THE NECK 



1361 



(6) Below the hyoid bone. — The importance of the fascia here is infinitely 

 greater. Four layers must be remembered; (i) Superficial; (ii) pretracheal; 

 (iii) prevertebral ; (iv) carotid, (i) Superficial. This starts from the ligamentum 

 nuchse, encases the trapezius, forms the roof of the posterior triangle where it is 

 perforated b}^ branches of the superficial cervical nerves and the external jugular 



Fig. 1102. — The Collateral Circulation after Ligature of the Common Carotid and 



Subclavian Arteries. 

 (A ligature is placed on the common carotid and on the third portion of the subclavian artery.) 



Kight anterior cerebral 



Internal carotid- 

 Right posterior cerebral ■ 



Occipital 

 Descending branch of occipital 



External carotid 



Superficial branch of descending 



occipital 



Deep branch 



Transverse 



cervical 



Descending branch 



Acromical branch 



Subscapular branch 



Supraspinous 

 branch 



Anterior circumflex 



Infraspinous 



branch 



Post. 



circumflex - .^^ 



Lateral thoracic '' ^s?^ 



Subscapular 



Circumflex 



scapular 



Inf rascapular 



Subscapular 



Left anterior cerebral 

 Anterior communicating 



Post, communicating 

 Left posterior cerebral 



Basilar 



Anterior spinal 



Vertebral 



External maxillary 

 Lingual 



Superior thjreoid 



Inferior thyreoid 

 Common carotid 



Thyreo-cervical trunk 

 Superior intercostal 



Innominate 

 Superior 

 intercostal 

 Left com. carotid 



Left subclavian 

 Sup. thoracic 

 Internal mammary 



Anterior intercostal 



First aortic 

 intercostal 



Second aortic 

 intercostal 



Anterior 

 intercostal 



Third aortic 

 intercostal 



vein. Passing on it encloses the sterno-mastoid; and, passing over the anterior 

 triangle, itjmeets its fellow in the middle line. 



Thin behind, it is thickened anteriorly. Behind this thickened union lie the anterior 

 jugular veins. Below, at a varying distance below the thyreoid cartilage, this layer divides 

 into two, attached to the front and back of the manubrium. Between these (Burns's space) 



86 



