ANATOMY IN A NUTSHELL. 447 



lion of sympathetic, (4) Longus colli. 



Outer Bide. — (1) Pleura, (2) Left lung. 



Inner Side. — (1) Trachea. (2) (Esophagus, (3) Thoracic duct. 



LESSON CXXXVIII. 

 The Relations of Second Portion of Subclavian Artery are the same 



on each side. 



In Front. — (1) Skin, (2) Superficial fascia, (3) Platysma and deep cer- 

 vical fascia, (4) Sterno-mastoid, (5) Phrenic nerve, (6) Scalenus auticus. 

 ' 7) Subclavian vein. 



Behind. — (1) Pleura, (2) Scalenus medius. 



Aboa t e. — Brachial plexus. 



Below. — Pleura. 



The Relations of Third Portion of Subclavian Artery are the same 

 on each side. 



In Front. — (1) Skin, (2) Superficial fascia, (3) Platysma and deep cer- 

 vical fascia, (4) Descending branches of cervical plexus, (5) Nerve to sub- 

 clavius muscle, (6) Subclavius muscle, (7) Suprascapular artery, (8) Supra- 

 scapular vein, (9) The external jugular vein, (10) Transverse cervical vein. 

 (11) Clavicle. 



Behind. — (1) Scalenus medius, (2) Lower cord of brachial plexus. 



Above. — (1) Brachial plexus, (2) Omo-hyoid muscle. 



Below. — First rib. 



LESSON CXXXIX. 



The branches of the subclavian artery are (1) vertebral, which arises at 

 the upper and back part of the artery and passes upward through the foramina 

 in the transverse processes of the upper six cervical vertebrae. After it passes 

 through the foramen in the transverse process of the atlas, it passes behind the 

 articular process of this bone in the sinus atlantis lying superficial to the sub- 

 occipital nerve. 11 now pierces the dura mater and passes through the torn men 

 magnum of the occipital bone to the front of the medulla oblongata. 



It unites with the opposite vertebral at the low< r border of the pons to form 

 the basilar artery. The branches of the vertebral artery are: (A) the cer- 

 vical branches which send muscular branches to the neck, lateral spinal 

 which pass through the intervertebral foramen and then divides into two 

 branches one of which runs along the nerve roots to the cord and its coverings, 

 the other divides into ascending and descending branches which form with 

 similar branches from above and below loops on the posterior surfaces of the 

 bodies of the vertebrae. (B) cranial branches which send posterior menin- 

 geal branches to the posterior fossa, anterior spina! descends in front of the 

 medulla and unites with its fellow to form a single trunk at the foramen mag- 

 num. This main branch descends in the anterior median fissure of the cord. 

 For description of anterior spinal and posterior spina! see page 337. The pos- 

 terior inferior cerebellar is tin- last branch of this crania] portion and winds 

 around the medulla across the restiform body to the under surface of the cere- 

 bellum. 



