The Abdominal Wall. 179 



thoracic artery, a branch of the lateral thoracic. The corresponding veins 

 are usually conspicuous in the female, since the vessels supply the mam- 

 mary glands. A second anastomosis in the cutaneus muscle is formed 

 laterally by a branch of the subscapular artery which passes backward 

 from the axillary border of the scapula, uniting with an anterior branch 

 of the iliolumbar artery. 



The inguinal lymph nodes ilymphoglandulae inguinales) are small, 

 oval, brownish bodies lying in the inguinal furrow. 



2. Remove the cutaneus maximus from the surface. Identify 

 the following points of attachment of the abdominal muscles proper: 



(a) The linea alba. 



(b) The linea semilunaris, a slightly curved line situated 

 laterally a short distance from the linea alba. 



(c) The ribs and the costal arch. 



(d) The lumbodorsal fascia (fascia lumbodorsalis), a broad, 

 white sheet of connective tissue extending over the posterior 

 thoracic and lumbar regions. 



(e) The inguinal ligament (ligamentum inguinale), a stout 

 white cord, stretched between the s ymphysis publ ic anHthp 

 jh ac cre st. 



3. Identify on the surface the external oblique muscle (m. 

 obliquus externus abdominis). Origin: The posterior ten ribs by 

 separate slips, the xiphoid process, and the lumbodorsal fascia. 

 Insertion: The linea alba and the inguinal ligament. The fibres 

 are directf i from an anterior dorsal position downward and back- 

 ward, the more dorsal ones almost directly backward. Some of the 

 anterior slips of origin interdigitate with those of the thoracic 

 portion of the serratus anterior muscle. Some are concealed by the 

 pectoral muscles. 



The muscle crossing the breast from the sternum to the arm is the pectoralis 

 major. That passing forward from the lumbodorsal fascia to the medial surface of 

 the humerus is the latissimus dorsi. The margins of these muscles may be raised 

 where they conceal the external oblique. 



4. Taking a line between the iliac crest and the xiphoid process, 

 divide the muscle, and then separate it fully from the next, which 

 may be distinguished by the cross direction of its fibres. Note the 

 separate slips of origin and the difference in appearance between 

 the fleshy portions of the muscle and its ventral tendinous expansion 

 or aponeurosis; then remove it from the surface. 



