EXTERNAL THORACIC BRANCHES. 379 



subclavian artery outside the sealenus anticus muscle ; 3, first part of the axillary artery 

 giving rise to the acromial thoracic, short thoracic, &c. ; 4, third part of the axillary artery 

 giving rise to the subscapular, circumflex, &c. ; 5, commencement of the brachial artery ; 

 6, transverse superficial cervical artery ; 6', placed on the sealenus anticus muscle, marks 

 the ascending superficial cervical branch ; 7, posterior scapular artery arising from the sub- 

 clavian artery behind the sealenus anticus muscle and separate from the thyroid axis ; 8, 

 acromial branches of the acromial thoracic ; 9, pectoral branches of the same; 10, long 

 thoracic artery outside the pectoralis minor muscle; +, posterior circumflex branch 

 of the axillary artery (the anterior circumflex is seen rising from the opposite side of the 

 same part of the axillary trunk) ; 11, subscapular artery passing between the subscapularis 

 and teres minor muscles to proceed to the lower angle and dorsum of the scapula ; 12, 

 thoracic descending branch of the subscapular artery. Carotid Artery and its Brandies. 

 13, lower part, and 14, upper part of the right common carotid artery ; 15, trunk of the 

 external carotid artery brought fully into view by the removal of the digastric muscle ; 

 16, trunk of the internal carotid artery; 17, 17, the thyroid axis of the subclavian 

 artery, and the inferior thyroid artery where it is distributed in the gland ; 18, superior 

 thyroid artery anastomosing in the gland with the inferior thyroid ; 19, lingual artery 

 brought into view by the removal of the lower part of the hyoglossus muscle ; 20, facial 

 artery giving off the palatine, tonsillar, and submental ; 21, inferior labial ; 22, coronary 

 artery ; 23, occipital artery ; 24, posterior auricular artery ; 25, superficial temporal 

 artery ; 26, internal maxillary artery ; 27, transverse facial, given off in this instance 

 directly by the external carotid artery. 



branch to the shoulder, and the anterior and posterior circumflex branches 

 to the upper part of the arm. The branches are not constant in their 

 number, size, or mode of origin. 



EXTERNAL THORACIC BRANCHES. These branches vary much in number; 

 but, after the method of Haller, four are usually described. 



1. The superior thoracic artery (thoracica suprema), a branch of incon- 

 siderable size, arises at a point internal to the pectoralis minor muscle, and 

 inclines dowriwards and inwards across the first two intercostal spaces, 

 anastomosing with the internal mammary and intercostal branches contained 

 in them, and terminates between the pectoral muscles. 



2. The acromial thoracic artery (art. thoracica humeraria), of considerable 

 size, and by far the most constant of the thoracic branches of the axillary, 

 arises from its forepart at the inner border of the pectoralis minor muscle, 

 and soon divides into branches which take different directions. 



(a) The acromial branches pass partly to the deltoid muscle and partly to the 

 upper surface of the acromion, and anastomose with the suprascapular and posterior 

 circumflex arteries. 



(b) The humeral branch passes down in the interval between the pectoralis major 

 and deltoid muscles, accompanying the cephalic vein. 



(c) The thoracic branches are distributed to the serratus magnus and pectoral 

 muscles, and anastomose with the other thoracic arteries. 



(d) The clavicular branch, very small, passes inwards to the feubclavius muscle. 



3. The long thoracic or external mammary artery is directed downwards and 

 inwards, along the lower border of the pectoralis minor, and is distributed 

 to the mamma, and to the serratus and pectoral muscles, and anastomoses 

 with the external branches of the intercostal arteries. 



4. The alar thoracic branch is a very small vessel and not constant, 

 being frequently wanting, and having its place supplied by branches from the 

 thoracic and subscapular arteries. It is distributed to the lymphatic glands 

 and the fatty tissue in the axilla. 



SUBSCAPULAR ARTERY. This branch, the largest given off by the axillary 

 artery, arises close to the lower border of the subscapular muscle, along 

 which it proceeds downwards and backwards, towards the inferior angle of 

 the scapula, accompanied by the subscapular nerve ; and it terminates in 



c c 2 



