Branches of Thyroid Axis 233 



condylar foramen, and it gathers many branches from the spinal cord 

 and column, and from the muscles of the neck. 



The thyroid axis comes from the front of the first part of the artery, 

 and at once breaks into the inferior thyroid, and supra- and posterior 

 scapular branches I- 

 The inferior thyroid, in order to reach the thyroid body, winds 

 beneath the sheath of the common carotid and the middle sympathetic 

 ganglion, at the level at which the omo-hyoid crosses the front of the 

 sheath opposite the fifth cervical vertebra. 



Ligation. Sometimes this artery is tied in the case of enlargement 

 of the thyroid gland. An incision of 2 or 3 in. is made in front of the 

 lower part of the sterno-mastoid, and the vessel is then sought opposite 

 the cricoid cartilage. 



Branches. Unimportant twigs are given to the muscles in its 

 neighbourhood. 



The ascending- cervical runs in the groove between the scalenus 

 anticus and the rectus anticus major, giving twigs to those muscles, and 

 others to anastomose with the vertebral in the spinal canal. Tracheal, 

 cesophageal, and laryngeal branches also pass off. 



The termination of the inferior thyroid anastomoses with its fellow 

 of the opposite side, and with the superior thyroid artery in the lower 

 part of the thyroid body. 



The supra-scapular artery passes outwards in front of the 

 scalenus anticus and phrenic nerve, and behind the clavicular origin 

 of the sterno-mastoid. And, as the supra-scapular notch is below the 

 level of the clavicle, the artery sinks behind the clavicle, where it lies 

 in front of the third part of the subclavian artery, and gives twigs 

 to the sterno-mastoid and subclavius. Then, winding on above the 

 ligament, it ramifies beneath the supra- and infra-spinatus muscles, 

 supplying the shoulder-joint, and anastomosing with the posterior and 

 the dorsal scapular (v. p. 231) arteries. 



It sends a twig through the trapezius, on to the acromion process, 

 which anastomoses with the acromial thoracic. 



The posterior scapular, in order to reach the vertebral border of 

 the shoulder-blade, runs across the root of the neck ; this course gives 

 it the alternative name of transversalis colli. The artery passes over 

 the phrenic and the scalenus anticus, and lies in the subclavian 

 triangle, but at a higher level than the.supra-scapular artery. It leaves 

 the triangle beneath the omo-hyoid, passing over the brachial plexus, 

 and reaches the anterior border of the trapezius, where it gives off the 

 superficial cervical branch, which anastomoses with the superficial 

 part of the princeps cervicis of the occipital (p. 30). 



The continuation of the artery then descends along the border of 

 the shoulder-blade, beneath the levator anguli scapulae and the 

 rhomboids, anastomosing with the supra- and subscapular arteries, and, 

 in the neighbourhood of the rhomboids, with the posterior intercostal. 



