412 SPECIAL ANATOMY. 



maxillaris to the eighth cervical nerve ; its inferior branch tra- 

 verses as intercostal nerve along the first rib. 



a. Rami interni s. profundi continue to pass in the direction of 

 the trunk, along the inferior borders of the ribs as far as the 

 middle line of the chest and abdomen. 



a. The thoracic (r. thoracici interni}, these are the branches 

 of the second to the seventh intercostal nerves, which 

 give small branches to the mm. intercostales and trian- 

 gularis sterni (of the third to the seventh), perforate at 

 the outer border of the sternum the mm. intercostal, and 

 pectoralis major, are again reflected outwards, supplying 

 the mammary gland and skin, and unite as internal cu- 

 taneous nerves of the chest with the external. 



/3. The abdominal branches (r. abdominales interni) ; 

 these are, the branches of the eighth to the twelfth inter- 

 costal nerves, are larger, give branches to the mm. in- 

 tercostaks, pass behind the cartilages of the short ribs, 

 and traverse between mm. obliquus intern, and trans- 

 versus abdom. to and in the sheath of m. rectus, supply- 

 ing the muscles and skin of the anterior abdominal walls. 



b. Rami externi s. lateraks perforate (the twelfth excepted) the 

 m. intercostal, extern, from behind forwards, then pass forth 

 on the lateral walls of the chest and abdomen, and divide im- 

 mediately into an anterior and posterior branch. 



a. The thoracic branches (r. thoracici externi), that is, the 

 second to the seventh branch, passing forth between the 

 digitations of m. serratus antic, major. Their anterior 

 branches are reflected inwards, and ramify in the skin 

 of the thorax. Their posterior branches, backwards 

 upon n. latissimus dorsi, give filaments to it, and ter- 

 minate in the skin of the back. The posterior branch 

 [intercosto-humeral] of the second and third n. intercos- 

 tal, goes to the skin of the upper arm, and forms the 

 posterior cutaneous nerves of the superior third of this 

 region of the upper extremity [Nn. Wrisbergii]. 



/3. The abdominal branches (rami abdominales extern.), 

 that is, the eighth to the twelfth branch, passing out be- 

 tween the digitations of m. obliquus extern. Their an- 

 terior branches are reflected inwards, give a branch to 

 m. obliq. extern., and ramify in the skin of the lower 

 part of the anterior abdominal parietes. Their posterior 

 branches pass backwards to the skin of the lumbar re- 

 gion. 



