THE RABBIT. 351 



430. The interossei {io), seen, by reflecting the flexor profundus with 

 the lumbricales and the flexor minimi digiti, as three pairs of small 

 muscles lying on the ventral faces of the second to the fourth metacarpals 

 and one on the pre-axial side of the fifth metacarpal : they arise from 

 the metacarpals. The two muscles of each pair are in close con- 

 tact with one another for the gi-eater part of their extent, but 

 separate distally to be inserted into the sesamoid bones at the meta- 

 carpo-phalangeal articulation ; a small additional slip occurs on the 

 post-axial side of the second digit, and one on each side of the fourth : 

 these are much smaller than, and arise ventrally to, the paired muscles. 



LIII. Dissect away the origins and insertions of any 

 muscles still left attached to the shoulder-joint, 

 and make out : 



431. The capsular ligament surrounding the shoulder- 

 joint : it consists of thin fibrous tissue, and is attached on 

 the one hand round the margin of the glenoid cavity 

 and on the other round the neck of the humerus : if 

 it has not already been cut, make an incision through it, and 

 notice that it helps to bound a closed synovial cavity, 

 between the two bones, lined by a delicate synovial 

 membrane which secretes a small quantity of synovial 

 fluid. 



432. A similar synovial cavity at the elbow-joint: the 

 joint is further strengthened by strong lateral ligaments, 

 which pass, one on the pre-axial side from the humerus to 

 the radius, the other on the post-axial side from the humerus 

 to the ulna. 



LIV. Make out the muscles of the hind limb, begin- 

 ning with those which connect it with the trunk : 



On the ventral surface of the vertebral column. 



433. The psoas magnus (Fig. 6,7, B, ps.m), a large 

 muscle in the lumbar region passing longitudinally back- 

 wards from the diaphragin to the thigh : it arises from the 

 last three ribs, the last three thoracic and all the lumbar 



