open separately or partially in cummon. 



Spalteholz, Atlas. 29 



