THE VEINK OF THE DIPLOE. 599 



The middle thyroid vein collects the blood from the lower part of the lateral 

 lobe of the thyroid gland, and, being joined by some veins from the larynx and 

 trachea, terminates in the lower part of the internal jugular vein. 



The facial and occipital veins have been described above. 



Surgical Anatomy. The internal jugular vein occasionally requires ligature in cases of 

 septic thrombosis of the lateral sinus from suppuration in the middle ear, in order to prevent 

 septic eiuboli being carried into the general circulation. This operation has been performed 

 recently in several cases, with the most satisfactory results. The cases are generally those of 

 chronic disease of the middle ear, with discharge of pus which perhaps has existed for many 

 yqars. The patient is seized with acute septic inflammation, spreading to the mastoid cells, 

 and consequent on this, septic thrombosis of the lateral sinus extending to the internal jugular 

 vein. Such cases are always extremely grave, for there is a danger of a portion of the septic 

 clot being detached and causing septic embolism in the thoracic viscera. If the condition is 

 suspected, the sinus should be at once explored by trephining at a point an inch behind the 

 centre of the external auditory meatus and a quarter of an inch above Reid's base line. The 

 condition of the sinus is then investigated, and if it is found to be thrombosed, the surgeon 

 should at once proceed to ligate the internal jugular vein, by an incision along the anterior 

 border of the sterno-mastoid, the centre of which is on a level with the greater cornu of the 

 hyoid bone. The vein should be ligated in two places and divided between. After the vessel 

 has been secured and divided, the lateral sinus is to be thoroughly cleared out, and by removing 

 the ligature from the upper end of the divided vein, all septic clots removed by syringing from 

 the sinus through the vein. If hemorrhage occurs from the distal end of the sinus, it can be 

 arrested by careful plugging with antiseptic gauze. 



The Vertebral Vein commences in the occipital region by numerous small 

 tributaries from the deep muscles at the upper and back part of the neck ; these 

 pass outward and enter the foramen in the transverse process of the atlas, and 

 descend, forming a dense plexus around the vertebral artery in the canal formed 

 by the foramina in the transverse processes of the cervical vertebrae. This 

 plexus unites at the lower part of the neck into two main trunks, one of which 

 emerges from the foramen in the transverse .process of the sixth cervical vertebra, 

 and the other through that of the seventh, and, uniting, form a single vessel, 

 which terminates at the root of the neck in the back part of the innominate vein 

 near its origin, its mouth being guarded by a pair of valves. On the right side 

 it crosses the first part of the subclavian artery. 



Tributaries. The vertebral vein receives in its course a vein from the inside 

 of the skull through the posterior condyloid foramen ; muscular veins from the 

 muscles in the prevertebral region ; dorsi-spinal veins, from the back part of the 

 cervical portion of the spine ; meningo-rachidian veins, from the interior of the 

 spinal canal ; the anterior and posterior vertebral veins ; and close to its termina- 

 tion it is joined by a small vein from the first intercostal space which accompanies 

 the superior intercostal artery. 



The anterior vertebral vein commences in a plexus around the transverse pro- 

 cesses of the upper cervical vertebrae, descends in company with the ascending 

 cervical artery between the Scalenus anticus and Rectus capitis anticus major 

 muscles, and opens into the vertebral vein just before its termination. 



The posterior vertebral vein (the deep cervical) accompanies the profunda cer- 

 vicis artery, lying between the Complexus and Semispinalis colli. It commences 

 in the suboccipital region by communicating branches from the occipital vein and 

 tributaries from the deep muscles at the back of the neck. It receives tribu- 

 taries from the plexuses around the spinous processes of the cervical vertebras, an 

 terminates in the lower end of the vertebral vein. 



The Veins of the Diploe. 



The diploe of the cranial bones is channelled in the adult by a number of 

 tortuous canals, which are lined by a more or less complete layer of compact 

 tissue. , . i 



The veins they contain are large and capacious, their walls being 

 formed only of endothelium resting upon a layer of elastic tissue, and they pr< 

 scut at irregular intervals pouch-like dilatations, or culs-de-mc, which s 



