222 ANATOMY OF THE RABBIT 



beneath. Identify the following points of attachment of the 

 abdominal muscles proper: 



(a) The linea alba. 



{b) The xiphoid process of the sternum, the ribs, and the 

 costal arch. 



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

 white sheet of connective tissue extending over the back in 

 the posterior thoracic and lumbar regions. 



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

 white cord, stretched between the symphysis pubis and the 

 iliac crest. 



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

 externus abdominis). Origin: the xiphoid process, the posterior 

 ten ribs by separate slips, and the lumbodorsal fascia. Insertion : 

 the linea alba and the inguinal ligament. The fleshy portion, 

 or muscle proper, covers the abdomen lateral to the tendinous 

 portion, or aponeurosis, which appears as a longitudinal, 

 whitish band attaching the muscle to its insertion. The fleshy 

 portion and the aponeurosis meet along a slightly curved line 

 a short distance lateral to the linea alba. The fibres are directed 

 from an anterior dorsal origin downward and backward, the 

 more dorsal ones almost directly backward, and the fibres of the 

 aponeurosis continue the line of the muscular fibres attached 

 to them. 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 external oblique muscle, and then separate it fully 

 from the next, which may be distinguished by the markedly 

 different 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. This separation cannot 



