THE BEACHIAL Oli AXILLARY ARTEBIES. 



647 



4. Internal Thoracic (Pectoral), or Internal Mammary Artery 



(Fig. 375, 9). 



The internal thoracic artery emerges from the brachial trunk at the first rib, 



Fig. 375. 



DISTRIBUTION OF THE ANTERIOR AORT.\. 



I, Anterior torta; 2, left axillary arterv ; 3, right axillary artery; 4, dorsal artery; 5, subcostal 

 artery; 6, superior cervical artery; l\ vertebral artery; 8, 8', inferior cervical artery ; 9, origin 

 of the internal thoracic artery ; io, origin of one of the external or intercostal branches of this 

 artery; 11, one of its inferior ramuscules ; 12, external thoracic artery ; 13, origin of the supra- 

 scapular artery; 14, common carotid artery ; 14', accessory thyroid artery ; 14", thyro-laryngeal 

 artery; 15, atloido-muscular artery; 16,' occipito-muscular artery; 17, posterior aorta. A, 

 Pulmonary aorta; B, trachea; C, oesophagus; D, cervical ligament; E, superior branch of the 

 longissimus dorsi muscle ; P, inferior branch of the same ; G, complexus muscle ; H, splenius 

 muscle; i, J, originating aponeurosis of the splenius and the serratus anticus muscles; K, section 

 of the obliquus capitis major; L, rectus capitis posticus major; M, rectus capitis anticus major; 

 N, sterno-maxiUaris ; O, P, deep and superficial pectoral muscles turned downwards. 



