1 42 APPLIED ANATOMY. 



blood through the jugular vein. Running down on the anterior surface of the 

 artery is the descendens hypoglossi nerve. If seen it should be pushed aside. It 

 supplies the sternohyoid, sternothyroid, and both bellies of the omohyoid muscles. 

 The pneumogastric nerve lies posteriorly, between the artery and the vein. Care 

 will be necessary to avoid including it in the ligature. The ligature is to be carried from 

 the outer to the inner side, the needle being passed between the vein and the artery. 

 Ligation of the Common Carotid Artery Below the Omohyoid Muscle. The artery 

 below the omohyoid muscle becomes deeper and less accessible. The sternohyoid 

 muscle overlaps it and is less easily displaced. The sternohyoid and sternothyroid 

 muscles likewise tend to encroach on it and have to be drawn inward. The internal 

 jugular vein and carotid artery diverge as they descend, so that at the level of the 

 sternoclavicular joint they are separated 2.5 cm. In this interval the first portion 

 of the subclavian artery shows itself. The anterior jugular vein will probably be 

 encountered along the edge of the sternomastoid muscle, and near the omohyoid 



Sternomastoid artery 

 Common carotid artery 

 Descendens hypoglossi nerve 

 Internal jugular vein 

 Sternomastoid muscle 

 Omohyoid muscle 



FIG. 171. Ligation of the common carotid artery. 



muscle the artery will be crossed by the middle thyroid vein. Still lower it may be 

 that the inferior thyroid will be encountered. Posterior to the carotid artery is the 

 inferior thyroid artery, coming from the thyroid axis and going to the thyroid gland, 

 and winding around from posteriorly to the inner side is the recurrent laryngeal 

 nerve. The ligating needle is to be passed from without inward. 



Collateral Circulation After Ligation of the Common Carotid Artery. When 

 the common carotid has been tied the blood reaches the parts beyond from the 

 branches of the carotid of the opposite side and from the subclavian artery of the 

 same side. The branches of the external carotid anastomose across the median line. 

 This is particularly the case with the superior thyroid and facial. The internal 

 carotids communicate by means of the circle of Willis. From the subclavian the 

 vertebral artery communicates by means of the basilar with the circle of Willis. 

 The thyroid axis by its inferior thyroid branch communicates with the thyroid 

 arteries of the opposite side. An ascending branch of the inferior thyroid as well as 

 one from the transverse cervical, also from the thyroid axis, anastomose with 

 branches of the princeps cervicis, which is a descending branch of the occipital. 



