IO6 AX ATOMY AND PHYSIOLOGY FOR NURSES 



The vertebral artery is the first and largest branch. It 

 arises from the back part of the subclavian artery, passes 

 upward through the foramina in the transverse process of 

 the upper six cervical vertebrae ; it turns backward around 

 the articulating process of the atlas, after which it enters 

 the skull through the foramen magnum. The two ver- 

 tebral arteries unite to form the basilar artery. The 

 branches of the vertebral may be divided into two groups : 



Cervical branches. Cranial branches. 



Lateral spinal. Posterior meningeal. 



Muscular. Anterior spinal. 



Posterior spinal. 



Postero-inferior cerebellar. 



The basilar artery is situated at the base of the brain. 

 It runs in the median groove of the pons Varolii, and di- 

 vides into the following branches: 



Transverse. Superior cerebellar. 



Antero-inferior cerebral. Posterior cerebral. 



The internal mammary artery arises and descends within 

 the chest from the under side of the subclavian, alongside 

 of the sternum, upon the cartilages of the ribs, to the 

 sheath of the rectus muscle, where it takes the name of the 

 superior epigastric; the continuation of this vessel joins the 

 epigastric branch of the external iliac. This artery is 

 crossed by the phrenic nerve just as it enters the chest. It 

 distributes to the muscles of the abdominal walls and gives 

 off several branches, which are as follows: 



Comes nervi phrenici. Anterior intercostal. 



Mediastinal. Perforating. 



Pericardiac. Musculophrenic. 



Sternal. Superior epigastric. 



