82 General Biology 



Innervation : Obliquus superior by the IV cranial nerve and o. 

 inferior by the III cranial nerve. 



C. MUSCLES OF THE FORE-LIMB 



1. Muscles of the Upper Arm. 



e. g. Deltoideus, arising from the scapula and inserted into the 

 humerus. It raises the arm. 



2. Muscles of the Fore-Arm. 



Triceps brachii or anconaeus ( ), arising 



from the scapula and humerus, and inserted into the upper end of the 

 ulna. It straightens the arm. 



There is no Biceps muscle in the arm of the frog. 



3. The muscles of the Wrist and Fingers are numerous and com- 

 plicated. 



Innervation : Branches and twigs of II spinal or brachial 

 nerves innervate all arm and finger muscles. 



D. MUSCLES OF THE HIND-LIMB 



(1) Superficial muscles of the Thigh on the Preaxial (apparent 

 ventral 1 Surface. 



1. Sartorius ( ), a long, narrow band arising 

 from the lower end of the ilium, lying obliquely upon the abductor 

 magnus, and inserted into the tibia on its inner side near the end. It 

 bends the knee. 



2. Adductor magnus, a large muscle arising from the pubis and 

 ischium, lying along the inner border of the sartorius and inserted 

 into the femur near its lower end. It draws the thigh toward the body. 



3. Adductor longus, a long, narrow muscle lying along the outer 

 side of the adductor magnus, and often completely hidden by the 

 sartorius ; it arises from the iliac symphysis beneath the sartorius, and 

 unites a little way beyond the middle of the thigh with the adductor 

 magnus. It adducts the thigh and draws it ventrally. 



4. Gracilis major ( ), or rectus interims major, 

 is a large muscle arising from the ischium, lying along the inner side of 

 the adductor magnus, and inserted into the inner-side of the head of the 

 tibia. It bends the knee. 



5. Gracilis minor, or rectus internus minor, is a narrow flat band of 

 muscle running along the inner, or flexor margin of the thigh. It rises 

 from a tendinous expansion connected with the ischial symphysis, and 



^he femur of the frog rotates away from the midline more than does the femur of man. 

 Consequently the true outer border of the frog's thigh is equivalent to the inner border of man's. 

 In other words the preaxial surface of the frog's thigh is equivalent to the inner surface of man's. 



