Muscles of the Ann 



311 



Epicondylns 



latei'alis 



Epicondylus 

 niedialis 



Tuberositas 

 radii 



M. supiuator- 



Origin of the 

 m. flexor pollicis 



longus from the 



epicondylus 

 medialis humeri 



M. flexor digitorum 

 profundus 



356. Muscles of the 



right forearm r :^^- Humerus 



(4*^^ layer), viewed from in front. 



(The mm. flexor digitorum profundus 



and flexor pollicis longus have been 



partialh', all the more superficial 



muscles completely, removed.) 



M. pronator qnadratus (see also 

 Fig. 354). Form: flat, (juadrangular. 

 Position: on the volar surface of the 

 forearm near the wrist, immediately 

 upon the radius, the ulna and the 

 membrana interossea; covered by all 

 the flexor muscles going to the hand. 

 Origin: facies volaris ulnae. Inser- 

 tion: the fibers run jiarallel, radial- 

 ward and downward to the facies volaris 

 radii. Action: it pr(5nates the forearm. 

 Inn-ervation: n. interosseus volaris 

 of the n. medianus. 



M. supiuator (0. T. supinator brevis) 

 (see also Figs. 354, 355, 359 and 360). 

 Form: flat, triangidar. Position: 

 close below the elbow joint on the 

 volar, radial and dorsal surface of the 

 forearm, immediately upon the radius, 

 covered by the mm. brachioradialis, 

 extensores carpi and anconaeus. Ori- 

 gin: epicondylus lateralis humeri, lig. 

 collaterale radiale of the elbow joint 

 and crista m. supinatoris ulnae. In- 

 sertion: the fibers run obliquely 

 downward to the facies dorsalis , late- 

 ralis and volaris of the radius, partially 

 surrounding this bone in a curve. 

 Action: it supinates the forearm. 

 Innervation: ramus profundus n. 

 radialis. 



M. extensor carpi radialis longus 



(0. T. extensor carpi radialis longior) 

 (see Figs. 352355, 357359 and 361). 

 F or m : flat , oblong - spindleshaped. 

 Position: usually superficial on the 

 radial side of the forearm, bounded in 



front by the m. brachioradialis, behind Radius 



by the m. extensor carpi radialis brevis. 

 Origin: septum intermuscidare late- 

 rale , margo lateralis and epicondylus 

 lateralis liimieri. Insertion: the 

 fibers run downward and converge in 

 the middle of the forearm to form a 



long, flat tendon, which extends upon the facies lateralis radii (there partly covered by the 

 mm. abductor pollicis longus and extensor pollicis brevis) imder the lig. carpi dorsale (through 

 its second compartment) to the dorsal surface of the basis oss. metacarpalis II; at the wrist 

 the tendon of the m. extensor pollicis longus crosses over it. Action: it flexes the forearm, 

 extends and abducts the hand. Innervation; ramus profundus n. radialis. 



M. flexor 



pollicis 1 



longus 



it. pronator quadratus 



'^,i 



- Tina 



