494 THE MUSCLES AND FASCIAE 



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fasciculi from the anterior annular ligament and palmar fascia; the fleshy fibres 

 pass inward, to be inserted into the skin on the inner border of the palm of the hand. 

 The Abductor minimi digiti (m. abductor dig it i quint i) is situated on the ulnar 

 border of the palm of the hand. It arises from the pisiform bone and from the 

 tendon of the Flexor carpi ulnaris, and terminates in a flat tendon, which divides 

 into two slips; one is inserted into the ulnar side of the base of the first phalanx 

 of the little finger. The other slip is inserted into the ulnar border of the aponeu- 

 rosis of the Extensor minimi digiti. 



Relations. By its superficial surface, with the inner portion of the palmar fascia and the 

 Palmaris brevis; by its deep surface, with the Opponens minimi digiti; by its outer border, 

 with the Flexor brevis minimi digiti. 



The Flexor brevis minimi digiti (m. flexor digiti quint i brevis) lies on the same 

 plane as the preceding muscle, on its radial side. It arises from the convex aspect 

 of the hook of the unciform bone and anterior surface of the annular ligament, 

 and is inserted into the inner side of the base of the first phalanx of the little finger. 

 It is separated from the Abductor at its origin by the deep branches of the ulnar 

 artery and nerve. This muscle is sometimes wanting; the Abductor is then, 

 usually, of large size. 



Relations. By its superficial surface, with the internal portion of the palmar fascia and 

 the Palmaris brevis; by its deep surface, with the Opponens. The deep branch of the ulnar 

 artery and the corresponding branch of the ulnar nerve pass between the Abductor and Flexor 

 brevis minimi digiti muscles. 



The Opponens minimi digiti (m. opponens digiti quint i) (Fig. 358) is of a 

 triangular form, and placed immediately beneath the preceding muscles. It 

 arises from the convexity of the hook of the unciform bone and the contiguous 

 portion of the anterior annular ligament; its fibres pass downward and inward, 

 to be inserted into the whole length of the metacarpal bone of the little finger, 

 along its ulnar margin. 



Relations. By its superficial surface, with the Flexor brevis and Abductor minimi digiti; 

 by its deep surface, with the Interossei muscles in the fourth metacarpal space, the metacarpal 

 bone, and the Flexor tendons of the little finger. 



Nerves. All the muscles of this group are supplied by the eighth cervical nerve through 

 the ulnar nerve. 



Actions. The Abductor minimi digiti abducts the little finger from the middle line of the 

 hand. It corresponds to a dorsal interosseous muscle. It also assists in flexing the proximal 

 phalanx and extending the second and third phalanges. The Flexor brevis minimi digiti 

 abducts the little finger from the middle line of the hand. It also assists in flexing the proximal 

 phalanx. The Opponens minimi digiti draws forward the fifth metacarpal bone, so as to deepen 

 the hollow of the palm. The Palmaris brevis corrugates the skin on the inner side of the palm 

 of the hand and probably serves to protect the ulnar nerve and artery from damage by the 

 pressure of grasping a hard object. 



13. The Middle Palmar Region. 



Lumbricales. Interossei dorsales. 



Interossei palmares. 



The Lumbricales (mm. lumbricales) (Fig. 369) are four small fleshy fasciculi, 

 accessories to the deep Flexor muscle. They arise from the tendons of the 

 Flexor profundus digitorum; the first and second, from the radial side and palmar 

 surface of the tendons of the index and middle fingers, respectively; the third, 

 from the contiguous sides of the tendons of the middle and ring fingers; and the 



