S6 A MANUAL OF ZOOLOGY 



Muscles of the Eye Ball — The levator bulbl is a thin 

 sheet of muscle ventral to the eye ball. What is its func- 

 tion? The recti muscles consist of four separate muscles 

 with their origin on the inner posterior angle of the eye 

 socket and their Insertion on the eye ball. Locate eachf 

 rectus superior, rectus inferior, rectus externus, and rectus 

 internus. The oblique muscles are two in number with 

 their origin on the palatine bone at the anterior end of 

 the orbit and with their insertion on the eye ball; superior 

 oblique is inserted on the dorsal surface of the eye ball 

 in front of the rectus superior; inferior oblique passes un- 

 der the rectus internus and is Inserted between it and the 

 rectus inferior. The retractor bulbi has its origin on the 

 parasphenoid embracing the optic nerve to the eye ball 

 where it is inserted. Look for it from below after -remov- 

 ing the recti muscles. 



The Muscles of the Fore Limb — The sub-suprascapula 

 has its origin on the ventral surface of the proximal end 

 of the suprascapula and its insertion on the upper anterior 

 surface of the scapula. The subscapula is similar in shape- 

 but much larger than the former. Its origin is on the 

 greater part of the inner posterior surface of the scajiula. 

 Its insertion is on the head and the proximal half of the . 

 postero -inferior surface of the humerus. 



Separate the suprascapula from the scapula and re- 

 flect it; find two broad muscles inserted on the under sur- 

 " face of the suprascapula near, its ventral margin. The 

 anterior one, which is the smaller, is called the levator 

 anguli scapulae. The posterior divisioji is called the 

 retrahens scapulae. This latter corresponds to the serfa- 

 tus magnus in the higher forms. It has its origin on the 

 second transverse process and on the dorsal surface of 

 the third, fourth, and fifth vertebrae. What is the origin 

 of the levator anguli scapulae? Atter the viscera have 

 been removed find an oblong muscle, the trapezius, dorsal 

 to the oesophagus and ventral to the extensor dorsi com- 

 munis. Its origin is on the exoccipital and its insertion 

 is on the proximal half pf the ventral surface of the su- 

 prascapula. Press apart the deltoid muscle and the man- 

 dible and find a cylindrical muscle, the levator clavicula; 

 its insertion Is the middle of the anterior border of the 



