THE MUSCLES. 163 



. Second layer. 



304 5. Flexor digitorum communis sublimis (s. perforatus). 



Pos. : beneath the four muscles last described. Covers the 

 following muscle and nerv. medianus ; passes under Lig. carpi 

 volar. propr. The four tendons are perforated in the region of 

 the first phalanx by those of the following muscle. Or. : 1 . 

 Condyl. intern, hum. 2. Inner side of Proc. coronoid. Ulnse. 

 3. interior border of Radius. Ins. : Lateral surfaces of Pha- 

 lanx II. of the second to the fifth finger. Use : to flex the 

 second phalanx of the second to the fifth finger. 



y. Third layer. 



305. 6. Flexor digitorum communis prof undus (s.perforans). 

 Pos.: beneath the before mentioned muscles, covering the 



Ulna, in the palm of the hand, the Mm. interossei and adductor 

 pollicis. Or.: 1. Jlngulus intern. Ulnse (above and internally). 

 2. Lig. interosseum (two-thirds). Ins. : Basis Phalang. III. 

 of the second to the fifth finger. Use : to flex the ungual pha- 

 lanx of the second to the fifth finger. 

 Nerves : (5) median^ (6) median, [et ulnaris']. 



306. 7. Flexor Pollicis longus. 



Pos. : external and close to the last muscle ; covers the radius 

 and lig. inteross. Or. : 1. Mar go intern. Radii (three-fourths). 

 2. Lig. interosseum. Ins. : Basis Phalang. II. of the thumb. 

 Use : to flex the ungual phalanx of thumb. 



Nerves : interosseous intermix. 



8. Fourth layer. 



307. 8. Pronator quadratus. 



Pos. : at the inferior extremity of the anterior surface of the 

 forearm, close upon the bones, beneath Artt. radialis and ulnaris. 

 Or. : Jlngul. intern. Ulnse (the lower fourth). Ins. : angul. 

 anticus et Marg. intern. Radii. Use : rotates the inferior ex- 

 tremity of the radius upon the ulna, thus pronates the hand. 



Nerves : interosseous internus. 



b. Muscles upon the outer surface of the fore-arm. 



308. 9. Supinator longus s. brachio-radialis. 



Pos. : between the volar and dorsal surface of the arm ; in the 

 upper arm, internal and close to it, brachial. intern., separated 

 by nerv. radial., then upon it ; covered by the skin, upon pronat. 

 teres,flex. pollic. long., along the inner border, upon the fore- 



