MUSCLES OF THE ANTERIOR LIMBS. 



339 



8. The square pronator, a thick, quadrilateral muscle with transverse fibres, situated at the 

 deep and inferior portion of the forearm. This muscle in the Dog is much more extensive in 

 length. 



2. External Region. 



The muscles of this region are four in number, two of which, the supinators, are only 

 represented in Carnivorous animals : — 



J. The long supinator forms a prominent mass at the bend of the elbow. It is attached t» 



Fig. 189. 



Fie. 190 



eUPERFIClAL MUSCLES OF HUMAN FOREARM. 



1, Biceps, with its tendon ; 2, brachialis an- 

 ticus ; 3, triceps ; 4, pronator radii teres ; 

 5, flexor carpi radialis ; 6, palmaris lon- 

 gus ; 7, a fasciculus of flexor sublimis 

 digitorum ; 8, flexor cnrpi ulnaris ; 9, 

 palmar fascia; 10, palmaris brevis ; 11, 

 abductor pollicis; 12, flexor brevis pol- 

 licis ; 13, supinator longus; 14, extensor 

 ossis metacarpi, and extensor primi inter- 

 nodii pollicis. 



DEEP LAYER OF SUPERFICIAL MUSCLES OP 

 HUMAX FOREARM. 



1, Internal lateral ligament of elbow-joint ; 

 2, anterior ligament ; 3, orbicular ligament 

 of radius ; 4, flexor profundus digitorum ; 

 5, flexor longus pollicis ; 6, pronator quad- 

 ratus ; 7, adductor pollicis ; 8, dorsal in- 

 terosseous of middle, and palmar inter- 

 osseous of rmg, finger ; 9, dorsal inter- 

 osseous muscle of ring-finger, and palmar 

 interosseous of little finger. 



the inferior third of the external border of the humerus, and to the base of the styloid process 

 of the radius. It is a flexor of the forearm, not a supinator, as its name indicates. 



2. The first external radial is represented by a portion of the anterior extensor of the 

 metacarpus of animals. It commences at the inferior part of the external border of the humerus, 

 and terminates at the posterior part of the base of the second metacarpal. 



3. The seco7id external radial, also represented by a portion of the anterior extensor of the 

 metacarpus, terminates at the base of the third metacarpal. 



4. The shart supinator, a muscle bending round the upper third of the radius, is the 

 essential agent in supination. 



