THE MUSCLES. 169 



332. 11. Interossei dor sales s. bicipites, 4. 



Pos. : in the spaces between Oss. metacarpi I. to F., to be seen 

 from the back and palm of the hand. Or. : sides of Ossa meta- 

 carpi II. to F., with two heads, which Art. perforans separates. 

 Ins. : 1. on the radial side of Phalanx I. of index finger; 2. the 

 same on the middle finger ; 3. on the Ulnar side of the middle 

 finger; 4. the same on the ring finger. Use: draws the Index 

 from the Middle finger, the Middle finger from the Ring and In- 

 dex, the Ring finger from the Middle ; they spread out the second 

 and the fourth from the middle finger. 



Nerves : ulnaris r. profund. volar. 



333. 1. Aponeurosis palmaris, close beneath the skin of the 

 hollow of the hand, it forms a sheath for all its muscles. The 

 central portion is triangular and strong, arises from the anterior 

 surface and the inferior border of Lig. carpi volare and the ten- 

 don of palmaris longus (between the two points Art. ulnaris 

 enters into the palm of the hand) ; it divides in the region of the 

 Capitul. oss. metacarpi into eight parts for the second to the fifth 

 fingers, and is strengthened by transverse fibres. By this four 

 arches arise for the tendons of Mm. flexor es, and three between 

 them for Vasa and Nn. collaterales of the fingers and Mm. lum- 

 bricales. Loose uniting tissue separates the middle part from the 

 subjacent structures: Arms arterios. superficial, volse ; Nn. 

 median, and ulnaris tendin. mm. flexor. Externally, as a con- 

 tinuation of the tendon of abductor pollicis longus, the external 

 portion of the Aponeur. palm, envelopes the muscles of the ball 

 of the thumb ; internally, as a process of the tendon of flexor 

 carpi ulnaris, the inner portion, the muscles of the ball of the 

 little finger ; here the m. palmaris brevis is connected. It loses 

 itself on the first phalanx in the sheaths of flexor digit, and ligg. 

 capit. os. metacarpi. 



334. 2. F. dorsalis manus. ; a. the superficial is a thin layer, 

 covering the tendons of extens. digitor. comm., and attached to 

 the second and fifth metacarpal bones ; b. the deep, covers the 

 interrossei, and attaches itself to all the metacarpal bones, con- 

 sisting of loose elastic uniting tissue, which serves instead of 

 synovial capsules. 



335. 3. Pulleys (trochless) of the flex, digitor. comm. ; con- 

 sist of fibro-cartilaginous portions with transverse fibres, lying 

 transversely before all three phalangeal articulations of the second 

 to the fifth fingers. On the first joint they form a connected flat 

 surface (one inch long), to which the aponeurosis palmar, is at- 

 tached. 



