MUSCLES OF RIGHT SIDE OF TRUNK AND HEAD 89 



51. Obliquus externus (o.e. abdominis) muscle: Lumbo- 

 dorsal fascia, xiphoid process and last ten ribs; to linea alba and 

 inguinal ligament. Constricts abdomen. Method: Insert the 

 grooved director through a small incision, made with a sharp 

 scalpel in the middle of the muscle, between the external and the 

 internal obhque m. (52) and transect craniad, then reverse the 

 grooved director and transect caudad. Reflexing the two ends 

 of the transected muscle will reveal the internal oblique m. (52). 



52. Obliquus internus (o.i. abdominis) m.: Last four ribs, 

 inguinal ligament and lumbar vertebrae; to linea alba, by an 

 aponeurosis which is involved with the rectus abdominis m. 

 (54). Compresses abdomen. Transect, to expose the trans- 

 versalis m. (53). 



53. Transversalis abdominis m.: Last seven ribs and apo- 

 neurosis with internal oblique m. (52) ; to linea alba. Constricts 

 abdomen. Do not cut through this muscle, for to do so will 

 open the abdominal cavity. 



54. Rectus abdominis m.: Pubis; to sternum and costal 

 cartilages II- VII. Compresses abdomen. The rectus is closely 

 associated with the inserting tendonous sheaths (aponeuroses) 

 of the external and internal obhque mm. (51, 52). 



55. Serratus posticus m.: Vertebral spines from the middle 

 cervicals to lumbars; to last eight ribs. Probably elevates the 

 first four to six ribs (inspiration) and depresses the others 

 (expiration) . This muscle is divided into a superior (anterior) 

 and an inferior (posterior) part in man and in the cat, but in the 

 rabbit both parts are fused into one continuous broad sheet of 

 tendon and short muscle belly. The broad aponeurosis from 

 which it arises is fused with the splenius capitis m. (58) on the 

 neck and with the lumbodorsal fascia caudad. Method: Do not 

 injure the tendon of this muscle, but make the transection 

 through its belly close to the ribs, leaving part of the muscle 

 attached to its broad tendon. 



56. External intercostal mm.: Caudal surface of each of 

 first eleven ribs; to the cranial surface of the next rib caudad. 

 Raise the ribs; therefore these are muscles of inspiration. The 



