258 ANATOMY OF THE RABBIT 



which is inserted into the external base of the ear. The entire 

 sheet of muscle is so closely attached to the skin that it is some- 

 times removed with the latter. If in place, it should be raised from 

 the surface, separated posteriorly from its attachment, and turned 

 forward on the head. 



The dissection is mainly muscular, but the arteries and nerves 

 should be kept intact for later examination. 



Identify the manubrium sterni by feeling. The muscle directed 

 forward from it toward the angle of the mandible is the sterno- 

 mastoideus, one of the muscles of the head. The external jugular 

 vein lies on its lateral side and is joined by the transverse scapular 

 vein from the lateral surface of the shoulder. Identify by feeling the 

 clavicle rudiment and the cleidohumeral ligament attaching it to 

 the humerus. Find the mid-dorsal line of the neck, indicating the 

 position of the neck ligament (ligamentum nuchae). Then proceed 

 to uncover the muscles, beginning with those on the ventral side 

 and working around to the shoulder. 



For the general relations of the muscles of the limbs, see pp. 68-70. 



1. Muscles arising from the axial skeleton and inserted on the 

 scapula and clavicle.^ 



(a) The cleidomastoideus. Origin: Mastoid portion of the 

 skull. Insertion: Middle portion of the clavicle. 



The muscle lying on its medial side and arising from the manubrium 

 sterni is the sternomastoideus, one of the muscles of the head. 



(b) The basioclavicularis (basiohumeralis). Origin: Basioc- 

 cipital bone. Insertion: Lateral third of the clavicle and 

 the cleidohumeral ligament. 



(c) The levator scapulae major. Origin: Cartilage union of 

 basioccipital and basisphenoid (sphenooccipital synchon- 

 drosis). Insertion: Metacromion. 



The superficial cervical artery (p. 325) passes obliquely forward 

 and outward under cover of these muscles, ramifying beneath the 

 superior portion of the trapezius in the fat-mass of the side of the neck. 

 Its ascending cervical branch passes forward on the lateral surface 

 of the external jugular vein. 



^The structures of Group 2 may be dissected first if preferred, the serratus 

 anterior muscle being exposed from the lateral surface and divided together with 

 the latissimus dorsi. 



