THE FROG 81 



from the ilium and inserted into the head of the femur, which it rotates 

 inwards. 



(e) Muscles inserted into the hip girdle. 



e. g. Coccygeo-iliacus, arising from the urostyle and inserted 

 into the ilium, which it holds firm as a fulcrum for the movements of the 

 hind-limb. 



(f) Muscles of the Backbone. 



e. g. Longissimus dorsi, a band running the whole length of 

 the back, divided by tendinous intersections, which are attached to the 

 transverse processes, and inserted in front into the skull. It straightens 

 the back. 



Innervation : Twig from I spinal nerve. 



B. MUSCLES OF THE HEAD 



1. Muscles underneath the Head. 



e. g. Sternohyoid, from hyoid to pectoral girdle. 



Geniohyoid, from hyoid to chin. 



Hyoglossus, from hyoid to tongue. 



Petrohyoid, from hyoid to auditory capsule. 



Mylohyoid, submandibular, or submaxillaris ( ), 



a sheet of muscle running from side to side of the lower jaw. These 

 muscles alter the position of the floor of the mouth. 



Innervation : Twigs from I spinal nerve. 



2. Muscles of the Lower Jaw. 



e. g. Temporalis and masseter ( ), arising 



from the skull and inserted into the lower jaw, which they raise. 

 Innervation : Mandibular branch of the V cranial nerve. 



3. Muscles of the Eyeball (Fig. 466). 



Rectus superior, r. inferior, r. externus, r. internus, arising from 

 the skull in the hinder part of the orbit and inserted into the eyeball. 



Innervation: All but the rectus externus from the III cranial 

 nerve. The r. externus by the VI cranial nerve. 



Obliquus superior and o. inferior, arising from the skull in the 

 front part of the orbit and inserted into the eyeball. 



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

 inferior by the III cranial nerve. ,-,,. 



C. MUSCLES OF THE FORE-LIMB 



1. Muscles for the Upper Arm. 



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

 humerus. It raises the arm. 



2. Muscles for 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. 



