178 Anatomy of the Rabbit. 



II. THE ABDOMINAL WALL. 



I. Place the animal in the supine position. Make a median in- 

 cision of the skin of the ventral surface extending from the pubic 

 symphysis to the tip of the mandible, being careful not to cut 

 through more than the skin itself. Make three transverse in- 

 cisions on the left side, the first to and along the medial surface 

 of the arm and extending to the elbow, the second midway between 

 the anterior and posterior limbs, the third to and along the medial 

 surface of the thigh and extending to the knee. Work the flaps 

 loose from the surface, using the handle of the scalpel, until the 

 side of the trunk is well exposed. On the right side of the body 

 it is sufficient to clear the middle line. Identify the structures 

 as follows: 

 On the skin : 



(a) The thick compact connective tissue forming the corium. 



(b) The imbedded hair -follicles. 



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

 the skin is attached. 



(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 aponeurotic line extending from the 

 pubic symphysis to the xiphoid process of the sternum. 



(f) 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 last-named portion appears on the medial surface of the 

 humerus. Insertion: The skin of the dorsolateral surface 

 of the trunk. The fibres are directed upward and backward. 

 The muscle is continuous across the back with its fellow of 

 the opposite side, and 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 epigastric, a 

 branch of the femoral (p. 224). Passing into the ventral portion of the 

 cutaneus maximus muscle, it anastomoses forward with the external 



