ULNAR REGION. 



Fig. 88.* 



The Flexor brevis pollicis consists of two portions, between which 

 lies the tendon of the flexor longus pollicis. The external portion 

 arises from the trapezium and an- 

 nular ligament ; the internal portion 

 from the trapezoides and os mag- 

 num. They are both inserted into 

 the base of the first phalanx of the 

 thumb, having a sesamoid bone in 

 each of their tendons to protect the 

 joint. 



Relations. By its superficial sur- 

 face with the external portion of the 

 palmar fascia. By its deep surf ace 

 with the adductor pollicis, tendon 

 of the flexor carpi radialis, and tra- 

 pezio-metacarpal articulation. By 

 its external surface with the flexor 

 ossis metacarpi and metacarpal 

 bone. By its inner surface with the 

 tendons of the long flexor muscles 

 and first lumbricalis. 



The Adductor pollicis is a triangu- 

 lar muscle ; it arises from the whole 

 length of the metacarpal bone of the 



middle finger ; the fibres converge to its insertion into the base of 

 the first phalanx. 



Relations. By its anterior surface with the flexor brevis pollicis, 

 tendons of the deep flexor of the fingers, lumbricales, and deep 

 palmar arch. By its posterior surface with the metacarpal bones of 

 the index and middle fingers, the interossei of the second interosseous 

 space, and the abductor indicis. 



Ulnar Region. 



Palmaris brevis, 

 Abductor minimi digiti, 

 Flexor brevis minimi digiti, 

 Flexor ossis metacarpi (adductor). 



Dissection. Turn aside the ulnar flap of integument in the palm 

 of the hand ; in doing this, a small subcutaneous muscle, the palmaris 



* The muscles of the hand. 1 . The annular ligament. 2, 2. The origin and inser- 

 tion of the abductor pollicis muscle ; the middle portion has been removed. 3. The 

 flexor ossis metacarpi, or opponens pollicis. 4. One portion of the flexor brevis 

 pollicis. 5. The deep portion of the flexor brevis pollicis. 6. The adductor pollicis. 

 7, 7. The lumbricales muscles, arising from the deep flexor tendons, upon which the 

 numbers are placed. The tendons of the flexor sublimis have been removed from the 

 palm of the hand. 8. One of the tendons of the deep flexor, passing between the two 

 terminal slips of the tendon of the flexor sublimis to reach the last phalanx. 9. The 

 tendon of the flexor longus pollicis, passing between the two portions of the flexor 

 brevis to the last phalanx. 10. The abductor minimi digiti. 11. The flexor brevis 

 minimi digiti. The edge of the flexor ossis metacarpi, or adductor minimi digiti, is 

 seen projecting beyond the inner border of the flexor brevis. 12. The prominence of 

 the pisiform bone. 13. The first dorsal interosseous muscle. 



