THE ABDOMINAL WALL 221 



(b) the hair-follicles imbedded in it, appearing as dots. 



(c) The loose subcutaneous tissue (tela subcutanea) by which 

 the skin is attached. In some animals, large amounts of fat 

 are at times deposited in this layer. Some fat may be 

 present in the rabbit but the quantity is not usually great. 



(d) In the female: the mammary glands (mammae), forming 

 a layer on the inner surface, and more or less closely aggre- 

 gated about the mammary nipples. 



On the exposed surface: 



(e) The linea alba, a white tendinous line extending from 

 the pubic symphysis to the xiphoid process of the sternum. 



(/) The cutaneus maximus muscle, a thin sheet of muscle 

 fibres covering the entire lateral surface of the thorax and 

 abdomen. Origin : the linea alba, the ventral surface of the 

 sternum in its posterior portion, and the deltoid tuberosity. 

 The portion originating on the last-named appears on the 

 medial surface of the humerus. Insertion: the skin of the 

 trunk, mainly dorsolaterally but some fibres reaching the 

 mid-dorsal line so that the muscles of the two sides are 

 continuous across the back. The fibres are directed 

 upward (in the natural position of the animal) and back- 

 ward. The muscle is extended backward to the dorsum 

 of the tail. It is used in shaking the skin. 



The artery passing forward for a short distance in the inguinal 

 region and lying in the subcutaneous tissue is the superficial epi- 

 gastric, a branch of the femoral (p. 279). Passing into the ventral 

 portion of the cutaneus maximus muscle, it anastomoses forward with 

 the external thoracic artery, a branch of the lateral thoracic. The 

 corresponding veins are usually conspicuous in the female, since the 

 vessels supply the mammary 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 (lymphoglandulae inguinales) are 

 small, oval, brownish bodies lying in the inguinal furrow. 



2. Separate the cutaneus maximus from the surface of the muscle 



