928 



A MANUAL OF ANATOMY 



intercostal aponeurosis and the parietal pleura. About the level of 

 the angle of the rib it pierces the posterior intercostal aponeurosis, 

 and passes forwards in the subcostal groove of the upper rib' 

 lying between the intercostal muscles. It continues its forward 

 course in this position, in company with the aortic intercostal artery 

 and intercostal vein, the order of these from above downwards 

 being intercostal vein, aortic intercostal artery, and intercostal 

 nerve. The nerve is concealed by the overlapping lower border of 

 the upper rib. Having reached a point about midway between the 

 vertebral column and the side of the sternum, the nerve gives off 



Fig. 381. — Scheme of an Intercostal Nerve. 



S.C. Spinal Cord 



1. Anterior Root of Spinal Nerve 



2. Posterior Root, with Ganglion 



3. Spinal Nerve 



A.P.i). Anterior Primary Division 

 (Intercostal Nerve) 

 S.G. Sympathetic Ganglion 

 R.C. Rami Communicantes 



L.C. Lateral Cutaneous Nerve 

 A.B. Anterior Branch 

 P.B. Posterior Branch 

 A.C. Anterior Cutaneous Nerve 

 P.P.D. Posterior Primary Division 

 E.B. External Branch 

 I.B. Internal Branch 



a large branch, called the lateral cutaneous nerve. The intercostal 

 nerve itself, now reduced in size, leaves the intermuscular space 

 hitherto occupied by it, and enters the internal intercostal muscle, 

 in the substance of which it continues its forward course. 



Having arrived at the anterior extremity of the osseous rib, the 

 nerve cmreges from the internal intercostal muscle and passes 

 inwards on its deep surface, lying at first upon the parietal pleura, 

 and subsequently upon the triangularis sterni muscle, crossing in. 

 its course the internal mammary vessels. On reaching the side ofj 

 the sternum it passes straight forwards, to become an anteriori 



