VEINS OF THE DIPLOfi. 



48£ 



according to the arterial branches which they accompany, join to form 

 a short single trunk, which leaves the orbit by the inner part of the 

 sphenoidal fissure, where it is placed between the heads of the external 

 rectus muscle, and terminates in the cavernous sinus. 



Varieties. — Not unfrcquently one of the frontal veins is much larger than 

 the others, and descending vertically near the middle of the forehead, joins the 

 facial and a branch of the ophthalmic vein on one side of the root of the nose. 



VEINS OF THE X)IPLOE. 



The veins of the diploe of the cranial bones are only to be seen 

 after the pericranium is detached, and the external table of the skull 

 carefully removed by means of a file. Lodged in canals hollowed in 

 the substance of the bones, their branches form an irregular network, 

 from which a few larger vessels issue. These are directed downwards 

 at different parts of the cranium, and terminate, partly in the veins on 

 the outer surface of the bones, and partly in the sinuses at the base of 

 the skull. 



Fig. 309.— Veins op Fig. 309. 



THE Diploe of the 

 Cranial Boxes (after 

 Breschet). ^ 



The external table has 

 been removed from the 

 greater part of the cal- 

 varium so as to expose 

 the diploe and the veins 

 which have been in- 

 jected. 1, a single 

 frontal vein ; 2, 3, the 

 anterior temporal vein 

 of the right side ; 4, 

 the posterior temporal ; 

 f», the occipital vein of 

 the diploe. 



According to Bres- 

 chet there are four 

 such veins on each 

 half of the cranium, 

 viz., a frontal, an occipital, and two temporal. 



The frontal is small, and issues by an aperture at the supra-orbital notch to 

 join the vein in that situation. There is often only one frontal vein present. 



The temporal are distinguished as anterior and posterior. The anterior is con- 

 tained chiefly in the frontal bone, bub may extend also into the parietal, and opens 

 into the temporal vein, after escaping by an aperture in the great -wing of the 

 sphenoid. The posterior ramifies in the parietal bone, and jsasses through an 

 aperture at the lower and hinder angle of that bone to the lateral sinus. 



The occipital is the largest of all ; and leaves the occipital bone opposite the 

 inferior ciu-ved line to open, either internally or externally, into the occipital 

 sinus or the occipital vein. Its ramifications are confined especially to the occi- 

 pital bone. 



VEINS OF THE UPPER LIMB. 



The veins of the upper limb are divisible into two sets, the super- 

 ficial, and the deep-seated. Both sets are provided with valves, and 



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