86 EQUINE ANATOMY. 



It gives off the sub-costal, which sends branches to the second, 

 third and fourth intercostal spaces. 



2. Superior or deep cervical. 



Passes between first two ribs to muscles of neck or back, to 

 spinal cord and first intercostal space. 



3. Vertebral. 



Through foramina of the upper six cervical vertebrae, anasto- 

 mosing with the occipital, and giving off muscular and spinal 

 branches, called superior, inferior, external and internal. 



4. Internal thoracic or internal mammary. 



Given off near the first rib; runs above the costal cartilages to 

 the xiphoid appendix. 



Branches. 



Superior to pericardium and mediastinum; inferior to pectoral 

 muscles, external or intercostal; anterior abdominal passes into 

 rectus muscle and anastomoses with post-abdominal. 



Asternal artery to thirteenth intercostal space, anastomosing 

 with artery; gives off abdominal, intercostal and diaphragmatic 

 branches. 



5. External thoracic or external mammary. 



Given off in front of preceding, curving around first rib; sup- 

 plies pectoral and other muscles of chest. 



6. Inferior cervical. 



Given off opposite the two preceding; divides into two branches, 

 superior (ascending cervical)' to muscles and glands of neck, 

 and inferior (acromio-thoracic) to pectoral muscles. 



7. Superior scapular. 



Given off near sub-scapular tendon; passes up and terminates 

 in scapular muscles and shoulder joint. 



8. Sub-scapular. 



Given off at junction of axillary portion with humeral artery; 

 passes up and backward near the dorsal angle of scapula. 



Branches. 



One to latissimus dor si. 



Muscular branches to scapular muscles. 



Scapulo-humeral to muscles of shoulder and arm. 



HUMERAL ARTERY. 



From posterior border of sub-scapularis muscle to above in- 



