FASCIA AND MUSCLES OF THORACIC REGION 195 



Small foramina are in the crura for the splanchnics on both 

 sides, for the small azygos vein on the left side; the sympathetic 

 cord perforates the crus or passes under the internal arched 

 ligament. 



There are four weak places: (1) Between the costal and 

 vertebral portions near the quadratus lumborum; (2) between 

 the costal and sternal portions = Larrey's spaces; (3) the 

 esophageal opening; (4) where the sympathetic cords pierce 

 the crura. Left side, as a whole, is the weaker; at Larrey's 

 space is peritoneum below, then areolar tissue, then pericardium 

 on the left side and pleura on the right side. 



Highest point of the diaphragm on the right side in the 

 dead body is the level of the fifth rib cartilage with the sternum; 

 on the left side, of the sixth cartilage with the sternum (Quain) ; 

 the midportion is flat, supports the heart, and is nearly immov- 

 able. A considerable extent of the origin of the diaphragm 

 is in contact with the thoracic wall. 



Relations are, above, pleurae and pericardium, lungs, and 

 heart; below, peritoneum, liver, stomach, pancreas, spleen, 

 and kidneys. 



Nerves. Phrenics, lower intercostals, and sympathetic. 



Actions. By its contraction and descent the viscera are 

 pushed down and thorax lengthened; it elevates the ribs when 

 its vault is supported by the abdominal viscera; its anterior 

 fibers oppose forward movement of the sternum. 



THE FASCLffi AND MUSCLES OF THE THORACIC REGION 



Fascia of Pectoral Region. Superficial contains the mammary 

 gland, sending septa into it and supporting it. These were 

 called by Sir Astley Cooper the suspensory ligaments. The 

 deep fascia is thin, covering the surface of the pectoralis major 

 muscle; it is attached to the middle of the front of the sternum, 

 above to the clavicle, and below is continuous with the fascia 

 over the shoulder, axilla, and thorax. It encloses the space 

 between the pectoralis major and latissimus dorsi muscles; 

 it is called in this region the axillary fascia. This latter fascia 

 sends a prolongation upward under cover of the pectoralis 

 major muscle, called the deep pectoral fascia. 



The costocoracoid membrane or clavipectoral fascia lies beneath 



